Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: purpletele on March 06, 2020, 09:36:18 pm
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I have reviewed the Trem-O-Nator Schematic and the Hoffman AB763 Schematic and Layout.
I enlarged the Layout and performed some Old School Editing to White Out the deleted components and draw in new values or components.
I think I have followed the schematic changes and layout changes as shown on the Trem-O-Lator Detail for the BandMaster, but I could sure use some critique of my artwork for accuracy.
Also, I am not understanding where the Insertion point will be for the Intensity Pot. On my art work I left the right lug of the Intensity Pot Unconnected, not quite sure of how to close this circuit.
As always, I really appreciate the help, my amps continue to improve with all the help and that is very special and important to me
Thanks you
Brian V
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early eyes,
the bias pot wiper/cap wire to the middle of the 220k's through the INT is eliminated on the layout.
the schematic has it still on the INT pot. you wanna get that wire correct, regardless of trem type
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This should work...
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early eyes,
the bias pot wiper/cap wire to the middle of the 220k's through the INT is eliminated on the layout.
the schematic has it still on the INT pot. you wanna get that wire correct, regardless of trem type
Thank you
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This should work...
That is Gorgeous!!
Thank you
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Just a note on the footswitch... If you use an RCA jack you will have to connect the footswitch for the tremolo to work.
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Just a note on the footswitch... If you use an RCA jack you will have to connect the footswitch for the tremolo to work.
Oh thank you. If I just disconnect the footswitch will that close the circuit and have the Tremolo work?
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Now what did I just say? :BangHead:
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Now what did I just say? :BangHead:
Sorry, typing without digesting what I read. Foggy head, no amp work for me today
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Just pickin' at you. I had assumed that you used a RCA phono jack like on Hoffman's layout. I used a 1/4" Switchcraft switching jack on mine just so I don't have to plug in a footswitch.
You about done with the mod? Let us know what you think.
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Just pickin' at you. I had assumed that you used a RCA phono jack like on Hoffman's layout. I used a 1/4" Switchcraft switching jack on mine just so I don't have to plug in a footswitch.
You about done with the mod? Let us know what you think.
I'll be getting the parts Tuesday or Wednesday, and I'm excited about making the change. I used the RCA phono jack, but I don't ever use the footswitch, I like the idea of the Switchcraft jack.
Blossoms, rain and wind is intoxicating to me so today is a good day to just play guitar.
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Foggy head, no amp work for me today
:laugh:
I call it crayon time, usually after 6:20 pm :icon_biggrin:
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Trem-O-Nator Update
All systems are working! The tremolo seems much better than before, I will have a chance to AB it with my other Deluxe.
The drawing was fantastic, thank you for that!!
I used the 50K RA Intensity Pot and I added the .022 cap nearest V4 in lieu of the .01. The Mod schematic had .022, let me know if that is incorrect.
The Tremolo is very smooth and sounds lush, I am getting spoiled but I feel like there could be a bit more Intensity. Is that possible to tweak any components for more intensity?
I am going to try the change of the RCA jack to a Switchcraft switching jack.
I'm going to gear up for the Princeton later this week, that Trem could use a boost.
Thank you very much, successful mod!
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Super nice looking build! :thumbsup:
How is the floor noise at idle? Quiet amp?
With respect, Tubenit
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I feel like there could be a bit more Intensity. Is that possible to tweak any components for more intensity?
Replace the 10K cathode resistor with a 47K. Also try with no cathode resistor. Any better?
Edit... I wonder if the Xvive opto is just not quite the same as the Vactec Vactrol VTL5C1? Could be a factor with the intensity. My Vactec has way more intensity than I could ever use.
While you are experimenting I'd like for you to try a Vactec to see if there is a difference with intensity. You can get some from AES...
https://www.tubesandmore.com/products/optocoupler-vactec-vtl5c1-vactrol-new-old-stock
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Super nice looking build! :thumbsup:
How is the floor noise at idle? Quiet amp?
With respect, Tubenit
Thank you Jeff, this amp is fairly quiet, my other Deluxe is really quiet. Haven't determined the difference. Both have cool chassis' made by a guy on Reverb. The combo chassis is really light!
It's a souped up AB763, 6l6's with a 40 Watt OT
BV
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I feel like there could be a bit more Intensity. Is that possible to tweak any components for more intensity?
Replace the 10K cathode resistor with a 47K. Also try with no cathode resistor. Any better?
