Yesterday I picked up a Traynor YVM-10L mixer with 240 watt internal power amp. It's a 10 channel mixer made by Traynor in 1976. I was told the power amp doesn't work, but the mixer is dirty but OK. Yep, that's what I found.
As I opened it up, an envelope fell out which contained 10 pages of hand-drawn schematics for the mixer section. Here are some of the photos I took of those pages. The others in subsequent posts. (Had to reduce the size to get them to fit.)
I wish I had the schematics for the power amp though, but searches on Google proved fruitless. I also couldn't find anything like these anywhere either, and want to make them available
Output uses 4 TO-3 MJ802 power transistors, and while testing, I found that 1 is shorted E-C. I hope that's all that's wrong. My wife thinks I should replace all 4, but for crying out loud, they are $4.60 each! ::) Well, she said I could if I wait until after Feb 1 (finances being what they are).
So, is my wife right? Is it worthwhile replacing all 4?
Also, should I replace the power supply caps? I say one guy comment that he was "recapping" his PS.
Oh, by the way, what's the best way to clean the zillion dirty pots on the mixer?
Thanks for any advice. Phil
Oops, typo: YVM-10L, not YVN-10L as originally posted...sorry.
Additional photos of other pages from the envelope.
Here are the remainder of the pages.
I say you replace one transistor. If it works, you have 15$ to spend of something fun. If not, you have to replace the 3 others anyway. Recapping is always a good idea on old stuff, especially the electrolytics. For cleaning pots you could try compressed air. It has done wonders for me.
Quote from: syndromet on January 29, 2009, 05:01:34 AM
I say you replace one transistor. If it works, you have 15$ to spend of something fun. If not, you have to replace the 3 others anyway. Recapping is always a good idea on old stuff, especially the electrolytics. For cleaning pots you could try compressed air. It has done wonders for me.
Thanks for the reply. I pulled all 4 out and tested the base-emitter junction voltage drops. 2 were almost identical (0.524v), but one was a little higher (I think about 0.65v).
I was thinking about being cheap and only replacing one, but then decided to save up and replace all4. I was kidding about whether to replace them all (as my non-technical wife suggested).
Compressed air is a possibility, but I was eyeing some chemicals like contact cleaner and hoping there was something better. On Google, I found "Slider Libe" or something like that. Probably better than electrical contact cleaner.
Do old electrolytic caps loose "capacity" as they age? Or are they subject to breaking down/leaking under voltage?
What about the little electrolytic caps on the printed circuit boards?
Thanks!
http://www.andrewsamplab.com/Cap.htm
This is ofcource some guy trying to sell his services, but it does say how old caps can affect you tone and stability of your amp.
For the pots, I sugest to first spray them with compressed air, if they are not sealed. Then you get a can of deOxit and spray the guts of the pot. If the pot is seales, let a lot of deOxit run down the shaft, and twist the knob back and forth several times. Do this a couple of times, and if that doesn't help, change the pot.
Beatiful piece of equipment. Is it a single 240W power amp or two 120 W units? In any case, you´ll find on the net the schematic of a Traynor 100 or 120 W power amplifier, with two MJ802 devices; it should help you repair the one you have, being basically the same.If you can´t, I´ll search it into my poorly organized files .
Quote from: J M Fahey on January 31, 2009, 11:18:05 PM
Beatiful piece of equipment. Is it a single 240W power amp or two 120 W units? In any case, you´ll find on the net the schematic of a Traynor 100 or 120 W power amplifier, with two MJ802 devices; it should help you repair the one you have, being basically the same.If you can´t, I´ll search it into my poorly organized files .
Thanks. I have not yet found a 100w or 120w amp schematic, but the 200w that I did find has different devices altogether than the YVM-10L. I understand from the Yorkville site and history write-up (http://yorkville.com/downloads/other/yorkvillehistory.pdf (http://yorkville.com/downloads/other/yorkvillehistory.pdf)) that the amp is the "YPM-250".
The amp is just a heavy single box inside the mixer compartment with two parallel 1/4" speaker outputs labeled "250W 4 ohm". The transformer is heavy-duty!
Here's a picture after I opened it up. The top of the amp case has the 120v fan on the back, and I moved it out of the way (behind the reverb unit mounted on the bottom).
I will continue the search now that I know that the YPM-250 is the schematic I want.
Phil
Well, I replaced all 4 output transistors (MJ-802), sprayed all the pots on the mixer with cleaner/lube, reassembled, and had problems.
I tested it briefly before assembly with an old speaker (just in case), and it seemed OK. But when I got it all together and hooked up my PA speakers, the volume was a little low, and when I got above 4 on the main mix, any input caused nasty, loud oscillations (about 80 hz or so) until I cut the main volume. I mistakenly thought it was a power amp issue.
I took it apart again, and while apart, I temp-wired a line-out from another mixer directly into the power amp input. Worked great! So I temp-wired the Traynor mixer up (see picture), and hooked up a couple inputs from my boombox to do some trouble-shooting, and it worked great too!
So I put it together, and it was bad.
So I pulled it apart, and tested again and while apart, it was fine again.
I must be routing the wires wrong or something when I put it together. I will trouble-shoot more when I have another day off.
This is a VERY old thread but i was able to locate the schematics from Traynor/Yorkville , the drawings are not hand made but std industrial drafts. So .. here we are :)
Thanks fuzzythebear :dbtu: :dbtu:
Schematics are ALWAYS useful.
Somebody else may need them today or tomorrow :cheesy: