Please Help Me Trouble Shoot 64 Bandmaster

[dumbassbob]

Bias cap OK, the 500 pF, big so what if it's off by a couple percent. Hi Voltage filter caps are likely OK but it MAY have been the transition from old barely working filters to new ones that's been foxing us.

Still suspecting those domino caps. If they went open circuit due to overhandling, tweaking the leads back & forth while removing, replacing, removing, replacing, that would give you a no-treble amp for sure. You could parallel or substitute with a 0.001 uF or any nearby value you have on hand.

I measure the bias V at the ends of those 220K's where they meet the caps, but it should be nearly the same at the point where they join. Also, I'd like to see a voltage measurement on each side of that 500 pF cap. Yes hand in a pocket or behind your back will keep a shock from stoppin' your heart, the last thing we need at at this stage, or any time for that matter. Ya gotta survive to enjoy your working amp, eventually, hope it's soon.

Would also be good to resistance check the volume treble & bass pots but let's find out what happens with these other tests first.

I was still going through the amp looking for anything different..The Amps Trannys and choak say 606-3-42 On the schematic the caps say 20-20-20- 525 and 60-350 60-350 Why are mine(2) 220uf@350 (1)40uf@500V. and (2)20uf@500v. Also the 40uf caps ground lead was touching the metal cover, I fixed it,And how do you know if the tube sockets are bad..Some of them really wiggle.. the 500PF is 500 They pulled the old one out ,it is 515pf, also the Domino caps are both 385PF...Thanks again,I will get back to you...

[Leo_Gnardo]

I was still going through the amp looking for anything different..The Amps Trannys and choak say 606-3-42 On the schematic the caps say 20-20-20- 525 and 60-350 60-350 Why are mine(2) 220uf@350 (1)40uf@500V. and (2)20uf@500v. Also the 40uf caps ground lead was touching the metal cover, I fixed it,And how do you know if the tube sockets are bad..Some of them really wiggle.. the 500PF is 500 They pulled the old one out ,it is 515pf, also the Domino caps are both 385PF...Thanks again,I will get back to you...

Looks like they beefed up your hi voltage filter bank. No problem there. Nor with the 40 uF ground lead touching the "bathtub". A little sloppy maybe but that end's already at ground potential, like the lid when it's bolted on.

Now those dominos at 385, even if there was no 220K draining some hi frequencies to perdition, the combination of 385 & 250 pF in series gives you an effective 150 pF, still enough to send some useful hi frequency content through to the treble pots but not near as much as just the regular 250 pF would. When you're measuring the dominos, you have them out of circuit, right? Just have to lift one end, no need to pull 'em all the way out.

If those wiggly sockets were all that bad, you'd hear some big time scratch, snap crackle pop as you move the tube around, with the power on.

When you get bias voltages & a voltage check on each side of that 500 pF let us know.

[dumbassbob]

The more I look at this amp the more I see where someone did a mod.. All the parts and transformers show it was built in 1963,But then I was looking at the Filter caps and saw two other resistors,So It has a AB763 Filter cap board,but the power tubes are wired like a AA763 Would this cause the Bias cap to blow 2 times,Should I rewire Power tubes to Ab763 spec....

[52 Bill]

The more I look at this amp the more I see where someone did a mod.. All the parts and transformers show it was built in 1963,But then I was looking at the Filter caps and saw two other resistors,So It has a AB763 Filter cap board,but the power tubes are wired like a AA763 Would this cause the Bias cap to blow 2 times,Should I rewire Power tubes to Ab763 spec....

I don't know if the filter cap board is original or not, but remember that often as new things were introduced, they would just be added to the amps regardless of the model number. The added balance/bleeder resistors on the first two filter caps cannot cause the bias cap to blow.

When the bias cap goes bad, what does it do, explode, leak, smoke, short, go open circuit? Please explain if you can. Over voltage, reverse voltage or worse yet, ac voltage applied to the bias cap can cause it to die quickly.

The added grid stoppers on the power tubes have already made the power tube circuit like the AB763.