Edit... I wonder if the Xvive opto is just not quite the same as the Vactec Vactrol VTL5C1? Could be a factor with the intensity. My Vactec has way more intensity than I could ever use.
While you are experimenting I'd like for you to try a Vactec to see if there is a difference with intensity. You can get some from AES...
https://www.tubesandmore.com/products/optocoupler-vactec-vtl5c1-vactrol-new-old-stock
I installed the 47 K resistor without noticeable results.
I thought the same thing about the Chinese Part, but I wanted to root out any mistakes that I might have made.
I will make a video in the next day or so but it really sounds exceptionally nice, but it's not a dizzy warble.
I'll order up a few from AE and test it again in a few days.
I just played it again and it is really cool, that was after a few beers. I'm kind of hoping the Chinese LED's are not as powerful, I'd like to get a little more juice in the soup just to know it's there.
These amps that I have at home are getting really nice, thank you!
Brian Vallis
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I installed the 47 K resistor without noticeable results.
Now try it with NO resistor.
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I installed the 47 K resistor without noticeable results.
Now try it with NO resistor.
Just saw this, I'll give a try shortly
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I installed the 47 K resistor without noticeable results.
Now try it with NO resistor.
I lifted the 47K resistor an I couldn't discern any difference.
Update, the intensity feels a little more pronounced
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Hi, purpletele, really nice build and great implementation of the tremolo. Could you provide some more info about your chassis? It looks to be the missing link between the Princeton Reverb and two-channel Deluxe. How wide is it? I did a little searching on Reverb but did not see one like it. Thanks
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Hi, purpletele, really nice build and great implementation of the tremolo. Could you provide some more info about your chassis? It looks to be the missing link between the Princeton Reverb and two-channel Deluxe. How wide is it? I did a little searching on Reverb but did not see one like it. Thanks
Hi,
The chassis is essentially a copy of the Princeton Reverb chassis such as the Mojotone.
I found Steven O'Conner of Synaptic Amplification on Reverb. I asked him to reproduce the Princeton chassis but I gave him a dimension to cut in an IEC. I had to give him the dimension's for the record, and he will need to know the face angle. It seems I was about 70 degrees, I was matching the angle on the cabinet.
I used a Princeton Tall Boy Cabinet from Mather Amp Cabinets. I had to cut a leg off of the back panel to expose the IEC.
I used the strap bolts that go through the chassis.
When I have Synaptic's build me a chassis for a Champ I have Synaptics deliver the chassis to Mather and I have him mount the chassis, that is when I have bought a new cab.
The chassis is really light and easy to drill.
Let me know if you need other photos or info
BTW the last photo is a Princeton in a Champ, it's cool!
Brian V
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thanks much! Nice looking amplifiers.
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Trem-O-Nator Update
The American NOS parts from Antique Electronic changed the game! :occasion14:
Great suggestion
Much more pronounced, I took some quick video with a mic, that will come later.
I filmed a couple of chords with the Chineese component installed and then made the change and video taped that.
After that I re-installed the 47K resistor that I had previously pulled out. Couldn't tell if it made a difference, I will have to listen to the sound on the video.
Always fun when a component makes such a difference.
BV
Modified Update: I'm getting a static/Microphonic sound on the V3-7 Wire going up to the the 470K resistor that ties to the middle lug of the Reverb. I changed the tube but that didn't change the static.
Any thoughts on how that became affected?
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Trem-O-Nator Update
The Trem-O-Nator is working better than anticipated, but the changes caused some imbalance on the Reverb circuit.
I V3-7 is a hot wire and the voltage at that pin is 283, and I should see +-200V based upon my previous records.
On the T-o-N circuit I have replaced the 47K resistor with the 10K as designed.
Any thoughts on trouble shooting the voltage increase at V3?
Thanks,
BV
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I V3-7 is a hot wire and the voltage at that pin is 283, and I should see +-200V based upon my previous records.
I hope not! V3-7 should be zero volts. According to your voltage chart you have 283V on V3-6. Probably what you meant?
I notice that V3-1 has also increased. I bet that power supply nodes B, C, and D are all higher too. What say you? The ton mod removed one triode that was fed from B+ node B. I would expect all the downstream voltages to increase. Don't know how much.
283V is quite normal for the bigger 6L6 AB763s. Other than the increased voltage, is the amp misbehaving?
