Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Shack on March 17, 2016, 10:01:48 pm
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with the PR built but no footswitch, will there be no sound? I still have to buy reverb tank and cables.....but the rest is done and powered up nicely, voltages looked good. will I need to wait for reverb parts and /or footswitch to hear it?
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will I need to wait for reverb parts and /or footswitch to hear it?
Not if it's wired correctly.
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OK then ill figure it out, it was kind of late. Usually with me its a jack wiring issue.
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OK, I do not want to be a pain, so ill explain where im at....
I thought either speaker or input jacks, because I wasnt hearing any thing at all....so I rewired speaker jack first.....to one jack....no difference. I dont want to do that to input jacks, because they are a pain and seem to be wired right as well.
What I noticed is that even though all filament tabs read 3.3 or so AC volts to ground, my V1 is not heating up at all.....and the soldering job on pins 4-5 is messy.....if that blob hits ground can I still see the right voltage and have the tube not work and no sound.....im gonna clean that up while I wait.
I am trying to go through all the troubleshooting stuff without asking for help, because I know that most issues are just a simple mistake.
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my V1 is not heating up at all
That will certainly cause an amp to produce no guitar sound. It's better to measure filament voltage with both probes directly on the heater pins (looking for 6.3vac), not from one pin to chassis.
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Did you get that white (grid) wire properly routed on the RCA jacks? Just wanted to make sure before you actually get her up an running.
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yes, I fixed that.....and ill report tomorrow on the filament thing....need to get that V1 running b4 troubleshooting further. I did start measuring that way Slucky. for some reason the filaments on V1 socket not working right. ill dive in further tomorrow
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OK, got filaments working, and the speaker jack seems fine...im not sure how to check out the input jacks without ripping them out, and its tight in there,lol...
My B+ on the plates of V1 were way high when filaments werent working, but settled down to 156 volts when they were....so all good there...
Bias seems to be good and adjustable at times , and then not so well, multimeter or what, I dont know, but.....at the moment I seem to be getting minus 140-150 volts on the grids of power tubes and that wasnt there before....
Im still gonna keep on trying to figure it out, the education of troubleshooting is priceless, but it is frustrating.
Was thinking about adding a single input jack to the ext speaker hole that I left vacant for now to see if my input jacks are ok or not . I know that this build is close, just not sure what is slowing me down, every time I try to measure and adjust power tube bias I get good readings one time and off the wall next time, and the tubes look and feel fine.....maybe my multimeter is psycho, dunno
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im not sure how to check out the input jacks
I check mine by plugging in a guitar.
Bias seems to be good and adjustable at times , and then not so well, multimeter or what, I dont know, but.....at the moment I seem to be getting minus 140-150 volts on the grids of power tubes and that wasnt there before....
-140 volts bias is enough to make that amp be very quiet. It should be about -30v to -36v.
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it was there b4 I fixed the filament
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I check mine by plugging in a guitar.
I did that too.....so your saying thats my problem?
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I check mine by plugging in a guitar.
I did that too.....so your saying thats my problem?
No. I'm saying "I check mine by plugging in a guitar". But you have bigger issues now.
it was there b4 I fixed the filament
I can't think of anything you could have done while fixing a dead filament on V1 that would have caused your bias voltage to jump up to -150v. The only way I can think of to have that much negative bias would be to have a very low value resistor for the bias range resistor or that resistor is shorted out. Your bias filter cap will be dead shortly if you don't get this fixed. Do you trust your meter? It could be lying to you.
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thats what im worried about
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so by turning the pot, I got it to 30 v.....-30 with red on chassis and black on grid......does that sound right?
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so before I head out.....I think my bias pot isnt soldered in well, so, between the filament issue and that....maybe thats why my bias is screwy....and I asked about the input jacks, cause I hate the thought of having to tear them out to redo with the tight space if there is an easy way to check, thx
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after resoldering the bias pot and redoing the filament....the bias is under control and I have faint sound...poking around didnt help me find anything, but im done for the night and im happy with progress. ive probably got something else not soldered well, but the faint sound may be that the input jacks are ok, maybe not. im pretty sure the amp is wired well, but wouldnt be surprised of anything at this point.....thanx for listening
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.....-30 with red on chassis and black on grid......does that sound right?
No. With black lead on chassis and red lead on the grid your meter should read -30. This assumes you are using a digital meter and it has auto polarity. Which meter do you have?
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gotcha...I have 2 digital meters....al old sears and an EXTECH meter that my son got from Boces class......I think the old one dont have auto polarity, because I used the newer one this morning and it is as you said.
Well getting some weak sound out now, but can hear tremolo too, good sign....so im gonna have to check all my solder joints now, as it seems all issues im having stem from that.
thank you again Slucky :worthy1:
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What kind of solder are you using? Can you post some hi-rez pics?
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I will post pics , and I use rosin core solder....I used the lead free stuff on the 5E3 and actually, I bought the regular solder from Walmart.
I was poking at all my socket, wire and component connections for any more poor solder joints, and what I just discovered was the ground wire from the filter cap can to the board is not only a bad solder joint but it actually came loose....wont be able to resolder it til after band rehearsal, but maybe that will get me one step further to a bug free amp :think1:
I am such a noob , lol
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Keepin my fingers crossed for ya. You are almost there. Your gonna have a big smile on your face soon.
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... I use rosin core solder....I used the lead free stuff on the 5E3 and actually, I bought the regular solder from Walmart. ...
Lead-free stuff is horrible; it takes much more heat & flux to melt & flow. I'd suggest 60/40 solder (the 63/37 stuff is essentially the same). Maybe this is the "regular solder" you're referring to.
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im gonna order me a roll of the 60/40 , because the walmart stuff runs out fast... but I think it is the same.....the lead free stuff was a nightmare....
Ill be good ats.....im patient, and the knowledge im getting here is as valuable as the amp will be, thanx to the patience of the people here
I know I ask alot of dumb questions, but I want to always be sure im right