# Traynor Yba-1 modded mess



## 0rchard (Jun 14, 2020)

Hello all,

I picked up an old yba-1 on reverb a bit ago, and after checking out the internals on this thing I am completely baffled by what is going on inside.

I am nothing beyond a hobbyist when it comes to electronics and reading schematics is not my strongest skill but from what I can tell, this thing is a horrifying mess.

I would really appreciate some experienced eyes to let me know how far this thing is from stock and if I can un-mod it myself or if I should go to a tech and prepare to pay way too much.

There is a master volume where the ground switch was that I would like to keep, but that is about it.

-The choke looks to be in bad shape
-There is a sticker above the ext. Speaker out that says "line"
-the cap and pot values are all over the place


Any help would be so greatly appreciated

Thanks in advance













http://imgur.com/id%3DBW4PQCx%3Btype%3Dalbum


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## Verne (Dec 29, 2018)

To post imgur images, you have to right click COPY, then come here and right click PASTE.


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## davetcan (Feb 27, 2006)




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## Frenchy99 (Oct 15, 2016)

Choke was added, these don't come with one. Plexi mods most likely. The work is nice and clean. Full cap job. The volume pots must have been upgraded to 1 meg. No mess here...

Did you not get any info on the mods done prior to buying it ?

How does it sound?


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## jb welder (Sep 14, 2010)

Agree with @Frenchy99 , that is far from a mess. Or in other words, there are a lot worse than this out there. 

Can you post the schematic you are using and list the components that are changed value? Possibly it's a different version that the schematic you are using?
Looks like probably some type of PPIMV installed.


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## dtsaudio (Apr 15, 2009)

Looks typical of the builds of the time. The only mod I see that I don't like is the way the added choke is wired to those resistors. First off, why are the resistors there? Usually a choke is used in place of a resistor. 
If the resistors are needed, a small terminal strip should have been used to wire them to, and to support them.


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## tonewoody (Mar 29, 2017)

Not saying the choke is stock on this example but didn't early YBA-1's have a choke?


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## dtsaudio (Apr 15, 2009)

tonewoody said:


> Not saying the choke is stock on this example but didn't early YBA-1's have a choke?


The real early ones with the vacuum tube rectifier had a choke.
Edit - found schematics with solid state rectifiers and chokes as well.


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## loudtubeamps (Feb 2, 2012)

Looks a bit weird.....a bit hard to see but ..the " choke" leads both seem to be heading to the fuse, one lead should be tied to the filter cap, so I would assume it's not a choke? Dan, that would explain why the series resistors are still there and tied into the filter. Yes jb ...a post phase inverter volume control...I would insulate all of the the blocking cap leads connected to the stacked volume pot..What's going on with the 1 watter's on the speaker outputs?


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## loudtubeamps (Feb 2, 2012)

just looking on a bigger pooter screen... (the " choke") nope, x former bias supply.


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## davetcan (Feb 27, 2006)

Wonder what happened to the OP.


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## 0rchard (Jun 14, 2020)

Frenchy99 said:


> Choke was added, these don't come with one. Plexi mods most likely. The work is nice and clean. Full cap job. The volume pots must have been upgraded to 1 meg. No mess here...
> 
> Did you not get any info on the mods done prior to buying it ?
> 
> How does it sound?


No, unfortunately the seller was completely clueless. I asked if the amp was stock before purchase and the seller confirmed it was, even after I pointed out the master volume he said it was a "ground knob"
after the sale he offered a partial refund because of the misleading info.

The amp sounds alright in general but the bass is completely overwhelming, even at zero on the bright channel there is too much 'woofy' low end to handle, I have tried everything in terms of cabs and guitars to minimize it but it stays no matter what.


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> Looks a bit weird.....a bit hard to see but ..the " choke" leads both seem to be heading to the fuse, one lead should be tied to the filter cap, so I would assume it's not a choke? Dan, that would explain why the series resistors are still there and tied into the filter. Yes jb ...a post phase inverter volume control...I would insulate all of the the blocking cap leads connected to the stacked volume pot..What's going on with the 1 watter's on the speaker outputs?


I was assuming this was to create the line output


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## dtsaudio (Apr 15, 2009)

loudtubeamps said:


> just looking on a bigger pooter screen... (the " choke") nope, x former bias supply


Loud, you're right. I missed the black wires leading to the fuse holder at the back. He still should have used a terminal strip to wire that.


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## 0rchard (Jun 14, 2020)

jb welder said:


> Agree with @Frenchy99 , that is far from a mess. Or in other words, there are a lot worse than this out there.
> 
> Can you post the schematic you are using and list the components that are changed value? Possibly it's a different version that the schematic you are using?
> Looks like probably some type of PPIMV installed.