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I V3-7 is a hot wire and the voltage at that pin is 283, and I should see +-200V based upon my previous records.
I hope not! V3-7 should be zero volts. According to your voltage chart you have 283V on V3-6. Probably what you meant?
I notice that V3-1 has also increased. I bet that power supply nodes B, C, and D are all higher too. What say you? The ton mod removed one triode that was fed from B+ node B. I would expect all the downstream voltages to increase. Don't know how much.
283V is quite normal for the bigger 6L6 AB763s. Other than the increased voltage, is the amp misbehaving?
The amp is misbehaving! I get a very distorted notes on the Lower register Strings, But the Trem sounds swirly!
Voltages at the Nodes:
A = 450 V
B = 444 V
C = 442 V
D = 429 V
Note regarding 6L6 tubes: I believe the original voltages taken in 2018 had 6v6 tubes installed.
V3-6 is the Hot wire and not V3-7
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Steve,
Any thoughts on modifying components in the Reverb Circuit to accommodate the added voltage from the T-O-M?
I seem to have some time on my hands, and I would love to help make this amp great again.
BV
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Replace R68 and R69 with 10K 3W resistors. These are the values for a DR.
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Replace R68 and R69 with 10K 3W resistors. These are the values for a DR.
Thanks, this is the fun part.
It will be tomorrow for the work I have Boglevirus right now.
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Replace R68 and R69 with 10K 3W resistors. These are the values for a DR.
I replaced R68 & R69 with 10K 3W resistors with limited improvement. I'll check to see if I have 20K 3W resistors and see if that knocks it down.
Thanks
BV
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I'll check to see if I have 20K 3W resistors and see if that knocks it down.
Don't bother. This is just going deeper into a rabbit hole.
Let's rewind a bit. so, you have "very distorted notes on the Lower register Strings". Did this just pop up since the tremolo mod? Do you suspect the tremolo mod caused this behavior? If so, pull the trem tube and disconnect the wire on the wiper of the INT pot. This totally removes the trem circuit. Still distorted?
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I'll check to see if I have 20K 3W resistors and see if that knocks it down.
Don't bother. This is just going deeper into a rabbit hole.
Let's rewind a bit. so, you have "very distorted notes on the Lower register Strings". Did this just pop up since the tremolo mod?
The amp was performing well without any distortion on the lower register strings prior to the Trem Mod. I can't imagine not noticing such nasty distortion
Do you suspect the tremolo mod caused this behavior? If so, pull the trem tube and disconnect the wire on the wiper of the INT pot. This totally removes the trem circuit. Still distorted? I pulled the wire on the middle lug of the Intensity Pot but I still have light distortion on the D String.
I still have the changed 10K resistors on the B+ Rail
I replaced the 10K resistors with the original 1K and 4.7K. With the Intensity wiper disconnected and the V4 tube pulled out I had a nasty reverb scream.
I am leaving it with the original B+ resistors in place.
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Symptoms keep changing. I suspect we are dealing with collateral damage that is not related to the trem mod. I notice that your reverb pot wires are routed directly under the VTL and parallel to the wire from the INT pot. Unsolder both white wires from the reverb pot and reroute them directly/diagonally from the board to the pot. If this helps the reverb scream I suggest using shielded wire for both of these wires, shield connected to the pot buss.
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Symptoms keep changing. I suspect we are dealing with collateral damage that is not related to the trem mod. I notice that your reverb pot wires are routed directly under the VTL and parallel to the wire from the INT pot. Unsolder both white wires from the reverb pot and reroute them directly/diagonally from the board to the pot. If this helps the reverb scream I suggest using shielded wire for both of these wires, shield connected to the pot buss.
I moved the reverb wires into a Flying Posture and that quieted the Demon. I'll replace those with Shielded wires.
I have the original resistors in the B+ Rail. The amp is more quiet than before. I have the Trem circuit disconnected and I still have the distortion on the E, A & D strings
V3-6 and V3-7 remain microphonic
That is a little forward progress
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Looks like I'll have a little more time, we just shut down a 28 Million dollar construction project.
Steve,
Do you think we should move forward with trying to resolve the distortion issue? Or do you think I should revert to the original design?
If you have ideas, I have the time. It would be cool to work through the Princeton down the road.
Brian V
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Do you think we should move forward with trying to resolve the distortion issue? Or do you think I should revert to the original design?
Let's try to fix it. First, answer these...
Are you using a 50K intensity pot? Is the INT pot ground lug securely attached to the preamp ground buss? Now try this...
Replace the 47K resistor that was removed from the board when you started this mod. Disconnect both INT pot wires at the board. Pull the Tremolo tube. This totally isolates the entire trem circuit from your amp. The amp is now a basic single channel AB763 with reverb but no tremolo. At this point, do you still have distortion? If so, then something has changed while you were doing the mod but it is unrelated to the mod. It's collateral damage. If this is the case, leave the amp wired like this until we solve the distortion issue.
See attached...
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Yes, put back that 47k resistor. I did the Trem-O-Nator mod last week on Doug`s AB763 6V6 amp I built for a friend back in 2005. I took the 47k out when doing the mod because the original Fender schematic did not have it. The amp had too much gain and sounded over driven so I put it back in and the amp cleaned up nicely. My $.02 Punky
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Yes, put back that 47k resistor. I did the Trem-O-Nator mod last week on Doug`s AB763 6V6 amp I built for a friend back in 2005. I took the 47k out when doing the mod because the original Fender schematic did not have it. The amp had too much gain and sounded over driven so I put it back in and the amp cleaned up nicely. My $.02 Punky
Did you use a 50k int pot? The whole purpose of that 47k is to simulate the missing 50k int pot in the Hoffman ab763.
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Doug`s power tube bias vary trem had a 250k pot which I tried first because it was in there. The trem on the Trem-o-Nator was a bit week, so I put a 50kC pot in and the trem was stronger. Cant remember if I did the 47k removal test with the 250k pot or not. I must have. Thanks for clearing that up.
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Do you think we should move forward with trying to resolve the distortion issue? Or do you think I should revert to the original design?
Let's try to fix it. First, answer these...
Are you using a 50K intensity pot? yes, 50K ra
Is the INT pot ground lug securely attached to the preamp ground buss? YesNow try this...
Replace the 47K resistor that was removed from the board when you started this mod. Disconnect both INT pot wires at the board. Pull the Tremolo tube. This totally isolates the entire trem circuit from your amp. The amp is now a basic single channel AB763 with reverb but no tremolo. At this point, do you still have distortion? If so, then something has changed while you were doing the mod but it is unrelated to the mod. It's collateral damage. If this is the case, leave the amp wired like this until we solve the distortion issue.
I replaced the 47K, and disconnected the 50K pot at the board, and pulled V4.
I still have distortion
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I have taken a current voltage reading throughout, this amp has 6L6's installed. I believe I had 6 v 6 tubes when I took the original voltages.
The reverb circuit is really sensitive, I'll be installing the shielded reverb control wires shortly.
Let me know if you have any ideas based upon this current info.
Thanks
BV
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I still see the int pot connected!
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I still see the int pot connected!
I had put things back together to see where I was with tone and distortion, and to take a voltage reading with everything connected. I had previously disconnected the circuit as described and still had distortion after the Tremolo circuit was taken out of service.
I can disconnect the Trem circuit again if you have ideas for tests.
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Wire the trem circuit back up and make sure it's working. It's not a factor with your distortion. But, connect the end of the int pot to the board in a straight line fashion as shown with the green highlight in the attached pic. The way you have it routed now (yellow highlight) is bad. There is guitar signal on that wire and it needs to be kept away from other stuff. In fact, if you ever put shielded wire on the reverb pot wires it would also be a good idea to use shielded wire for the int pot.
Oh, and remove that 47K resistor again. It's not needed.
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I pulled the 47K resistor and installed a shielded wire on the intensity pot wire and it is flying on top. The tremolo works incredibly well, the amp is really quiet.
I replaced the two reverb control wires with shielded wire and that seemed to intensify the reverb circuit. It's get's very caverness very quickly. The distortion is more prevalent now.
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thinking out loud;
any chance the board stuff is be coming conductive or oddly capacitive :dontknow:
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thinking out loud;
any chance the board stuff is be coming conductive or oddly capacitive :dontknow:
That's Covid 19 incubating!
I'll clean it up, it was starting to bug me as well.
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:l2:
:occasion14:
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Symptoms keep changing
If you're bored can you recap, I'm at low notes distort, not sure what high notes do?
thanks
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Symptoms keep changing
If you're bored can you recap, I'm at low notes distort, not sure what high notes do?
thanks
Once I put everything back together with the shielded wires I started getting a little more distortion throughout.
