standby switch

[troonbop]

Hi folks; I have a Traynor YCV40, 2002 roughly. The standby switch stopped working, it still switches off and on, but nothing happens, it doesn't power down. Amp still works.
Any suggestions?

[Ty_Bower]

The switch's contacts could have welded together. There's inductance in the high voltage circuit. If the standby switch is on the DC side, you've got the output transformers themselves plus any power supply filter chokes. If standby is on the AC center tap, you've got inductance from the PT itself. Trying to interrupt the circuit is going to result in high voltage spikes across the switch and a good chance of arcing.

Take the standby switch out of the circuit, and check it with your ohmmeter.

[mesherm]

Do the ON and STANDBY LEDs light up normally as before? Half of the DPDT switch works the LEDS and the other half lifts the ground to the output tubes so that when on STANDBY the output tubes are ungrounded.
Obviously the tubes have found a path to ground somewhere.

http://www.traynoramps.com/downloads/servman/smycv40.pdf

[troonbop]

Thanks for the replies. Yes, the lights do come on normally. I guess the best bet is to get at the swtich and look at it; i'm a little new to this, so it might be a bit of a job because it doesn't seem very accessible.

[Cygnus X1]

Don't forget to discharge your caps.
Safety first!

[dunlapd@vt.edu]

I have the same issue with a YCV40 standby.
I followed ALL of the Service Manual updates to no avail.
The switch appears to be working fine (not welded as suggested by one post).

I can't figure it out. The standby seems to work through the ground on the grid (pin 2) of the first preamp tube 12AX7. right? I can't follow it.

The last update in the Service Manual runs a jumper from the switch to a terminal that goes somewhere in the reverb circuit I think. Again, I get lost.

THAT update gets the standby to function, but with a bad hum when on standby. That doesn't seem right. Why should anything be output when on standby??

Nevertheless, the light seems to be working, both sides of the switch seems to be working fine. So I'm left with no standby, or one that produces a bad hum.

I'm lost.
thanks for any advice and help!!!

[soundbrigade]

Be careful with StandBy-switches. If the tubes are allowed to stand with heater voltage on but anode voltage off they will suffer from cathode poisening.

[dunlapd@vt.edu]

well, I'm only doing what the Traynor service bulletin says.
And I assume, if there's hum, then there's some current flow, so the tubes should be ok. I might be totally off here.

I wish I could figure out a work-around, but I'm guessing they tried to engineer a cheap and nifty standby circuit that didn't stand up. The switch won't withstand the vintage method, even if I could figure that out. I just can't figure out what happened to make it stop working.

BTW, this came in with dead tube and blown fuse. Replaced those and got it working fine. Now the standby doesn't operate. Maybe I'm missing another faulty component.

I'm lost.
Giving up, unless there are other suggestions.
thanks !!

[TomMcNally]

I looked at the manual and updates ... a couple of things ...

1) it's not really "standby" that turns off the high voltage,
it just mutes the audio ... you can do the same thing
by turning the volume down

2) the updates are specific to models, you can't do all
of them - only the one for your specific amp

[dunlapd@vt.edu]

yep, I did the more complicated mod intended for the version I have (it's the earliest version). It didn't work. I got all of the components directly from Yorkville (Traynor). They were cool. They sent all of the parts to me free. Didn't even charge shipping !

But to no avail.
Oh well.

Thanks very much for the help here !!!!