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Post subject: Old Traynor YVM-6 PA/Mixer
Posted: Thu Aug 02, 2018 9:39 am
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Apologies in advance for a non-Fender post...
I picked-up this old Traynor PA/Mixer last night for $20 CDN.
It works...except the reverb. I opened it up and shook the dust out, and tightened down a few screws. It smells like an old dog...but otherwise sounds OK with a guitar.

I will try to get the reverb working as it is a long-spring Accutronics.

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Fri Aug 03, 2018 12:45 am
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Traynor are nice stuff, great Canadian amp. I fix few of them all tubes, not solid state.

Schematic here ;
https://el34world.com/charts/Schematics ... r_yvm6.pdf

Touching reverb recovery input ( C30 on shematic ) with you finer you should hear a sound if recovery working.


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Fri Aug 03, 2018 4:31 am
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Thanks Stratele.
I'll try the finger tap test.
The amp doesn't have the Reverb foot switch. So that could also be the problem. It is a 1/4 inch jack input...so I'll have to look around for something compatible...or build one.

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Fri Aug 03, 2018 6:04 am
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The reverb FS is to stop the reverb. No FS needed to put reverb On.

You only need single On/Off ( push On /push Off ) switch with a guitar cable or any good shielded cable


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Sun Aug 05, 2018 5:52 pm
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I opened the amp up and took it all apart.
The Reverb Tank, Accutronics 4FB2B1C two spring, had loose wires off the transducers, and loose wires back at the PC Board on both the input and output.
Re-soldered everything. All working now.

The ground pin had been snapped off the plug, so I replaced the cord as well. Burnt my nose on the hot iron...LOL... :oops: :lol:

I am wondering why the schematic shows 240V 50Hz as the input. It work as is. FYI the schematic was also pasted inside the cabinet. Same one as the scan that Stratele52 posted.

I can post pics of the innards if anyone is interested.

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Mon Aug 06, 2018 1:11 am
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BasementBob wrote:
I opened the amp up and took it all apart.
The Reverb Tank, Accutronics 4FB2B1C two spring, had loose wires off the transducers, and loose wires back at the PC Board on both the input and output.
Re-soldered everything. All working now.

The ground pin had been snapped off the plug, so I replaced the cord as well. Burnt my nose on the hot iron...LOL... :oops: :lol:

I am wondering why the schematic shows 240V 50Hz as the input. It work as is. FYI the schematic was also pasted inside the cabinet. Same one as the scan that Stratele52 posted.

I can post pics of the innards if anyone is interested.

-------------------
I am wondering why the schematic shows 240V 50Hz as the input.

Yes, it is funny look shematic show it was built for european market. Never know about Traynor in Europe

It work as is. FYI the schematic was also pasted inside the cabinet ; Traynor do that on all ther amps

You do a good job :)


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Mon Aug 06, 2018 8:58 am
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Thanks Stratele,

The output transformer is a Hammond (?) A1335 not the A1345 shown on the schematic...So maybe they were thinking of an export version...but I assume this is Canadian domestic model.

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 12:05 am
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There is no output transformer on a SS amp. Thats the power transformer
The back plate indicates 115 vac so you're good to go with it
You can reduce preamp hiss by changing out r1 560 k with a low noise metal film resistor of the same value
But the main stage is a relic from the earliest days of SS amps. It uses the same transistor complement as the famous Acoustic bass amps.
These early RCA transistors are obsolete and irreplaceable. Its possible they're all in good shape, but unlikely. The gain of the transistors rises from 40 hfe to 200hfe as they age and send the amp into an unbalanced signal and the bias runs away.
If you look at the schematic on the power stage at Q17. Its an rca 40408, unobtanium and irreplaceable. It runs continuously at half power and cooks the little heat sink around it. Its the hardest working semiconductor in the entire amp and gets real hot even with no sound going through the amp.
There are two .6 vdc voltage specs near Q17. One is the voltage drop base to emitter. Put both voltmeter leads across r66, the 680 ohm resistor. Its grey-blue-brown stripes identifies it. This ensures a good DC balance for the main stage.
Next, put the positive voltmeter lead on the end of R67 Black-black-brown 100 ohm that does not go to Q17. The black probe goes to ground. If these voltages are off by more than 50%, that transistor is living on borrowed time and it will take down the entire main stage when it goes.
You can lower the value of r66 to bring it down to .6 vbe. This will help the dc offset, but it will still have too high a bias. If the bias is too high, you need a new 40409 in Q22. But its also irreplaceabe.
If the voltages are right on, then maybe you got an old cream puff and it could sound good for a long time. Good Luck.