The EADG strings are really affected more than the B and high E. The D string, if I slide from G to A it sounds like bacon frying.
Also, unless I'm hearing things, the scaping and scrubbing that I did in that area seemed to help.
Is this where an O Scope becomes really useful?
I think I will film it and post a video.
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sounds like bacon frying.
typically; arcing, bad solder
you should be able to inject a "pick your note" and make bacon sounds with a stick
take your time.
Is this where an O Scope becomes really useful?
not quite, but I'd be saving up :laugh:
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Here is a link to a quick video I did to identify the Tremolo performance and a quick highlight of the distortion
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Have you checked the output tube bias since you did this mod?
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Have you checked the output tube bias since you did this mod?
I'll check that here shortly, that's a good point. I'll also reflow some of the joints that I changed.
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Have you checked the output tube bias since you did this mod?
I had the bias a little low, I have JJ 6l6 GC, with a plate voltage of 450, I had it set for 42 mA, I bumped it up to 53 mA.
It actually sounds worse than it did yesterday.
I went through and re-flowed some components, I still have bad distortion.
Any ideas?
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It actually sounds worse than it did yesterday.
I went through and re-flowed some components, I still have bad distortion.
Any ideas?
Yes. Roll back to March 6. No Trem-O-Nator for you! :l2:
Seriously, put it back like it was. Still have bad distortion?
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It actually sounds worse than it did yesterday.
I went through and re-flowed some components, I still have bad distortion.
Any ideas?
Yes. Roll back to March 6. No Trem-O-Nator for you! :l2:
Funny guy!! It is kind of funny though, I was excited and the trem works so nice.
Seriously, put it back like it was. Still have bad distortion?
I had figured that might be the next step. If I still have bad distortion then I'll start getting bummed, this amp was really nice at one point.
I think I'll crank up the Dual 50 and Jam for a while. My Theater project got shut down today so it feels like 2007 with a twist!
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I think it will be good to get back to a baseline condition and evaluate the distortion issue. The mod is simple and easy enough to reinstall later. We need to know if the mod actually caused the distortion for you, or if it is truly just collateral damage and if rollback will cure the distortion. Rolling back should not be too difficult. Don't bugger up the trem o nator parts.
Don't forget to use your 250K int pot. And put that 47K resistor back if it's not worn out. :icon_biggrin:
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I think it will be good to get back to a baseline condition and evaluate the distortion issue. The mod is simple and easy enough to reinstall later. We need to know if the mod actually caused the distortion for you, or if it is truly just collateral damage and if rollback will cure the distortion. Rolling back should not be too difficult. Don't bugger up the trem o nator parts.
Don't forget to use your 250K int pot. And put that 47K resistor back if it's not worn out. :icon_biggrin:
3/4 the done, thanks for the 250K Pot reminder, I'll finish up with that everything tonight, and re-check in the morning.
I was so excited I bought a case of the Vactrol LED's! I thought it would be a slam dunk of swirl.
I bought enough parts to upgrade my Princeton and two Deluxe's so I should be covered.
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it feels like 2007 with a twist
:l2:
I was thinking more 1984, with twisted sisters singing do-wap :icon_biggrin:
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I was so excited I bought a case of the Vactrol LED's! I thought it would be a slam dunk of swirl.
I'm optimistic that you will still get to use them.
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The retro Mod work went well. I took my time and tried to be very accurate. The results did not turn out very well.
I have very bad distortion and I cannot get the tremolo to work. I replaced the footswitch jack back to the RCA, replaced all of the original components including the 250 kL Pot.
I went from having mild distortion to significant distortion.
So it is apparent that there is something I did to cause the original mild distortion, and I think I compounded it.
I'm having a Soup Sandwich for lunch.
I'll take a fresh voltage reading in a few after I take a break.
Update
I made a mess, some of my voltages are wonky, I have a place to start looking. I spent some time cleaning up the B+ Resistor Connections, the 1K Resistor connection was suspect.
Note: I picked up the turret connections at the dual .1 caps that were previously separated with the mod.
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I'm following this with great interest. I am not sure what schematic you are working off of? In it's current state as of reading this post, can you share a schematic of exactly what you have now?
Is it closer to the Hoffman schematic that Sluckey drew up OR closer to Sluckey's Tweed Deluxe but with tremolo added?
IF you found wonky voltages, that's certainly a good starting place to trouble shoot.