[dumbassbob]

It has been so long over 21/2 years,and I didn't know anything about the inside of a amp back then..There was no burn marks,or explode..The "other tech"I took it too just told me that the bias cap was bad and replaced with a 100/100...I also think the OP trannie blew because it is exactly one year olded minus one week,I also think it doesn;t like all the over filtering (2)200uf @500volt (1)40uf@350 and (2)20uf@350... Thanks

[JoeM]

I don't understand "I also think the OP trannie blew because it is exactly one year olded minus one week". There's a new transformer in the amp? The over-filtering isn't likely to cause a problem.

[Tom Phillips]

...I also think the OP trannie blew because it is exactly one year olded minus one week...

…There's a new transformer in the amp?...

Wow. That’s a surprise after all this discussion to find out the Output Transformer was changed ~ 1 year ago. I kinda suspected that because of the wiring dress shown in the photos but I would have thought it would have been done long long ago since it wasn’t mentioned in the discussions over the last two years. That’s one of the reasons I asked for a photo of the whole transformer side of the chassis back in post #44.

Oh man! What else don’t we know about this story?

[The Dude]

Wow. That’s a surprise after all this discussion to find out the Output Transformer was changed ~ 1 year ago. I kinda suspected that because of the wiring dress shown in the photos but I would have thought it would have been done long long ago since it wasn’t mentioned in the discussions over the last two years. That’s one of the reasons I asked for a photo of the whole transformer side of the chassis back in post #44.

Oh man! What else don’t we know about this story?

Yep,......yet another detour. This thread started on the 18th. Any reasonably good tech could have this thing sorted out by now. Reiterating once again that there have been several here offering to have a look at this thing. DAB, you're willing to send it to GW several times- you're willing to send it off for a complete new board- yet, you're not willing to let one of the many qualified tech's on this site look at it? I don't understand this. Do you have some logical explanation? This thread, like the last one, seems like nothing but "tail-chasing" to me.

[dumbassbob]

I said different year trannies PT1963-OT 1964....I have learned more about my amp looking at it in the last 2 weeks then GW did in 21/2 years....I thought it was OK to ask questions here or is it a club for guys like that Dude to make shit remarks

[The Dude]

I said different year trannies PT1963-OT 1964....I have learned more about my amp looking at it in the last 2 weeks then GW did in 21/2 years....I thought it was OK to ask questions here or is it a club for guys like that Dude to make shit remarks

1) Apologies for obviously offending you. It was not my intent. I am simply curious why you haven't taken some of the offers to look at the amp. Possibly you have a good reason?
2) You did not just say "different year trannies". You said you thought the tranny blew.
3) It is definitely ok to ask questions here. That's what the place is for. That said, is it wrong for me to also ask a question?
4) It's not a club. I alone made the "shit remarks". I assure you no one else was consulted.

Again, my apologies.

[Leo_Gnardo]

Congratulations on post # 100, exactly where the last thread went off the rails. I'm officially tossin' in the towel unless this amp shows up on my doorstep. DAB I seriously hope you'll take up one of the offers of help. It sure would be good to see it workin' and know just WTF was the matter. Pick one and PM them, or me, get an address & ship it. We've all given it the best we could.
Don't take it personally DAB, sometimes I get things I can't make heads or tails of. Good ol' Fender amps, those, I can fix, 100%.

[dumbassbob]

Congratulations on post # 100, exactly where the last thread went off the rails. I'm officially tossin' in the towel unless this amp shows up on my doorstep. DAB I seriously hope you'll take up one of the offers of help. It sure would be good to see it workin' and know just WTF was the matter. Pick one and PM them, or me, get an address & ship it. We've all given it the best we could.
Don't take it personally DAB, sometimes I get things I can't make heads or tails of. Good ol' Fender amps, those, I can fix, 100%.

