Ampeg V4-B will not turn on

PunkJazzHeavy · #1 08-07-2011, 03:46 PM

My amp is not turning on. The jewel light isn't lighting up and the fuse is not blown. I researched it and it said it could be a could be slew of things. I replaced the fuse, and it still worked fine. Now I am thinking it is possibly my rectifier tube. There is a black spot on it... a picture is attached. If that is not what it is, then I am thinking that something needs to be resoldered on the inside.. your help would be greatly appreciated thx!

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anonymous02282011 · #2 08-07-2011, 03:49 PM

Did you try buying it flowers?

Ok, just kidding : )

It sounds like something (a tube? a resistor?) burned out. Time for trip to the tech.

Where are you located? Maybe some folks can make recommendations

PunkJazzHeavy · #3 08-07-2011, 03:56 PM

I live in Nashville.. got a great tech here, Marc Ferguson.. I just rather save the money! (If I can diagnose the problem on here!)

**Matt Lake** · #4 08-07-2011, 04:01 PM

Could the power switch have gone bad ? I'm not sure how it's wired, but the power light is just a light bulb. Try SAFELY jumping the wire connections at the power switch.

RickenBoogie · #5 08-07-2011, 04:27 PM

Saving money is great, but unless you are equipped with all the diagnostic gear, you're much better off taking it to the guy that does.

Bassics101 · #6 08-07-2011, 04:32 PM

I'd highly recommend not going in if you are not qualified. See your tech. Could be very simple, but why take a chance on such a nice head.

BassmanPaul · #7 08-07-2011, 04:35 PM

Quote:

Originally Posted by PunkJazzHeavy

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That, Sir, is not a rectifier tube - it's a pre-amp tube. The best suggestion I can make, given your obvious lack of tube knowledge, is to take the amp to a tube tech and get it repaired. Anything else is risking both your amp AND your well being!

nashvillebill · #8 08-07-2011, 04:56 PM

The Ampeg V4B does not have a rectifier tube, it is solid state rectification. The tube shown, as BassmanPaul wrote, is indeed a preamp tube, and the black stuff on the side is the getter flash, which is normal.

I live up in Gallatin, I'm familiar with the V4, and if you want I can take a look at it.

KramerBassFan · #9 08-07-2011, 06:02 PM

The V4B does not have a Rectifier tube.

You might have a super dirty switch, or a bad power cord.

That looks like a 6K11 to me (the reverb driver that Ampeg used in their V4 amps, which the v4B shouldn't have) - are you sure its a V4B?

anderbass · #10 08-07-2011, 08:03 PM

PunkJazzHeavy, If you want to try something yourself:

Go to radio shack and buy a can of Deoxit electrical cleaner. Then lay the unplugged amp on its back and slowly spray the cleaner around the base of the power switch toggle-lever so the cleaner gradually works its way inside, then work the switch on and off like 30 times to hopefully clean the contacts and get it working again.

**B-string** · #11 08-07-2011, 08:13 PM

Quote:

Originally Posted by KramerBassFan

The V4B does not have a Rectifier tube.

You might have a super dirty switch, or a bad power cord.

That looks like a 6K11 to me (the reverb driver that Ampeg used in their V4 amps, which the v4B shouldn't have) - are you sure its a V4B?

6K11 (triple triode if IIRC) was used in the tone circuit of the V4B.

They also seem to last forever in that application.

PunkJazzHeavy · #12 08-07-2011, 08:16 PM

Is it safe for me to take the amp out of the chassis to simply look inside and see if anything needs to be resoldered?

@KramerBassFan, I am positive it is a V4-B, it says it is on the front of the amp.

@anderbass, thanks I willl try that

nashvillebill · #13 08-07-2011, 08:53 PM

It's only safe if you are competent at working around electronic components that can still be storing 545 volts DC, at currrent levels that can cause heart defribrillation.

Even with the amp turned off, the power supply caps can still be charged. And IIRC there is one immediately within finger's reach of the power switch.

nysbob · #14 08-07-2011, 09:07 PM

I've got one that won't turn OFF. I'm sure it's the switch, I can smell it.

I'm taking mine in - my soldering skills are lame...plus it needs a grounded AC cord anyway.

PunkJazzHeavy · #15 08-07-2011, 09:17 PM

Also, could you guys give me a best case/ worst case scenario?

Thx so much for your help already, I am learning alot and I really appreciate it.

KramerBassFan · #16 08-07-2011, 09:44 PM

Well i learned something new - i thought it was the reverb driver.

**B-string** · #17 08-07-2011, 09:47 PM

Best case bad power cord or power switch. Worst case open primary in the power transformer.

**B-string** · #18 08-07-2011, 09:49 PM

Quote:

Originally Posted by KramerBassFan

Well i learned something new - i thought it was the reverb driver.

Ya ain't dead yet if you can learn something every day

BTW a 6CG7 was the reverb driver in the V4

PunkJazzHeavy · #19 08-07-2011, 09:55 PM

Quote:

Originally Posted by B-string

Best case bad power cord or power switch. Worst case open primary in the power transformer.

What does it mean to have an "open primary"? Also, would that mean I would have to get a new transformer?

Thanks for your help

**B-string** · #20 08-07-2011, 10:03 PM

Quote:

Originally Posted by PunkJazzHeavy

What does it mean to have an "open primary"? Also, would that mean I would have to get a new transformer?

Thanks for your help

Open primary would mean a new power transformer, around $200.00 plus labor costs. The amp is still worth it BTW.