With respect, Tubenit
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Is the green column your current exact voltages? IF so, the LTPI V5-6 plate voltage looks way off.
Something has got to be amiss there? You might want to recheck that plate voltage on V5-6 and on V5-7 & V5-8 cathode? I am wondering if there is a bad connection on the pin or on the board that goes to pins V5-7 & V5-8? I'm wondering if a bad connection there is not drawing down the voltage on the plate properly?
With respect, Tubenit
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Is the green column your current exact voltages? IF so, the LTPI V5-6 plate voltage looks way off.
Something has got to be amiss there? You might want to recheck that plate voltage on V5-6 and on V5-7 & V5-8 cathode? I am wondering if there is a bad connection on the pin or on the board that goes to pins V5-7 & V5-8? I'm wondering if a bad connection there is not drawing down the voltage on the plate properly?
With respect, Tubenit
Jeff,
Thanks for the interest.
The current status and trouble shooting theory is to pull the Trem-O-Nator Mod and replace the original circuit. This was done to prove that I have a collateral damage distortion issue from the TON mode.
I am using the original Hoffman AB763 Schematic.
After I installed the Trem-o-Nator Mod I ended up with a mild distortion on the lower register.
It was agreed that I should replace the circuit to original as stated. I took my time and tried to be very accurate, but I fouled something up.
Currently, the amp is up and running.
The Green voltages are from last evening and I haven't done anything yet.
V5-6 and V5-7 and V5-8 are definitely wonky. It is confusing to see those voltages on V-5 way off, I hadn't molested anything on V-5, but I am never surprised of the results that I can produce. :laugh:
It is certainly a humbling experience. I am going to gear up and spend some time going over V-5 for starters.
I had changed the B+ 3Watt resistors twice and that move made me suspect the Power resistors.
Mode Voltages
A = 437 V
B = 436 V
C = 431 V
D = 418 V
Note, the amp was preforming very well and sounded fantastic before I hacked it up.
Thanks, BV
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Looks like the wiring to V5 socket is really messed up. Rewire IAW the layout.
I'd really like to see a bigger hi-rez pic that clearly shows V5 socket, the board, and all wires between the socket and board.
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I'd really like to see a bigger hi-rez pic that clearly shows V5 socket, the board, and all wires between the socket and board.
+1
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Looks like the wiring to V5 socket is really messed up. Rewire IAW the layout.
I'd really like to see a bigger hi-rez pic that clearly shows V5 socket, the board, and all wires between the socket and board.
OK
See below.
V-5 is the third photo, the last is V4
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Two more of the V4, V5 section
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If I'm reading your Vchart correctly it appears your bias is twice what it was, not sure if that matters, but maybe tweak it back to the "good times" :dontknow:
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If I'm reading your Vchart correctly it appears your bias is twice what it was, not sure if that matters, but maybe tweak it back to the "good times" :dontknow:
The good times are gone apparently. Turning the bias down created more distortion, cranking it up was better but I was about 100 mV.
After I took the photos I thought I spotted a couple of tube socket connections that didn't look great so I cleaned them up, but it didn't change the voltage readings or performance.
I have multiple passes through my wiring at V-5 and V-4 and I'm not finding any incorrect wiring so far.
Dinkyguitar should review this thread before he starts a JCM 800 on a PCB, my board is getting beat up now and I am concerned that I may have had a cold joint that caused the distortion and I have compounded it.
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guessing 6L6? 50mV seems good, 100mV might not be
since the trem is "gone", steal the tube and swap it in the PI slot.
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guessing 6L6? 50mV seems good, 100mV might not be
I have JJ 6L6 GC. I had a Plate V of 450 and I had the bias set at 53
since the trem is "gone", steal the tube and swap it in the PI slot. That was a great idea!! No change :think1:
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No change :think1:
ah, newbie, there is a change, it ain't the tube, check! :laugh:
you also wiggled all the pins good, so if by "no change", then we can make a small assumption (knowing the risks:)
the socket n wiring are maybe ok IF your voltages stayed the same.
what happens to the low plate voltage when you have the PA tubes out?
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AB763 wants a 12AT7 for the PI. If you gotta steal a tube then steal the reverb driver, which should also be a 12AT7.
And change the V5 wiring to agree with Hoffman's layout!
