Old Subject, New Needs---Fender Tremolo Tweaks(or Advent of the Tremo-Nator)

[Platefire]

Several years back I rebuilt an 1974 Pro Reverb Head AA1069 and converted it to Blackface AA165 circuit. It's working find except the trem circuit is thumping in time with the speed and the intensity needs to be stronger. Best I can tell the AA1069 and AA165 Trem circuits are identical. As I recall I changed out most of the caps, resistors and Photo Cell with new in the rebuild. I did try a new EH12ax7 v5 today and nothing changed. I have read about Service Bulletin #9 adding a .01 Mylar cap between cathode RC to ground and 10 Meg at photo cell lead connection to help thumping. For intensity improvement I've also read about on a 1 Meg resistor, reducing the value to 100K and also installing a 5 mm red or yellow LED in place of the cathode bypass cap/resistor but I got the feeling it was referring to a bias type trem, not a photo cell type???
Sluckey!!! Where art thou? Could use some good experienced instruction here on best fix for this circuit. Thanks, Platefire

[sluckey]

Read this topic and let me know if you are interested in doing this to your amp...

     https://el34world.com/Forum/index.php?topic=24334.0

In reply # 61 and 62 you will see how I did this to a '67 Bandmaster. Look at the simple schematic in reply #61. This mod can easily be done to your Pro Reverb for about $10.

[Platefire]

I'm definitely interested. A little hard to see as it appears a lot simpler circuit compared to original. I copied you schematic and picture. From what I can see, a whole lot of removal of existing parts. Just as a reference, attached is the AA165 schematic and Layout. Thanks, Platefire

[Platefire]

I've been studying it. It appears I just need to get rid of all the un-needed stuff related to the AA165 trem circuit and basically install in just like you have on your schematic. Not sure where to get the Vactrol VTL5C1? Looks like the only thing that takes direct DC voltage is the V5a plate. Guess the Vactrol will be running off cathode voltage. Last recorded voltage to that plate was 435. It also looks like I would need to change my trem switch plug to 1/4" and the jack to a 1/4" with switch. How it should fit and work is slowly sinking in!!! It's got a thick skull to go through

[sluckey]

Study the attached file. The schematic and layout should agree but if you spot any errors let me know. Look carefully at the layout. Some components have been removed, some values changed, and some added. Any questions?

VTL5C1 is available from AES...

     https://www.tubesandmore.com/products/optocoupler-vactec-channel-switching

[Platefire]

Wow, Double Wow! Thanks Sluckey! I've just glanced over it but everything looks right on. I'm getting excited about having great tremolo because I do use it on certain songs and at random when the urge strikes me for a certain part. I've got to go saw up an Elm tree that got blown over in the storm this weekend but tonight I will give it good going over. I see you changed the switch jack to a RCA,---right?? Platefire

[sluckey]

Yes, RCA jack. Just like your original circuit, you must use the footswitch to turn the tremolo on.

[Platefire]

I went over it with a fine tooth comb tonight and couldn't find anything out of order. Thought I had found something when I found the white wire from bias power supply disconnected but finally figured out it was supposed to be disconnected. Best I can tell, everything is jam up and jelly tight. Sure appreciate you doing that for me! It's going to make a much more easier installation with a clear picture to go by.

All I need to do now is make a parts list, check my inventory to see what I got and then order what I don't have. Think I will have everything I need save the Vactrol. I've already got it in a parts list with AES. Platefire

[Platefire]

Parts List Done. Sluckey your pretty much right with your $10.00 estimate in parts. The VTL5C1 is $8 plus shipping. I pretty much can say, I've got all the rest. The hardest part will be twiddling with that old board removing parts and working the new in. I know in taking my time and working it out will be fine. Still trying figure how to go under the board with the jumper from the 1M at cathode to Vectrol. There is two existing holes shown on layout by both connections that I may can use if I can fish it through. I'll figure that out when I have the board before me. My Hen scratching parts list evaluation is attached. If you see anything missed let me know. Thanks! Platefire

BTW-One mistake on my parts evaluation is, the tube gain stage used should be V5a instead of V1a:>)

[sluckey]

You may not need to move that 1M resistor. Look at the original layout. You'll see a 2.2M and two 1Ms connected together near the top side of the board. You must remove that 2.2M but you can probably leave both of the 1Ms right where they are. Don't forget to add that short jumper from the junction of the 1Ms to ground. You will still need a jumper between the plus side of the VTL5C1 to that 10K resistor. I'd probably just put it on top of the board. Layout is not critical.

One word of caution. Be sure to connect the LED side of the VTL5C1 correctly. Plus side (LED anode) must connect to the tube cathode. Get it wrong and you will probably need a new one.

[Platefire]

OK, Thanks for the pointers! Here is the data sheet on the VTL5C1. It shows the #2 lead + side. The negative side looks like it has a 45 degree beveled edge. So this data sheet should help me keep from getting it crossed up. Platefire

[sluckey]

Don't look for any bevels. Just go be the writing on the top. Looks like you will get a Vactrol brand so it will drop in exactly as I drew it on the layout.

[2deaf]

There is no need to fool with any under-board wiring.  Take the wire off of pin 6 and connect it to the eyelet that the cathode is connected to.  The VTL5C1 is mounted the other way around for this.  Attached is what I mean.  It is pretty much like sluckey's drawing with a 47K instead of 10K and the VTL5C1 flipped.  The unused under-board wires can then be clipped and capped-off.

[Platefire]

Hay 2deaf


I know Sluckey and you worked on this circuit together. I guess the different value plate resisters and cathode resister can be chalked up to personal tweaks? I started off just looking for the best tweaks to the old trem circuit but verrd off on this after Sluckey recommended it. All comments I read point to it as a winner, even better than the bias trem. So I'm going with it. Thanks, Platefire

[2deaf]

I know Sluckey and you worked on this circuit together.

This is sluckey's baby.  All I did was to suggest some different ways to turn it on and off.

I drew that diagram awhile ago and I just posted it to show how you can easily wire it without going under board.  Other than the values, I think the diagrams are the same except I use an existing piece of wire and he uses a new piece of wire.

The 47K came about when PRR questioned the 10K's ability to stop the oscillation.  I think we disagreed on the calculations, but I felt that the 47K would take less current from the LED than the 10K.  The 10K seems to work fine in tests, though.

The 220K was already there in the amp, so I left it alone.  It's not that I think a 220K is better than a 470K.  If I were you, I would go ahead and change it to 470K like sluckey has it.

I have a different mod that can use only the components and wire that exists in the amp plus a VTL5C1.  But that's a whole different thing and not really relevant here.

[sluckey]

I have a 10K cat resistor in mine and it works very well. The oscillator runs continuously but at a lower current when the Vactrol is switched out. I consider that a bonus. Instant on when you hit the footswitch. Kinda like leaving the truck idling rather than crank it up every time like the UPS drivers.   

[Platefire]

Put my order in this morning for the VTL5C1. This is probably way overkill but I also included a metal oxide 1 watt 470K resistor. I've got a .5 watt metal film radio shack one and I know it was a .5 watt carbon in there that I will be removing---so--ya'll can knock me in the head if I overreached. So I was hoping it would further ensure the safety my UPS ever idling ready to go circuit:>) Platefire

[sluckey]

Platefire, do me a favor. Don't replace that 220K with a 470K. Try the circuit with the 220K first and report your opinion. I really think it will be fine. Fender used a 470K on some trem circuits and a 220K in later circuits. If you are satisfied with the 220K just stick with it. I'm betting it will be fine.

Also, do this first...

You may not need to move that 1M resistor. Look at the original layout. You'll see a 2.2M and two 1Ms connected together near the top side of the board. You must remove that 2.2M but you can probably leave both of the 1Ms right where they are. Don't forget to add that short jumper from the junction of the 1Ms to ground.

Moving that 1M to the tube cathode was all about faster startup when switched on, but since your circuit will always be on, that 1M should work just fine connected to ground. Report your findings. You can always move the 1M later if you think it needs to be moved. I'm betting it will be fine.

I'm just trying to gather some more info about this circuit and you're the perfect guinea pig.   

[Platefire]

Sure! I can work it any way you think best. When I use this head I haven't been using the onboard trem because of its thumping and weakness. I use a pedal instead but I would truly like to get it working well where it would be usable. This Fender head was just a bucket of parts when I got it and someone had tried multiple mods to hot rod it and had trashed it terribly. So I put it back to stock as much as possible but put it back AA165 while I was doing it. So no problem about keeping vintage original correctness with this one. Just want it to be usable for my purposes. It will eventually end up in the hands of my children, grand children or Great Grandchildren. I do have a Great on the way:>) Platefire

BTW--good to be doing a little amping for a change, I miss it!

[Platefire]

Ok, there has been a lot of changes from when we started the original discussion as far as removal of old and installation of new. I just wanted to go over my present understanding of the way it now sits and you can tell me it my understanding is wrong.
1-Removal/De-soldering:
a-remove both V5's old cathode resistors and bypass caps.
b-Disconnect V5b plate, pin #6 wire to be connected to latter to V5a cathode eyelet.
c-Remove old photocell bug
d-Remove old 10M and 100K bug resistors
e-Remove 2.2 Meg resistor from board and also disconnect tremolo pedal wire from eyelet where the two 1Meg's are connected together.
f-Remove wire from V5b pin #7 and cap off
g-Remove V5b Pin #8 cathode wire from tube and board eyelet.2-Installation:a-Install VTL5C1 in old eyelets where bug was removed with plus (+) #2 pin to the eyelet that  previous pin V5b plate pin #6 wire was connected to.
b-Attach wire from previous V5b pin #6(plate) connection to V5a Board cathode eyelet. Connect all other    VTL5C1 leads to their corresponding eyelets.
c-install 10K resistor from board V5a cathode eyelet to eyelet where 2.2 Meg was removed from junction where the two 1 M's remain.
d-Install jumper wire from eyelet of junction of two 1M to adjacent ground eyelet.
e-Pull Tremolo pedal board wire through board access hole and re-attach above board to eyelet where    VTL5C1 cathode lead, pin #1 is attached to.

