Ampeg SVT-VR problem

[sa1126]

I'm having issues with my SVT-VR. When you turn the amp off of stand by there is some latency (a few seconds) before it turns on. The volume pot gets really scratchy once the amp is on.

Does this meet any of the tell tale signs of recurring issues with this amp? I know this amp seems to have issues- anyone have any ideas?

Thanks

 

[TrooperFarva]

How long do you have the amp on before you try to take it off of standby?

For the scratchy pot, try some deoxit.

 

[sa1126]

It usually warms up for 30 seconds to a minute. Would anything be wrong that would be causing the pot to make noise?

 

[Tony Gray]

I don't think we can say anything bad about Ampeg, they've become a sacred cow.

Try customer service, while they still have someone to answer the phone.

 

[megadan]

The latency is probably normal.
The scratchy pot can be fixed with deoxit as suggested (all though it shouldn't have to be for what we pay for VR's)

 

[B-string]

Any "pot" can be subject to noise issues no matter how much you pay for an amp or replacement pot.
I personally don't understand why there should be a delay coming off of standby with the amp warmed up (30 seconds should be enough). Maybe a defective tube causing it, that tube could still last a long time or could fail when you least want it to. Go for a checkup.

 

[JimmyM]

I don't think we can say anything bad about Ampeg, they've become a sacred cow.

LOUD has already whacked that cow in the head with a sledgehammer and gutted it. Only thing is they threw out the steaks and kept the intestines and gross parts that only my dad will eat.

 

[B-string]

LOUD has already whacked that cow in the head with a sledgehammer and gutted it. Only thing is they threw out the steaks and kept the intestines and gross parts that only my dad will eat.

LOL

 

[anderbass]

sa1126,
I was wondering if your having the delayed-standby issue in serveral diferent rooms/stages or possibly just in 1 room?
Have you measured the 110volt wall socket voltage? (there's some fairly inexpensive testers available) I was thinking you might be just dealing with a borderline low 110-voltage issue thats delaying your amps standby circuitry a bit.

This thread covers the low voltage issue I'm referring too:
http://www.talkbass.com/forum/showthread.php?t=446053

If you decide to CARFULLY test your buildings voltage, I'd do the test with your amp plugged in so the circuit will be under a load. With the amp on and in standby, take a voltage reading at the other unused receptacle of the very same wall outlet, and then see if your voltage drops below 112 volts as you switch the amp out of standby.

If this is your problem, you should probably call an electrician, but If your voltage readings are borderline (around 112 volts) and you have a bunch of other "things" running off that same circuit breaker, you might just need to use an outlet from another rooms circuit for your VR. (possibly w/a high quality 12 gauge extention cord)

 

[Jerrold Tiers]

It would be 100% NORMAL to have somewhere between 4 and maybe 8 seconds before the amp sounds right.

There will be 3 or 4 seconds before you even get good power out.

This is because there is NO high voltage applied in standby. When you hit the standby switch to "off" (ready for use) then high voltage is applied. The switch actually applies mains power to the high voltage transformer.

Ok, so now the +660V comes on, but there are dropping resistors and more power supply capacitors in preamp and screen supply, etc, that have to charge up. That takes a few seconds. I think the "time constant" for the preamp is around 4 seconds.

 

[alfredpunkjazz]

Mine does the same thing, but it always works, BTW, is a MIA one.

There was just this one place where it wouldnt work, but the place was a mess, I was not surprised at all. Seems like they have a safe designed circuit in there... I can't remember.

 

[B-string]

My 1973 V4-B is up and completely ready less than 2 seconds after coming off standy.

 

[Jerrold Tiers]

My 1973 V4-B is up and completely ready less than 2 seconds after coming off standy.

The time will be specific to the unit, power supply details, and voltages...... each type will be different, so you can't really compare them directly.

2 seconds is fast enough that you might have some capacitors getting weak....... The faster it comes up, the smaller the actual capacitor values are.... comparing "identical" units. So a fast turn-on can indicate capacitors that are losing "capacity".... (But then, I haven't looked up that unit to get an idea of what to expect, I'm just estimating)

 

[B-string]

Caps are good, the stanby switch is handled differently.

 

[Jerrold Tiers]

Yes, it is.....

I looked it up, and while it is different, 2 sec still sounds a little fast for what I'd expect.

But, if it doesn't hum or tick, or "motorboat", you're good, for now anyhow.