How long should grid resistors last?

[sluckey]

Filter cap for the node that feeds V1.

[pbman1953]

The cap in that position now is 100 uf/ 500v. Should I change it to a lower value closer to the requested 10/ 400v?


I have a 16/ 475v and an 80/ 500v

[pbman1953]

Anyone?

[shooter]

If you have limited experience in troubleshooting amps, or don't have the equipment, find a competent tech in your area, maybe offer a few bucks extra to "sit-in" and learn directly.


you've been all over the board for your stated problem that goes away when V1 is pulled.  If you want to do it yourself, replace every component associated with V1(shot-gunning) then re-evaluate

[pbman1953]

I will check the V1 with more attention.


As I discussed with Shooter, It seems that I've installed too many filter caps in this amp. I going back to his suggestion of 100, 100,47, 47 for the 4 stages.




Here are my questions-


1- for the 2 100uf's- should I use a 220k resistor


2- Should I rebias after all is back together?


Thanks

[shooter]

As I discussed with Shooter, It seems that I've installed too many filter caps

NOT, what I said or suggested

[pbman1953]

Now I'm confused because before I had 225uf/770v x 2, then 100uf/ 500v, 16uf/475v

[pbman1953]

I have to say with the 100 100 50 50 , I didn't have 47's, it's much quieter.

[proaudioguy]

What did you swap the V1 plate resisters to?  What did you put in place of the originals?  Metal film?  Double the power rating?

[pbman1953]

What did you swap the V1 plate resisters to?  What did you put in place of the originals?  Metal film?  Double the power rating?

All metal film closest to the originals.  Ed, from the forum , gave me a few changes value wise around the v1 (b) area

[shooter]

100 at 500 volts is under what I see the transformer putting out at 550.

LOOK at the schematic, the designer put 2 cap rated at 450 in series, that = 1/2 the total cap value (50uF)of the 2,  AND twice the VDC (900vdc)

[pbman1953]

You're right, good point.

[pbman1953]

So I put back the first  2 stages




550/385v and 550/385v in series for the 1st and 2nd stage




Sadly with the 100 /500v most of the hum was gone. With the big caps some hum returned

[pbman1953]

Since I'm working in the v1 area, I want to report the changes I made years ago. The changes suggested were to  resemble I think a Bassman preamp. I may be wrong on the brand but it's supposed to mirror another well known preamp.


Going left to right on the schematic-


r3- 1 meg
r4- 1 k
r12- 82k
c2- .01
c1- 220/50v
r43- 8.2k
second r4-off pin 7 of v1- 1.5k
c34- 16/475v
c9- 220/35v
r13- 15k
r15-130 ohm
r17 &r18- 220k
r24 & r25- 100k
r26, r27,r51 & r52- 4.6k




Is there anyone that wants to take a stab at this?

[pbman1953]

no help for me?

[sluckey]

Put everything back to stock. Traynor is a good amp.

[pbman1953]

Will do thanks!


Before I do a couple new things. There a pot control off the back panel as a mid range type control. I never really liked it so I removed it. The hum is gone!


But there's still some crackle. I think it's from one of the JJ's. Is there a test sequence to eliminate power tubes for issues?

[PRR]

> changes I made years ago
> no help for me?
> There a pot control off the back panel as a mid range type control. I never really liked it so I removed it. The hum is gone!

We can't see your amp from here. Who knew it had "changes"? Or a "mid type" pot? In back??

You know this amp better than anybody. I have to agree "Put it stock!!" And do GOOD work, work that Pete would be pleased to sell. Examine EVERYTHING for looseness and tarnish.

[pbman1953]

Well I put everything back to stock and I have no sound. The power tubes are working because I can  hear them as I tap the chassis.
I went over things many times and I know it has to be something simple.


Can someone send me a check list what to check for first. I can say that the voltages at each point are correct. I swapped out all 3 preamp tubes too.

[Gregwor]

Well I put everything back to stock and I have no sound. The power tubes are working because I can  hear them as I tap the chassis.
I went over things many times and I know it has to be something simple.


Can someone send me a check list what to check for first. I can say that the voltages at each point are correct. I swapped out all 3 preamp tubes too.

Use the half split rule. Input 1kHz. Use your scope to check for signal half way through the amp (between the preamp and power amp). If there is no signal there, scope half way through the preamp. Keep doing this procedure until you pinpoint where the signal stops. From there, check connections, component and voltage values. With that knowledge you can hopefully find the faulty connection or component(s) 

Greg

[shooter]

9 outta 10 it's always the last thing you did.


verify values, a 46ohm isn't good if it should be 460k ohm

[pbman1953]

You all make me think, I needed a voice of reason. But I'm an idiot. I had R3 off the input with a 41 ohm instead of a 470 k. Busted!


Need a suggestion because I don't have the value for c 21. for the bass expander. Plus conversion makes my head spin because I'm not used to it


All I have is  for small stuff is a .0018uf (measuring 1900pf)  and it's calling for a .02 pf.


Thanks

[sluckey]

Somebody is messing with you. Ain't no such thing as a .02pf cap in the guitar world. If you look at all the other "PF" caps you'll notice they used capital letters for all... except this one. It's a mistake. Should be .02µF. Look at this schematic...

     https://el34world.com/charts/Schematics/files/Traynor/Traynor_customspecial_yba3a_manual.pdf

[pbman1953]

Somebody is messing with you. Ain't no such thing as a .02pf cap in the guitar world. If you look at all the other "PF" caps you'll notice they used capital letters for all... except this one. It's a mistake. Should be .02µF. Look at this schematic...

     https://el34world.com/charts/Schematics/files/Traynor/Traynor_customspecial_yba3a_manual.pdf

You gave a good point. If you look at the schematic of the YBA 3 Super, which is the same design, but more power. That part is marked as. O2 with no letters after meaning it was microfarads after all.


Thanks!

[pbman1953]

Update- All's working but at one point I lost gain. The snap crackle pop is gone due to another bad JJ 6550. I'm using my back up set of EH el34's until I get new tubes. I'm thinking of going for another, used in the past tube, Tungsol 6550.


As far as the gain, that's back by comparing the YBA-3 Custom Special to the YBA-3A Custom Super. The 3 came out first and it seems that there were mistakes on the schematic. When I compared the 3 Custom's preamp to the Super's , which are the same, I saw slight differences in values. For the 3 Custom the r45 the value is 82k for the Super it's 4.7k, hence my gain returned with all the power.


Now I'm listening to this amp like when I bought it. This amp and the Super came out before the SVT. If you dig into some of the history, some say that Ampeg modeled the SVT sound after these amps. Which mean they are on the gutsy side. So I have one last question because the changes I came away from made this amp half way between that gutsy sound and a warmer amp. If I wanted to go back in that direction which parts would need the most attention. Which resistor or cap would have to be tweaked?


Thanks again for all the help!


 


Thanks