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No change :think1:
ah, newbie, there is a change, it ain't the tube, check! :laugh:
you also wiggled all the pins good, so if by "no change", then we can make a small assumption (knowing the risks:)
the socket n wiring are maybe ok IF your voltages stayed the same.
what happens to the low plate voltage when you have the PA tubes out?
With V1 thru V5 out I get 435 V
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AB763 wants a 12AT7 for the PI. If you gotta steal a tube then steal the reverb driver, which should also be a 12AT7.
I used a fresh 12AT7
And change the V5 wiring to agree with Hoffman's layout! I'm not seeing it, I have V5-6 and V5-1 tied to the .1 Caps in the PI
V5-2 goes to the 1m resistor.
V5-3 and V5-8 are tied together and connected to the 470 ohm resistor
V5-7 is tied to the small cap and 1m resistor.
I highlighted and traced it again a few times, I'm just not seeing an error at V5 wiring.
What looked incorrect to you?
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Sorry. Disregard. My eyes must be blurry.
Now measure resistance from pin 7 to chassis. Also measure resistance across the small cap (C23) that is connected to pin 7. What have you?
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Sorry. Disregard. My eyes must be blurry.
Now measure resistance from pin 7 to chassis. Open Load
Also measure resistance across the small cap (C23) that is connected to pin 7. What have you? Open Load
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Getting close! Both of those readings should be approx. 1MΩ. Check R44.
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Getting close! Both of those readings should be approx. 1MΩ. Check R44.
I am getting 1 meg while in circuit
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Check R42.
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Check R42.
21.8 K
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Recheck the resistance across the small cap (C23)
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Recheck the resistance across the small cap (C23)
Open Load
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You do realize that the 1M ans 22K resistors are directly across that small cap? But yet the 1M is OK and the 22K is OK. Resolder all four of those turret lugs and recheck the resistance across the small cap.
BTW, I can stay online with you for another 45 minutes if you want to stay online and solve this mystery.
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You do realize that the 1M ans 22K resistors are directly across that small cap? But yet the 1M is OK and the 22K is OK. Resolder all four of those turret lugs and recheck the resistance across the small cap.
BTW, I can stay online with you for another 45 minutes if you want to stay online and solve this mystery.
I'll take the slot of time, thank you. I took the readings without power. I'll float those turrets. I don't understand how I would show resistance in that cap?
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Please tell me you did not remove the cap to check resistance across it!
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Please tell me you did not remove the cap to check resistance across it!
No I did not pull the cap, I floated the turrets and got a reading of 1 meg from pin 7 to chassis and 1 meg across the cap. I'm putting the tubes back in to see where I'm at voltage wise. Pretty incredible CSI work
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That should fix the wonky voltages. Hopefully it will fix the distortion too. Still got 20 minutes. I'll be right here.
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Signing off. I'll tune in tomorrow. Hope you have some good news.
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Signing off. I'll tune in tomorrow. Hope you have some good news.
Great news! Distortion seems to be gone, I cranked it and it seems solid. The trem doesn't work, but I can see how destructive it can be to randomly refloat things.
The plate voltage is 436 and I set the bias at 48 mV. The voltages for V5 are back to normal. I posted the voltages for V-5
If we can conclude that the Trem-O-Nator was not causing the distortion, then I will take a break and then re-install the TON tomorrow after I file for Unemployment.
Steve, Jeff, Shooter, et al..thank you taking the time to guide me again. It's beer time
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Great news! Distortion seems to be gone, I cranked it and it seems solid. The trem doesn't work, but I can see how destructive it can be to randomly refloat things.
If we can conclude that the Trem-O-Nator was not causing the distortion, then I will take a break and then re-install the TON tomorrow after I file for Unemployment.
That is good news. Play the amp for a while to be sure you know how it sounds and be sure the distortion is gone. I never thought the TON mod caused the distortion. Always thought it was something unrelated that happened while you were doing the mod. That's called collateral damage.
Once you are happy with the amp again you can proceed with the TON mod. Hopefully it will go as expected this time. You can probably do it blindfolded by now! :icon_biggrin:
BTW, see the attached pic for the most logical reason that your trem is not working right now. It's not necessary to fix this unless you just want to be sure it works and get a fresh idea of how it sounds before proceeding with the TON mod.
FYI, that last pic you posted was the sharpest pic yet. Made troubleshooting much easier. I'll stay tuned...
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Hooray success!!!! :thumbsup:
Man, you stuck with it and your tenacity and persistence prevailed!!