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 2:06 am
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TimsAudio wrote:
There is no output transformer on a SS amp. Thats the power transformer
.


Shematic show very well no Output Transformer

ImageCapture d’écran 2018-08-08 à 05.04.27


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 4:14 am
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Great information. I'll run those diagnostics and replace any needed parts.

So far in limited use, it is sounding fine with minimal hiss. The Reverb is nice. Pots are crackly but nothing bad. All the pots seem to have seen use.

The machine looks like it was well used, and has had maintenance of a few parts in the past. Probably out of someone's Sunday school P-A or a cheap polka bar.

I like it!

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 4:24 am
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Pots are crakly ! You mean they makenoise when you turn them ?

Dirt ? Use Deoxit contact cleaner, cheap one may not do the job.

Or leaky capacitor.


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 8:56 am
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I recommend replacing all the big ps electrolytic caps and the r1 previously mentioned. Clean the pots. Don't try finding replacements. If they are still crackly replace the small electrolytics as well.
Do not attempt replacing semiconductors unless they are the original numbers. The substitutes listed online don't work and will likely make it worse. When these amps were made, semiconductor science was in its infancy. The silicon material limited the gain of the transistors. Almost all modern transistors have too high hfe to be used in this amp.
Also,its primitive design relies on each transistor having the correct hfe to balance the main stage push pull output transistors. The 40408 and 40409 are particularly picky there. If they are out of spec and it runs as reported, just enjoy it till it dies. IMHO, its not worth the trouble to fix. But if you just make those measurements, it will tell you a lot about the health of the amp.


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 8:08 pm
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Thanks Tim. So much helpful information and advice.
This forum is amazing.

The amp is running nicely and isn't very noisy or much hissing. A bit more hiss when the Reverb is turned up. Nothing horrible.

There are over 40 pots...a few haven't likely been used in a while...so they have a bit of crackle and pop. I expect a bit of Deoxit would help...but again, nothing offensive.

As I mentioned the amp has had a few parts swapped out for maintenance. I will get to the big caps and the resistors as suggested. I'll run the other diagnostics as well. Otherwise I just plan on playing it for kicks...it sounds good.

For $20 CDN cash, from a basement barber in a sketchy part of town...with no questions asked of the the old guy I got from, I think I did OK. Too bad it didn't have the cover....it opens up like a suitcase when its complete.

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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Wed Aug 08, 2018 9:48 pm
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Yes its a real find for that price.
It looks like the main stage has already been rebuilt with replacement transistors. Probably back in the day by the looks of it. If it runs balanced with them, that would be an improvement.
I see a burned resistor on the main amp board. Where the blue and black caps stand on end in the middle of the board. There are two 1000 ohm resistors with the same markings, Brown-Black-red. One is larger than the other. The smaller one is burnt. If you look closely between the brown and black stripe, the dark angular streak is an overheated resistance strip. The resistor should be replaced with a higher wattage version.
If is still intact, it may have drifted in value if it runs hot.
If its blown, it was probably taken down by a different component failure. That looks like a power supply voltage limiter to the caps on end. So if a component shorted, it would overheat that resistor and blow it.
It could also be a leftover from the original rebuild where the tech didn't feel it needed replacing.


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Post subject: Re: Old Traynor YVM-6 PA/Mixer
Posted: Thu Aug 09, 2018 1:19 am
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+1 Tim


ImageCapture d’écran 2018-08-09 à 04.16.21


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