f-Set all leads to eyelets with good mechanical connections and solder all eyelets.

Check me out and let me know if I am on the right track? Platefire

[sluckey]

Sounds good to me. Post a hi-rez pic if you're in doubt.

[Platefire]

Well I guess the time to take pictures is before the soldering. If I can be that patient for a confirmation. When I get that far along I'm usually dieing to fire it up and see what I got. But I'll try! 

[sluckey]

Get the lead out and git r dun! We want a report.   

[sluckey]

I thought you were ready to solder yesterday. Hit a snag?

[Platefire]

I'm to have a Colonoscopy and EGD on the 23rd.  Tomorrow the 22nd a day of taking the prep getting all cleaned out😂. So I think I'll get this behind me before I dive in. Platefire

[2deaf]

I'm to have a Colonoscopy and EGD on the 23rd.  Tomorrow the 22nd a day of taking the prep getting all cleaned out😂. So I think I'll get this behind me before I dive in.

I wish you good luck on that and I hope they don't make you sweat it out for two weeks waiting for the results like they always do to me.

[sluckey]

Hopefully the "cleansing" will be the worst part of you procedures. Stay close to the house today! BTW, did you know the doctor uses the same hose for both tests? 

[Platefire]

Har Har Hopefully they will do the Esophagus first instead of last. More incentive to get the "cleansing " process done well!

 Last time I did this,  they gave me the Anesthesia and set me in a room in a wheel chair waiting to take effect. When I came to, I was in the same location sitting in a wheel chair. I ask them, "When are you going to do it"? They said Hay, it's over with. I couldn't believe it, I never knew nothing about the whole procedure. I liked that.

Even though I'm going through the prep process today, if I had the VTLSC1 part in, I would probably go ahead and get started. I'm kind of funny about getting started on something like this before I get the parts in because I have had orders that got messed up and have to take extra time to get it straightened out. I expect the part to be in latter this week. Platefire 

[Platefire]

Surprisingly my parts came in Monday's mail but I had other things I had to constipate--I mean concentrate on. I did a little de soldering this morning getting started and working it in between other stuff. I might draw a schematic of my last understanding of what was last discussed just to make sure my understanding is correct. Getting into the actual mechanics of making all the connections looking at my board situation, sluckey's and 2deaf's drawings, I get a little confused. So I'll do that soon as I can. Thanks Platefire 

[sluckey]

You had it all figured out correctly. Just follow your step by step plan. Oh, and post those high rez before and after pics that you promised! They may just save your ass later on. 

[Platefire]

Well to late, I done done it! This sketch is the last iteration I remember. When I finish with the removal, I take a picture and when I install the new parts and arrangement, I will take a picture. I an not sure about high res but I will try to make it clear as possible. Platefire


Edit:  I finished the de-soldering, removal and attached a pic. Everything good?

[Platefire]

Here is another pic showing V5

[sluckey]

30 more minutes and you should be tremolo swamp!

[Platefire]

Hey! Just got it installed about 9:15 CST. Well I had to mow two yards today, so just now getting to it!Man! that Tremo-Nator sure sounds Beautiful to me. Perfectly quiet with no extra artifacts in sound except great classic tremolo. Glad that old thumping is gone!  The speed and intensity seem to have more than enough range for anything I'll be doing. Great improvement. I'll take a pix of the finished work and post it later. Didn't have any problem with installation. Just took my time to make sure to get it right. Thank you sooo much. Ye Haw!!!

[sluckey]

[Platefire]

Thumbs up, All right! Here is the finish pics.

[sluckey]

Now you are the goto guy for fender trem mods. Gonna refer all inquiries to you. Get ready! 

[Platefire]

Har-Har and if they ask a question I can't answer, I'll just refer them to 2deaf and if 2deaf can't answer it , he will refer them back to you! So there is no way out sluckey, you are the Tremo-Nator man Wear it with pride.

[Huddy]

I've got a 74 Twin that had a tick that wouldn't go away after follow everything in the service bulletin - no dice.  Thought I'd give this a try.  Aside from fixing the ticking - It's pretty darn lush.  Couldn't be more pleased.  Thanks for this!