That is reassuring, thank you. This was the schematic I had pulled up

I appreciate all the help and replies


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## loudtubeamps (Feb 2, 2012)

0rchard said:


> I was assuming this was to create the line output


yup...initially thought it was a 2k7 to ground. 270 ohms ...a bit hot for a line out, I'm sure it works fine.


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## jb welder (Sep 14, 2010)

I'm going to say that is not the right schematic, based on loudtubeamps observation about the extra transformer.



loudtubeamps said:


> just looking on a bigger pooter screen... (the " choke") nope, x former bias supply.


This must be one of the versions with the bridge rectifier (rather than full wave) and no CT at the HV winding. Likely the power transformer was replaced with one that does not have the bias winding so they added another transformer to obtain AC for the bias circuit. You can't get the bias source like the other versions that have the CT on the HV winding.
@Orchard do you have the serial # and have you dated the unit?

pg.7,8, or 9 of linked file is best guess for schematics: http://www.lynx.net/~jc/YBA1Schems.pdf


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## loudtubeamps (Feb 2, 2012)

0rchard said:


> No, unfortunately the seller was completely clueless. I asked if the amp was stock before purchase and the seller confirmed it was, even after I pointed out the master volume he said it was a "ground knob"
> after the sale he offered a partial refund because of the misleading info.
> 
> The amp sounds alright in general but the bass is completely overwhelming, even at zero on the bright channel there is too much 'woofy' low end to handle, I have tried everything in terms of cabs and guitars to minimize it but it stays no matter what.


I would replace the cap feeding the input of the phase inverter now a .1 with something in the range of .001 to .005 and the other .1 ...replace with a .02 +-


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## 0rchard (Jun 14, 2020)

jb welder said:


> I'm going to say that is not the right schematic, based on loudtubeamps observation about the extra transformer.
> 
> 
> 
> ...



Serial # 131500 
I wasn't sure if this was to be read as a 4 digit. Because no source lists anything about 6 digit serial
also has "D. HUSTON" scratched in to the rear plate. Assuming this was the original owner.

Couldn't get the schematic link to work on my end


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## loudtubeamps (Feb 2, 2012)

jb welder said:


> I'm going to say that is not the right schematic, based on loudtubeamps observation about the extra transformer.
> 
> 
> 
> ...



yup jb...page/diagram # 4 ^^^^^^^^^^^^^^^^^^^^^^^^^^
showing the 470 ohm /10 watt series resistors in lieu of a choke. The bias power supply....an add on for sure. Pretty sure the rectifier diodes have been replaced.


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## loudtubeamps (Feb 2, 2012)

0rchard said:


> Serial # 131500
> I wasn't sure if this was to be read as a 4 digit. Because no source lists anything about 6 digit serial
> also has "D. HUSTON" scratched in to the rear plate. Assuming this was the original owner.
> 
> Couldn't get the schematic link to work on my end


try this one>>>>> Traynor Amplifier Schematic Archive


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## loudtubeamps (Feb 2, 2012)

any chance of some pics. top side showing transformers?
I gotta' get out more.


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## loudtubeamps (Feb 2, 2012)




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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> any chance of some pics. top side showing transformers?
> I gotta' get out more.


Absolutely!


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> try this one>>>>> Traynor Amplifier Schematic Archive


Works! Thank you


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## loudtubeamps (Feb 2, 2012)

0rchard said:


> Works! Thank you


(Y) transformers look original. These did draw power for the bias from the B+ Looks like they ripped out the original bias supply circuit and replaced it with the separate power supply.


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> (Y) transformers look original. These did draw power for the bias from the B+ Looks like they ripped out the original bias supply circuit and replaced it with the separate power supply.


Do you know what the reasoning behind this could have been?


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## Frenchy99 (Oct 15, 2016)

OK, its a March 1971 unit based on the transformers.

Bumper version of the YBA-1, no choke on these. Could the additional transformer be to balance the bias ??? I had this in a Garnet head 2 years ago...


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## jb welder (Sep 14, 2010)

0rchard said:


> Couldn't get the schematic link to work on my end


The forum software breaks links that are not https. If any links or pics on the forum don't work for you, look at the address and remove the s from https so it says http. Then it should work. It's super annoying.

If this thread were in the 'maintenance and repair' section we would be able to directly upload schematics. Maybe a mod could move thread to that section? @davetcan ?


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> I would replace the cap feeding the input of the phase inverter now a .1 with something in the range of .001 to .005 and the other .1 ...replace with a .02 +-


I will try this asasp and let you know!


