Traynor YBA1 Bass Master (1968) repair

[Leo_Gnardo]

Also, I got the last 80W iron they had yesterday, so this weekend I will start some real work

Good for you! You might already know but I'll recommend anyway, scrape or wirebrush the chassis where you intend to solder, some old fashioned solder paste flux (Nokorode is one popular brand) sometimes comes in handy, and of course good quality 60/40 or 63/37 solder. Kester 44 is the go to brand around here. Ersin is another good 'un. Have fun!

[Arhythmic]

Thank you for the soldering suggestions Leo_Gnardo! I will go buy some paste flux tomorrow and maybe some new solder.
By the way, if I will remove the transformer for straightening the brackets and for the resealing attempt, should I loosen the bolts a bit so the varnish penetrates better in between the laminations?

[Arhythmic]

Hello

So this weekend I put a bit of work into the Traynor (finally)!
First thing on the menu was the 3-prong grounded cord:



I had an extension cord in my stash that I used because it was a different color than the usual black (easier to identify in the power bar or in a low lighting situations), but I also noticed that it was ''hospital grade''. Now I can use it around hospitals: awesome

Then, there were those can capacitors and their attachments and grounding:



So, I just basically attached those clamp-rings with nuts and bolts instead of the sheet metal screws. I also cleaned and resoldered the connections a bit with my newly acquired 80W iron. This thing is really impressive...

I also installed the Master Volume kit from Kevin O'Connor, using the ground switch hole on the back that was no longer needed.

I removed the end bell covers from the transformer, inspected it, tightened the bolts, reattached and... the buzz is still present. So this week I will unsolder it, remove it completely and sumberge it into the spar varnish and let it dry for a couple of days. A couple of photos of the culprit:





To be continued...

[g1]

I would suggest re-wiring so the fuse is in series with the power switch and both in line with the 'hot' side of AC (black).
The neutral (white) should go straight into the transformer.
The old style of fusing the neutral is no longer considered acceptable as far as safety standards.

[Arhythmic]

Thank you G1!
I will correct it for sure during my next amp dive

[mozz]

While doing your spar varnish potting, it may be best to loosen the screws back up, dip or soak in the solution(how much time to soak?), then when you remove to let dry, tighten the screws back up.

[Arhythmic]

Thank you for suggestion mozz! Will do!
I have another question about the bass adjustement: a lot of people suggest lowering the value of the capacitor (C6 on the schematic, .1 400V) from .1 to .025 or something similar. I was wondering what if I put a variable capacitor of this sort instead (https://www.tubesandmore.com/product...365pf-variable) to be able to tweak that value to taste at any given times? Is that a bad idea?

[mozz]

Don't use that. It is meant for radio tuning. Try the 0.1uf, if your amp has flubby or too much bass, then reduce it to .047 or .022, those are standard values but you can try any value you want.

[Justin Thomas]

If anything, if you want variable cap, use a multi-position switch instead. And if you haven't seen the size of most variable caps, well... hope your chassis is about 4" deep, at least.

Justin

[Arhythmic]

Hello

So... I unsoldered and unmounted the power transformer from the chassis :



But prior to that, I went a bit nuts and identified all of the wires and their placements :



Then I unscrew the end bells, removed the bolts and nuts and diped it in the spar varnish:





Ooops!.. It is clearly not entirely submerged... the high tech solution!



After 2-3 hours of scuba diving, the time came to let it drip and dry:



After most of the varnished dripped, I put the transformer flat over a large container so the remaining varnish dries without forming drops.



Then I waited for 3-4 days for the varnish to dry completely, resoldered all the wires back (I also followed g1's advice and sent the neutral wire from the power cord straight to transformer and connect the black wire through the fuse), flipped the switch.... and...... it buzzed... I think it is quieter than before, but it is still there. This time I think that I will leave it as is, it works after all
Many thanks to J M Fahey and Archie Speed for suggestions about the dipping procedure however! I learned a lot!

[Arhythmic]

Oh and another funny thing happened I ordered some parts through Mouser: capacitors, pot, etc. Received my order, yay! Mounted the new pots for the volumes (I saw that a lot of people suggested mounting 1M insted of 4M), soldered the new 120pf capacitor on the bright channel, turn the amp on... the sound is clean... all the way up to 10... bridge the two channels together, both pots on 10... still super clean...

Then it struck me!.. I ordered 1K pots instead of 1M pots... *sigh*...

After all that I took a break However I came back and removed the accessory plug from the back, which was useless for me. I'm planning to mount the bias probes on a plate screwed with the original sheet metal screws instead:



But I'm not sure that I understand where to mount the bias pots physically and on the schematic... Even after reading Kevin O'connors' schematic and instructions...

[Arhythmic]

A little update to this transformer problem!
I finally bought another Traynor (YGL 3 mr. III from 1973) and was playing with it for a while. Meanwhile the YBA 1 was drying... Finally I played through it yesterday and the transformer buzz was gone!!
So probably depending on the quality of the varnish it can take a few weeks to dry completely.
It finally worked so thanks to everyone who suggested that method!