Traynor YCV40 standby problem

[Prairie Dawg]

Anyone here ever work on one of these where the standby is inoperative? It seems like there are a number of fixes from Yorkville/Traynor depending on which circuit board/serial number you have, all of which require some surgery. I'm inclined to tell the owner to just turn the volume down and not worry so much.

Comments? Horror stories?

Thanks.

[g1]

From what I recall, when they first came out we had to do the mods. on them when ever they came in for service. Seems to me it wasn't as much work as it looks from the bulletins. I asked why they didn't just use a normal switch like everybody else, rather than an electronic standby circuit. Apparently the cost of the hardware switch was way more than the power Fet and other components.
I would think they would probably send out the parts no charge if it never got the mod. Otherwise, you could always add a standard type hardware switch.
If you just go without standby I would think you should really get in there to bypass the defective parts anyways, so why not do the mod?
Contact Guy at Yorkville service, he's very helpful.

[Prairie Dawg]

I got an answer back from Yorkville and they said parts are available but turning down the volume is fine as well if the out of warranty customer doesn't want to pay for the work. It doesn't seem like the more normal B+ lift type standby switch either.

[g1]

Definitely not standard B+ lift standby. I've since read that there were CSA issues (Canadian safety) with having a high voltage switch, so they went with a low voltage/current switch toggling the electronic circuit to disengage B+. But if that were the case, I don't think they would be able to sell new imported amps that have high voltage standby switches in Canada. So I'm inclined to believe what I was told about it being a attempt to save money (that really backfired).
The new version is really a mute switch rather than standby. It uses one side of the switch to toggle the run/standby lights, the other side of the switch grounds the signal between FX loop and power amp. Looks like the power FET is now only for regulation.
Earlier circuits used opto's and the FET to kill or reduce the high voltage, the mods required depend on the circuit version. They can fail so that the amp is stuck in standby, stuck in run, or somewhere between with reduced B+ and poor sound.
Sounds like yours is stuck in run. It could stay that way forever, but could also change to one of the other failure modes at any time.

[Gtr_tech]

They shoulda used a relay then if they didn't want plate voltage on a front panel switch. Just for reliability....

[Prairie Dawg]

To tell you the truth, not being familiar with the circuit I figured I'd find a bad relay or something. I've got a message into Yorkville in the US about getting the parts kit, it looks simple enough to do. This problem seems to effect the YCV40 only, my manuals for the YCV50 and YCV80 do not seem to have much in the way of reference to this issue. Is Guy at Yorkville south or north of the border?

UPDATE: I got a message back from Yorkville product support and here's what it says:

In this case, the mods, or lack of them, have no bearing on the failure here. This is a classic case of a shorted Q8 FET, just replace Q8 along with D13 and U3 and make CERTAIN that you have good power tubes before you restart the system or you will blow the Fet all over again.

The mod described is applicable to the unit you have, but it is not in any way necessary to effect a repair of this amp. This addition was an attempt to provide short circuit protection to Q8 when a tube shorts out and dumps everything through the FET and kills it. The second mod is nothing but a signal mute ( to the splitter ) which coincides with placing the amp in standby mode.

Looks like the resolution is a lot less complicated than I thought.....time for a stroll over to Mouser for parts. Things are looking up.

[g1]

Just noticed that in the new version the standby also lifts the cathodes of the output tubes, so it does more than just mute the signal to the phase splitter. Not sure if this was done in the older versions.
Guy is up north at the factory, but it sounds like you are getting good info. support wise. Best of luck and let us know the outcome.

[Prairie Dawg]

Got my parts ordered. It's a good thing to physically check the parts in question, on this amp Q3 is a 4N35 optocoupler rather than the more typical NE5532N dual op amp.

But yes. The support's good, far above and beyond a lot of bargain basement amps from overseas people complain about all the time. That's another reason to buy their gear.

[Prairie Dawg]

Got my parts ordered. It's a good thing to physically check the parts in question, on this amp Q3 is a 4N35 optocoupler rather than the more typical NE5532N dual op amp.

But yes. The support's good, far above and beyond a lot of bargain basement amps from overseas people complain about all the time. That's another reason to buy their gear.

Just as an update, I installed three parts per Yorkville Service, the IRF 830 FET (Q8), the 10v Zener diode (D13) and the 4N35M integrated circuit (U3) and the standby switch now works as advertised. I didn't like the RoHS lead free solder but this is the brave new world we live in. Make sure and use a little heat sink compound on the IRF 830.

[beezerboy]

Hi guys.... I'm doing this repair now. there are also a couple mods the factory manuals says to do that haven't been done. one is a protection circuit for the mosfet that explodes. they call out a transistor(?) MPSA 13... thats a Traynor number.... has anybody done this mod & know what that part really is? I'm putting together a Mouser order & would like to only ship one pile
thanks, Tom in AK

[52 Bill]

...they call out a transistor(?) MPSA 13... thats a Traynor number....

Are you saying this is a Traynor part number? MPS-A13 is a generic number for a transistor and should be available from Mouser.

[beezerboy]

oop yes it is.... sorry.... had it in my head it was a proprietary. I found it at the mouse & it's on the way.. I was just coming back to wipe this post before I got caught bein a dumazz ha ha


turns out you have to type in the right numbers (letters), AND they have to be in the right order

[mokomon]

Just changed all usual parts for no high voltage and amp still has no B+ past Q8. I fired amp up without power tubes , would that cause Q8 to go again ?

[g1]

Please post schematic version for your particular revision of amp.

[mokomon]

schematic_ycv40_M581-6.20.pdf I believe this is the correct schematic. I am not getting B+ past Q8 , only about45v