Success! Traynor YCV20 reverb mod

[Rigormortis]

My Traynor YCV20WR had a very tinny reverb (Accutronics tank) with feedback. This problem is widely reported, and most players say they never turn the reverb up past 3 or4, pretty much writing off the reverb.

At the advice of some of the guys here, I got the schematics from Traynor's site and raised the value of a 100pF cap C35 in the recovery to 560pF and lowered the value of a shunt 200pF cap C59 to 100pF (used the old C35). I also swapped send and return leads to the tank itself, which eliminated feedback.

Now the reverb is not tinny, perhaps a bit chunky; and I can use the reverb in its entire range for the first time.

Here's the old thread:

Spring Reverb Options

I noticed now that amp hum increases gradually as I turn the reverb up, until at full tilt it's pretty loud. Since I could never do that before, I'm not sure whether it pre-existed. Is this normal for a spring reverb? Could it be that I shouldn't have re-used that old cap that I might have heated up too much getting it loose?

I'm also wondering about replacing some resistors in that circuit that Traynor replaced in later versions of this amp (past v 3.0). Those changes are recorded in the Traynor schematics on page 6 I think. Would these resistor values have anything to do with the hum?

[Rigormortis]

I got a reply from Yorkville/Traynor about the changes they had made to subsequent versions of the YCV20:

"The changes referred to are version 5.10 and deal only with reducing the noise floor in the reverb return amp. Aside from this revision, there have been no other changes to the circuit ( except for the addition of the headphone out ). This information is printed on the schematics as found on the web."

So I might be replacing the rest of the resistors mentioned.

Besides heping me with some of the questions in the above post, maybe you guys could help me with decoding the resistor values. I understand the ones that have the resistor values plainly labeled, but I don't know what 4R7 and 4K7 means. It's from this list of changes on page 9 of the service manual:


"Devices
M647 PENDING CHANGES13PC#6716 CHANGE R66&R63 TO 220K (4841), R58 TO 4R7
4866), R54&R53 TO 4K7 (4827), C35 TO 150N (5229), R88TO 100K (4838) [GT]"

I guess the numbers in parentheses are parts numbers?

[52 Bill]

The R and K represent ohms and thousand ohms. The position in the number represents a decimal point. So 4R7 is 4.7 ohm resistor and 4K7 is a 4.7K ohm resistor.

[Rigormortis]

Thanks, 52 Bill.

I wish I knew exactly what those resistors do in that circuit.

I'll need to go shopping for those. Our Radio Shack isn't very well stocked. Any suggestions for where I can easily buy such small quantities?

[olddawg]

Any electronics supply house. You can even do it on line. Don't use anything from Radio Shack. It's the cheapest Chinese crap.

[Rigormortis]

Except for the stuff in our Radio Shack--it was all made sometime during the Korean War, judging by the amount of dust on the packages. I know I'm the only person buying electronics in there, because my fingerprints are the only ones.

Can anyone recommend their favorite supplier?

[trance4ever]

Traynor Factory mod good!

I'll save everyone with one of the earlier Rev. Traynor YCV20 amps some trouble:

Just perform the mods indicated in the factory notice #11 Oct 6/04 ver 5.10 i.e. swap 6 resistors and one cap. Your Reverb will then sound reasonably good w/ a full usable range

I tried different values of C35 and C59 and found the stock values best. BTW my old C35 was 68 nanofarads. If you do what an earlier poster suggested and put the old C35 in C59's place you may really throw things out of whack. This is because C35's value is in nanofarads, not picofarads as the earlier post suggested. C59 should be 470pf

As for Traynor's reply that the factory mods "just lower the noise floor" - all I can say is what a load of bollocks. On my YCV20 the factory mods completely recalibrated the reverb pot so it acts like it should. Maybe Traynor didn't want hordes of early YCV20 owners emailing them for upgrades (assuming that the above statement really did come from Traynor).

In closing I can say that the amp is well built, very solid w/ excellent engineering (eg. great ground layout, regulated supplies, very quiet).

I'm thinking of doing a speaker upgrade but I'm suspicious of some claims that "getting rid of the crappy chinese speaker" will result in a stellar change in sound. Many of the most coveted vintage amps have speakers that would be considered "crappy" by todays engineering standards. Mind you, some of the smaller speaker manufacturers actually listen to their products during development (rather than building to a target market & price point). Maybe some of these speakers are better after all!

[Rigormortis]

Thanks for the contribution!

I'm pretty happy with the reverb with the mods I did, and will probably go back in and do exactly what you described.

I'm not sure you have those C35 and C59 values correct. The schematic says 100P and 470P, respectively; but I found the actual values of those originally my amp to be 100P and 200P, respectively. In any case, the new values of 560P and 100P work very well for my taste. Some might like a bit more treble than what I'm getting.

I quoted the Traynor spokesperson accurately.

I've found the greenback speaker to be just fine.

[trance4ever]

In the online YCV20 service manual

http://www.traynoramps.com/downloads...an/smycv20.pdf

See page 6; on the following schematic:

Product: YCV20 PCB#M647 Sheet 1 of 3
Date: Mon Sept 11, 2006 Rev: 7V00
Filename: M47-7V00sch.sch2002

At the bottom right of the page near the stylized Yorkville "Y" logo there is R64, R65 and C35.

C35 is listed as "150N 63V". "N" means nanofarads.

[Rigormortis]

Yep. That's the revision. Probably a good mod to do.

The original C34 on my schematic is a 100P, which as you know is pico.

I was being somewhat conservative with the change.

Traynor amps apparently had a quite a few revisions over the years, trying to fix that reverb problem.

[Rigormortis]

I changed C34, not C35. I had to go back and check, since it's been a while.

I think the cap in the treble bypass is the critical one needing replaced.

[Rigormortis]

I noticed now that amp hum increases gradually as I turn the reverb up, until at full tilt it's pretty loud. Since I could never do that before, I'm not sure whether it pre-existed. Is this normal for a spring reverb?

I just got a replacement reverb tank, and the hum is gone.

The problem was in a faulty reverb part that eventually failed entirely.