I'm working on a YBA-1 presently which has an included schematic on the lid (thanks Traynor!). Unfortunately, part of it is torn off and missing, and there are a few inaccuracies (like cathode on V4 is labeled as pin 6). I searched high and low online for a proper schematic for this seeming strange model (has choke, 2 40mF/450V cans and that's IT for filter caps) to no avail.

So, I took the next closest one I could find. It was all munged up though, and you could barely read the values. There were smudges all over the place, and most values were literally unreadable. You could tell what type of component was what, but that was about it.

So, using photoshop, I painstakingly rebuilt the entire thing by hand. And now here it is. I will also email it to Traynor, as they don't seem to have this particular schematic in their possession, because I got the next-best-thing from a PDF Traynor sent me containing "every known revision".

Here it is for your downloading/viewing pleasure:

Replaced 2-prong cord (with 3 prong plug electrical taped onto it!)

Unwired ground switch (left intact)

Soldered ground to chassis (these chassis are so heavy my 40W iron wouldn't cut it so I had to resort to the propane torch!)

Replace 4M (!!) volume pots with 1M

Replace treble bleed cap with 100pF (from 1nF)

Full cap job going with F&T dual 50uf 500V Cans except 10@100V for the bias (up from 8@250V - what was up with that anyway??? Most times these were grossly under spec for voltage.)

Added a 220K bleeder resistor

Replaced 39k resistor with 10K in series with a 100K pot for variable fixed bias

Polished and retentioned input and speaker jacks

Cleaned pots and tube socket pins

Nice big American made Sylvania 6CA7s!

Clean and lots of room for the new caps to go in

And here's the finished cap job

Here's a list of what is required for a cap job on a late 60's Traynor YBA-1 (not to be confused with the YBA-1A!). Prices will be updated soon.

2x Dual 40@450V (Can) - or -

    4x 47@500V (Axial) - or -

    2x 100@500V (Axial)

    1x 47@500V (Axial)

2x 100@100V (Axial)

1x 125@16V (Axial)

Should you go with Can caps or modern discreet axials? Good question. Really, it's up to you. The can caps are more expensive, but can be more cleanly mounted. They are a little harder to install, and therefore harder to work with, but they will stay put forever, as they are soldered to the chassis, AND clamped.

can caps have several caps in one case

Axial caps are cheaper and lighter, and just as good electronically. They only downside is that they take up extra space inside the chassis and need to be tethered down with cableties or clamps. This is actually less work than changing a can cap, so it's more common to do this type of replacement. The real question is, how much of a purist are you?

Axial caps are much smaller and cheaper

Screen grid resistors of 470 to 1K @ 5W should be installed (2 required) if they have not been already as most of the early YBA-1's shipped without them.

60's-early 70's YBA-1

Mid-70's "pop-top" style YBA-1. 

Another Traynor YBA-1 video demo... this one shows everything from the "cleaner" nice, thick, meaty sound that this amp can make up to a nice growl.  Can't wait to get mine - did I say that already? :)

Big Cheers!  I get my Traynor YBA-1 guitar amp back this week... I bought it way back in high school and used it a TON in my high school and college bands.  It needed work for years and I finally sent it out to a guy who completely overhauled it and brought it back to life.   Can't wait to play it again!