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Ampeg V4 Reverb Issue

Serek_Basses

Serek_Basses

Mar 26, 2009
545
243
Chicago, IL
www.serekbasses.com
#1
I just got my hands on an early 70's V4, excellent condition, only issue is that the reverb isn't working. So today I open up the chassis and dismantle the reverb pan, lo, there are two small wires that have disconnected. I solder them up real quick and put it all back together.

Now, when I crank the reverb, I can hear the springs moving when I shake the reverb lock but still no reverb on the signal. I double check the input side of things, but there are no loose grounds anywhere and the RCA cable seems to be solid.

I then checked the 6cg7, but it is pretty much brand new and all aglow. Although, I have heard that when you tap this tube and the reverb is on you are supposed to hear it? I am not hearing it, but perhaps I have some misinformation.

What would be my next step? I am assuming that if I hear the springs, I don't need to replace the pan... where else to look?

Any advice is appreciated! Thanks
 
#5
Basslice said:
I can understand why you would want the amp to work as originally designed, but the V4 is a guitar amp. The V4-B is the bass amp sans reverb (same basic chassis and amp). Do you really want or need the reverb for your bass playing?
Click to expand...

I'm sure he just wants a functional amp - regardless of whether the reverb will be used or not. For what it's worth, when it's working the reverb on that amp isn't too shabby. The first few times I tried to use it on mine I forgot about the lock and was like ***? why is the reverb so quiet and lame, then I found out about the lock and shut it off. Sounded pretty good at that point haha. Good luck with your amp.
 
#6
Basslice said:
I can understand why you would want the amp to work as originally designed, but the V4 is a guitar amp. The V4-B is the bass amp sans reverb (same basic chassis and amp). Do you really want or need the reverb for your bass playing?
Click to expand...
if the guy wants reverb, he wouldn't be the first to use reverb on a bass.
 
#9
The RCA cable that returns the signal to the amp is just carrying a low level signal that needs to be amplified. If you unplug the cable from the tank and touch the Centre pin with your finger you should get a hum out of the amp most likely controlled by the reverb level control. If you get no hum the reverb recovery amp is faulty. Look also at the footswitch socket: some amps require a switch to be inserted for the reverb to work.
 
#11
zarigunn said:
maybe its couse its a guitar head, not like the v-4b.
Can the springs handle the vibrations... ?
Click to expand...

Not only do they handle it, but as coreyfyfe discovered, the V4 has a very sweet, natural sounding reverb.. Not overbearing or too effected sounding... Definitely a nice flavor to have at your disposal... I second all recommendations to get it to a seasoned tech and definitely think you're doing the right thing by bringing it in... Enjoy!!

-robert
 
#13
Hey hey! Zombifying this thread!

Reverb on mine doesn’t work neither. However, when I hit the head and the reverb pot is on (completely at max for testing), there’s a big « boiiiing » so I guess the reverb out is working.

Please note that last summer, I’ve replaced the two power amp in/out jacks with plastic Cliff jacks and did the same for the reverb foot switch jack.

The goal was to isolate the power amp in/out jacks from chassis. They work fine with Cliff jacks but not sure it was a good idea for the foot switch jack :thumbsdown:

So, I would guess I made a mistake when wiring the plastic jack and/or the jack automatically shunt the reverb circuit to ground.

When time permits, I will open the amp, put back the old jack and hope that’s the culprit…
 
#14
Patrice B said:
Hey hey! Zombifying this thread!

Reverb on mine doesn’t work neither. However, when I hit the head and the reverb pot is on (completely at max for testing), there’s a big « boiiiing » so I guess the reverb out is working.

Please note that last summer, I’ve replaced the two power amp in/out jacks with plastic Cliff jacks and did the same for the reverb foot switch jack.

The goal was to isolate the power amp in/out jacks from chassis. They work fine with Cliff jacks but not sure it was a good idea for the foot switch jack :thumbsdown:

So, I would guess I made a mistake when wiring the plastic jack and/or the jack automatically shunt the reverb circuit to ground.

When time permits, I will open the amp, put back the old jack and hope that’s the culprit…
Click to expand...

The foot switch sleeve needs to be grounded. If you did that with the cliff jack, it should be fine. Reverb pans have a way of burning out, the tiny wires are fragile. The new ones are even more so than the vintage ones. The wires are not soldered to the transformers, they push into a slot that cuts the wire sheathing. Sometimes they break.

Otherwise, it could be a problem in the send or receive amplifier stages.
 
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#15
beans-on-toast said:
The foot switch sleeve needs to be grounded. If you did that with the cliff jack, it should be fine. Reverb pans have a way of burning out, the tiny wires are fragile. The new ones are even more so than the vintage ones. The wires are not soldered to the transformers, they push into a slot that cuts the wire sheathing. Sometimes they break.

Otherwise, it could be a problem in the send or receive amplifier stages.
Click to expand...
Thanks @beans-on-toast , like said, it « boiiiings » when I tap on the head so I would guess the pan is ok.
Once in there, I will double check all components and wiring around the reverb circuit.

**Is it possible that the pan could be connected backward? Would it lead to a no reverb state? I’m not even sure I’ve tested it since the acquisition one year ago?


Anyway, I’ll keep you informed on my progress.

Thanks,

Patrice
 
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#16
Patrice B said:
Thanks @beans-on-toast , like said, it « boiiiings » when I tap on the head so I would guess the pan is ok.
Once in there, I will double check all components and wiring around the reverb circuit.

**Is it possible that the pan could be connected backward? Would it lead to a no reverb state? I’m not even sure I’ve tested it since the acquisition one year ago?


Anyway, I’ll keep you informed on my progress.

Thanks,

Patrice
Click to expand...

In and out are normally marked on the case. Connected backwards won’t work so you can try inverting them.

This is the same company as Antique Electronics.
Invalid Link Removed
 
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#19
Here is a pic before I replaced the jacks:

Is the beige wire tied to ground side of the jack or the reverse? There is also a black wire on the left, tied to a ground point, right to the preamp supply caps I would guess. I’m a little confused o_O

**Please disregard the messy wiring from yours truly around the main supply :)
upload_2021-11-2_22-7-52.jpeg
 
#20
Patrice B said:
Just to be sure to understand: the sleeve and the tip should be connected together (tip shorted to ground) to have reverb working? Or am I completely off?
Click to expand...

When the foot switch is closed, the tip and sleeve are connected and the reverb is off. The tip connects to the centre conductor from the pan. Closing the switch shorts the signal to ground.

[Invalid or Expired Link Removed]
 
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