I just wanted to get into it so I could explain to a tech what I know,Like They thought it was a AB763..Gw would say all this tech stuff to me,and it was my fault,that the amp didn't
sound good ..My guitars were bad my OD pedal ect...I would love to send my amp out but I am still paying off the credit card for the two other "Oh we will make it sound great techs" Gw world class amp restoration yeh right,him and Futara amps in OC...Total $1485 So you can see I am nervious to send it out,and then be told It sound fine.....I only asked honest questions I didn't say I was smartass wiseass,but I do play really well,I dont think too many guys do both Tom Sholt of Boston was the only guy I know...I will go find another forum to ask some questions if it is too much for you ,What a joke I paid all that money to fender guru GW and Futara amps and I now could of done it)shotguned) myself

[g1]

Nobody here is wanting you to go ask questions at some other forum. Many of us are just dying to find out what the problem is with your amp, just like you want to find out.
Any of the guys here who offered to look at it would get it right, and at a very reasonable cost. And they wouldn't tell you it sounds fine if it didn't.
Have you ever did an A/B comparison with another amp of same year and model (or close?). This is a key issue, does the amp sound bad compared to a good working one? Or does it sound bad to you because something was different from the others before (a difference you liked), and now that difference is gone?

[The Dude]

I just wanted to get into it so I could explain to a tech what I know,Like They thought it was a AB763..Gw would say all this tech stuff to me,and it was my fault,that the amp didn't
sound good ..My guitars were bad my OD pedal ect...I would love to send my amp out but I am still paying off the credit card for the two other "Oh we will make it sound great techs" Gw world class amp restoration yeh right,him and Futara amps in OC...Total $1485 So you can see I am nervious to send it out,and then be told It sound fine.....I only asked honest questions I didn't say I was smartass wiseass,but I do play really well,I dont think too many guys do both Tom Sholt of Boston was the only guy I know...I will go find another forum to ask some questions if it is too much for you ,What a joke I paid all that money to fender guru GW and Futara amps and I now could of done it)shotguned) myself

Look, nobody (including myself) is trying to chase you off. I simply asked why you hadn't taken the offered help. If you can't afford it, fine. That answers my question. You could have just said that instead of responding as you did.

What frustrates me is that you find a problem, for instance the broken resistor mentioned at the beginning of this thread, yet there's been no report on if it's been replaced or what the effect of replacing it has had. You need to take this one step at a time and report back what your results are. Instead, it seems like before one thing is fixed and results are reported, we're on to the next "thing". You clipped out a cap. What result did you get? We're now talking about a potentially blown output transformer that may or may not have been replaced and may or may not be the right transformer and we haven't even gotten past the earlier potential problems. Any one small defective part can cause the amp to work incorrectly and you need to take it a step at a time. If you find a problem, fix it and let us know what if anything changed in how the amp works. Shotgunning the amp is not the way to do this. You could potentially replace every part in the amp and still have a problem. There could be something wired wrong, a broken connection, etc. It's really quite simple. Listen to what the guys tell you/ask of you- do it- and report back. That is the best way to get the result you want.

I'm also of the belief that you need to forget about what GW did or didn't do to the amp and think of it like any other broken amp. Continuing to obsess on his "work" will only get you frustration. I think we'd all like to see you get this thing fixed. We just have to stay focused on one problem at a time.

[Leo_Gnardo]

I will go find another forum to ask some questions if it is too much for you

Better have your cast-iron pants on. Any other forum will kick you around somethin' awful. Be aware first that members of other forums keep an eye on this one. Wherever you go, your story is already known. Hardly a place that's got more knowledge AND patience than right here.

You led us on a merry chase and after hundreds of well intentioned entries, oh now there's maybe a mod and swapped out OT or maybe it's blown or who knows what. Down the rat hole once again. Consider us out here, there's a limit to our patience.

What Tom Scholz has to do with any of this? Is it non sequitur time? Why not Bebe Rebozo. Mahatma Gandhi. Norton Nork. More like the Red Queen and the Cheshire Cat and who's the Mad Hatter - 10/6 and it's yours.

Please, DAB, pull up your socks and get on with it. The sad sack act is getting really old. You have genuine offers of help. Pick one and go with it. With very best wishes and hope for your amp's health AND yours, LG.