Need some guidance on an old Ampeg V3...

[LJGriggs]

I've had this amp for years (got it from a guy back in the mid 70's) and it still works great except for one thing... no reverb. Actually, the reverb hasn't worked in the 30+ years I've had it. I don't have a user manual for the amp, and it didn't come with the footswitch for the "effects" jack, so I don't know if that has something to do with the "no reverb" or if it is something else. (as you can tell, I don't know alot about this stuff ) I don't use the amp all that often because it's so dang heavy to tote around, but if it is something that is fairly easy (or cheap) to get repaired, I would like to get it working.

Any thoughts????

[Rob Mercure]

Hard to tell until you get in there. But if the circuit is indentical to the V4 - which is what my memory serves (not enough time to consult a schemo now) the reverb is driven from a 6CG7 capacitively coupled. There is a large plate resistor then the cap and then another power resistor from the cap-reverb in junction to ground. Common culprits on these amps are the plate resistor, the coupling cap, and the resistor to ground - all three commonly fail but I've never determined which component started the cascade failure - but I've cured the symtom of "no reverb" in these circuits at least a 1/2 dozen times over the years by replacing the same three components - and occasionally the 6CG7. If you've got enough experience to repair this yourself you will be readily able to identify the parts I've noted. If not then perhaps seek an experienced tech.

Rob

[mykey]

Any thoughts????[/QUOTE]

yes, take the reverb tank out and check for a
broken spring or a broken wire (inside tank), this happens
quite often on old Ampegs.

[Rob Mercure]

Mykey,

I really don't want you to think I'm picking on you - I'm not - but Ampegs used the same Hammond/Gibbs/Accutronics tanks that other NA manufacturers used and I've not experienced any more problems with these tanks than any other manufacturer. In fact I've replaced/rebuilt more Fenders but that's probably an artifact of working on more of them. If anything Ampeg protected their tanks better than most - my V4, and every one I've serviced, has a "reverb lock" that clamps down the tank when not in use - something the Fender, Gibson, et al, never seemed to incorporate.

While my suggested repair may easily be in error I will stand by my assertion that it is a common Ampeg problem unique to the capacitively coupled circuit - your not going to have to replace a driver tranny. And the Ampeg circuit is a tad more "forgiving" as the 6CG7 isn't driven as hard as the 12AT7 in a Fender type circuit.

But I welcome your sharing your experiences as they must be a bit different.

Rob

[J Martin]

I have seen a surprising number of the rev coupling caps fail. They seem to develop a lot of cracks in the first generation V4s. Maybe it lets moisture in? I never looked to see how deep they go. I replace them routinely now when refubishing those amps. Solen caps work well in that spot.

I keep new Fender and Ampeg tanks near my bench so I can check the reverb electronics before I go to the trouble of removing the tank. Saves time. This after a visual and voltage check, of course.

[Snapcase]

V3 has nothing in common with the rest of the V series amps. In fact it was the first (shortly lived) model of this series and was nothing else than a slight B25 evolution intended for guitar usage. As far as i know it never had a reverb. The few V3 pictures I have show a pretty simmilar head to to a B25. Just two channels, six knobs and no fx. Maybe you have a moded example or a rare prototype. Soon after the introduction of the V3, the same design team got the V4 circuit with reverb. Maybe your v3 is an obscure step in-between.

Here's the V3 schem.

http://www.drtube.com/schematics/ampeg/v3.gif

[LJGriggs]

As far as i know it never had a reverb. The few V3 pictures I have show a pretty simmilar head to to a B25. Just two channels, six knobs and no fx.

I think we may be talking about different Ampeg V3's. Mine is a Combo with a single 12" speaker, two channels, some sort of "phase" switch (don't know what that does) and a spring type reverb tank sitting in the bottom. I have seen some pictures of an Ampeg V3 head unit with separate speaker cabinet, but that isn't anything like my unit. Maybe I have one of the Japanese manufactured units that came along later... (I thought this thing had been around the house since back in the 70's, but I could be mistaken... age makes your memory fuzzy sometimes).

[mykey]

I think we may be talking about different Ampeg V3's. Mine is a Combo with a single 12" speaker, two channels, some sort of "phase" switch (don't know what that does) and a spring type reverb tank sitting in the bottom. I have seen some pictures of an Ampeg V3 head unit with separate speaker cabinet, but that isn't anything like my unit. Maybe I have one of the Japanese manufactured units that came along later... (I thought this thing had been around the house since back in the 70's, but I could be mistaken... age makes your memory fuzzy sometimes).

take out the reverb and inspect for broken spring and wires inside the tank.
the ampeg reverbs sometimes had a lock lever on the side, does your reverb have this and is it unlocked?

[gregstinson]

v3

The V3 you have I think is a late 70's early 80s model. I thought those were all Japanese so I don't know how you aquired it in the mid 70's...maybe time travel.. but either way.. I recently bought a New Jersey made V3 from around 70-72 and it has no reverb and is in head form.

[LJGriggs]

You could be right about the date on my V3

When I think back, my younger brother got this amp (and some other equipment) as a trade for some time in his recording studio. That would have been around '81 or '82. Back between 1975 and 1982 there was so much equipment from my bands and my brother's moving through my folk's basement it's hard to keep track of where it all came from. Anyway, it could probably stand to have a "tune-up". I'm sure at a minimum it wouldn't hurt to have some of the old tubes replaced. The old Celestion G12-75 speaker still sounds great...
I appreciate all the input on this amp!!!