I think the TON mod will work flawlessly for you and not cause any unwanted distortion.
Continuing to follow this with interest! Jeff
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It's beer time
:laugh:
that's why I quit talking last night! my "beer" is pretty stout :icon_biggrin:
way to hang in there on a problem, you're gonna be a rarity, you can play both in and out of an amp with confidence :laugh:
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Thanks again guys. The amp plays very well, so I think it has a clean bill of health to try and withstand another Mod.
Just got in from a deserted jobsite, weird feeling about that. I'll play it for a while and possibly start the ReMod this afternoon.
BTW, good eyes on the 4.7 K resistor Steve!
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I played the amp for about an hour and it seems fine. I will need to address a little overpowering Reverb or maybe the linear pot in the future. I can only set it on 2 before it gets really caverness.
I have an updated voltage chart for reference.
Steve, I have a question on the TON Hoffman layout. Should the .01 cap that is in series with the .022 be changed to a .022 per the Bandmaster schematic? I have attached the schematic behind the AB763 Layout.
I had used a .022 in lieu of the .01 in my previous TON mod.
Thanks
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Ain't no big deal. Either cap is fine. The .022 will give a slower speed (swamp), .01 will give a faster speed (Fender norm). If you want to get fancy then put a .01 on the board and use a switch to put another .01 in parallel to the onboard cap. I've done this on several amps. I didn't do it on the Bandmaster because I didn't want to drill any holes.
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The Trem-o-Nator Remod went swell!
No issues of distortion after a couple playing sessions.
The reverb has always been super sensitive where I can barley get to 2 before it goes into some deep caverns. I am using a 100K linear taper pot as designed. My 2nd Deluxe is like that as well.
Any advice on the Reverb would be splendid.
Thanks
BV
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Maybe try a 100KA reverb pot
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+1
Using a log taper pot is the best/easiest thing to do. Adding a dwell pot is the next best thing to do to tame the reverb.
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> I can barley get to 2 before it goes into some deep caverns. I am using a 100K linear
What does it do at "10"? Is it just A Whole Lot-t-t-t-t, or does it fall into the bowels of the earth?
If it is just WAY too much, take some gain out of the reverb path.
If the "10=Richard Dale" setting works but you can't get a subtle "air", use a Audio taper so "2" comes out smaller.
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When you get a chance make a sound clip that demonstrates the TON at several speed/intensity settings. Maybe that will tease Jeff enough to make him get off the pot. :icon_biggrin:
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+1 I'd love to hear a new clip! Something with intensity cranked up and the speed slowed down.
IF I may make a request, I'd like to hear something like this. :icon_biggrin: :icon_biggrin: :icon_biggrin:
&t=41s
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PurpleTele
fwiw
80% of my self imposed build errors have been in the TON circuit, did I catch your bugs :icon_biggrin:
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Maybe a little CCR too...
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I'm holding out for some 'lil wing with tremolo :icon_biggrin:
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....maybe a stupid question: :think1:
What can I do with the leftover triode? I wish I could get a bit of crunch out of the amp.....maybe using it as a cold biased stage to add some 2nd harmonic.
Is there a layout for the 2-channel....not so important, but would be nice to have and could save some brain-stretching :w2:.
ATB KH
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What can I do with the leftover triode? I wish I could get a bit of crunch out of the amp.....maybe using it as a cold biased stage to add some 2nd harmonic.
Is there a layout for the 2-channel....not so important, but would be nice to have and could save some brain-stretching :w2:.
Here's one...
http://sluckeyamps.com/misc/bandmaster.pdf
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...thanks Sluckey! OK, my amp will have the Reverb as well, but it's nice to add a 3rd stage to the Normal channel :-)
Best regards
KH
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...thanks Sluckey! OK, my amp will have the Reverb as well, but it's nice to add a 3rd stage to the Normal channel :-)
Here's a thread where the Trem-O-Nator was added to a Pro Reverb amp...
https://el34world.com/Forum/index.php?topic=24603.msg265118#msg265118
In reply #4 you will find the original Fender schematic/layout showing exactly how the mod was done.
Or maybe you prefer the Hoffman style layout... You can use the Hoffman board to build this. Turret layout is exactly the same. See attached...
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Dear Sluckey,
thanks a lot! I got a set of boards from Mr. Hoffman already, so I have a plan now :worthy1:
Best regards from Germany!
KH
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If you decide to do this please start a new thread and share your project with us.