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## jb welder (Sep 14, 2010)

loudtubeamps said:


> yup jb...page/diagram # 4 ^^^^^^^^^^^^^^^^^^^^^^^^^^


Actually not pg.4 in that package I posted, but pages 7,8, &9. And the one you posted in post #23.



loudtubeamps said:


> These did draw power for the bias from the B+


The A1310 is in your schem. post #23. It does not get bias from the B+ but has a bias winding. Here's the Hammond replacement:
Yorkville Sound/ Traynor Bassmaster YBA-1 (Guitar Amp Replacement)

Not sure why they are not using the bias winding in this unit. I'll assume it has gone open. If it shorted, the rest of the transformer would not work.
The blue wires for that bias winding are probably clipped off or disconnected and tied off somewhere under the transformer.
So instead of replacing the whole PT, they just added an extra little transformer for the bias.


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## davetcan (Feb 27, 2006)

jb welder said:


> The forum software breaks links that are not https. If any links or pics on the forum don't work for you, look at the address and remove the s from https so it says http. Then it should work. It's super annoying.
> 
> If this thread were in the 'maintenance and repair' section we would be able to directly upload schematics. Maybe a mod could move thread to that section? @davetcan ?


done.


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## 0rchard (Jun 14, 2020)

jb welder said:


> Actually not pg.4 in that package I posted, but pages 7,8, &9. And the one you posted in post #23.
> 
> 
> The A1310 is in your schem. post #23. It does not get bias from the B+ but has a bias winding. Here's the Hammond replacement:
> ...


At this point with the transformer I'm thinking I should probably take it to a tech. Definitely going to go ahead and replace the transformer -thanks jb for the link

Any opinions on whether I should throw in a choke as well to tighten up while I am at it?


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## loudtubeamps (Feb 2, 2012)




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## loudtubeamps (Feb 2, 2012)

0rchard said:


> At this point with the transformer I'm thinking I should probably take it to a tech. Definitely going to go ahead and replace the transformer -thanks jb for the link
> 
> Any opinions on whether I should throw in a choke as well to tighten up while I am at it?


I would replace x former only if the added bias supply is not stable.
Re: Choke, your call, I would have no problem leaving the series resistors in. 
Some fairly high end amps out the that are chokeless.


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


>


Wait, this says bassmaster mark II on the schematic


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## jb welder (Sep 14, 2010)

0rchard said:


> Wait, this says bassmaster mark II on the schematic


Yes, that is the MKII.
The one he posted back in post #23 is correct and shows the transformer part # A1310.


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## jb welder (Sep 14, 2010)

Also not sure why you want to replace the transformer. It will be very expensive and is not really needed unless there is some problem with the bias circuit as @loudtubeamps mentioned.


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## loudtubeamps (Feb 2, 2012)

jb welder said:


> Actually not pg.4 in that package I posted, but pages 7,8, &9. And the one you posted in post #23.
> 
> 
> The A1310 is in your schem. post #23. It does not get bias from the B+ but has a bias winding.
> ...


yup jb , seems odd that someone would go to the trouble of clipping and hiding the blue bias feed. I notice the feet on the mains x-former have been modified, wondering if the x-former broke free during an impact and broke the bias feed wire....anywhoo...we're done I think. Cheers!


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## 0rchard (Jun 14, 2020)

loudtubeamps said:


> yup jb , seems odd that someone would go to the trouble of clipping and hiding the blue bias feed. I notice the feet on the mains x-former have been modified, wondering if the x-former broke free during an impact and broke the bias feed wire....anywhoo...we're done I think. Cheers!



Yes, this clears up everything. Thank you all so much!


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## 0rchard (Jun 14, 2020)

Hey all,

Following up on this thread with an update.

After changing cap values and seeing no change in the darkness and extreme low end coming out of the amp and spending hours comparing similar models, I found out what was really the issue:
It seems like when the amp was 'repaired' and tinkered around with at some point, the bass pot was somehow reversed, by this I mean that my trying to get rid of excess bass by leaving the knob all the way down was actually maxing the bass. In complete defeat I dimed the knob today and immediately the amp tightened up. This thing sounds incredible now! Much better headroom for beautiful cleans, and gorgeous crunch to distortion tones.

Thank you all so much for your help, it seems like this was a fluke/operator error issue after all.


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## traynor_garnet (Feb 22, 2006)

0rchard said:


> Hey all,
> 
> Following up on this thread with an update.
> 
> ...


My 1965 Bassmaster had exactly the same problem! Last month, my tech was trying to address my ‘too much bass’ complaints when he noticed the bass pot was wired backwards. He said it looked like it left the factory like this, meaning that for 55 years the amp was wired incorrectly!

It sounds much better now . It’s my second 1965 bassmaster and I may sell it, but what a bizarre coincidence between our amps.

TG


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## bzrkrage (Mar 20, 2011)

traynor_garnet said:


> the bass pot was wired backwards.


Well, that was the week Traynor had the "work experience" kids do some on hand training. 
Glad you boys found the problems!


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## MarkM (May 23, 2019)

Or the dyslexic guy worked there?


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