Ampeg V2 midrange circuit

[Randall]

I have a V2 in for several repairs, and am down to the last one, the midrange control has no effect, at least almost all of the time. I did trace down a bad solder connection at the wiper leg. Once it was repaired, the control did work, so I thought it was done, but it only lasted a few seconds, and then it didn't work again. I am getting signal level to all three legs of the pot while the issue is present. Weird thing is sometimes when I power it down for a while, upon turning it on, the midrange works for a bit. Just now I powered it up and the control worked fine for several full range spins of the knob, until I changed the selector switch, then gone again. I don't remember if this was the case when it worked a coule times before for a brief moment.

Anyone have any insight? I'm really hoping it doesn't somehow involve the compactron 6K11 or the torroidal coil.

https://ampeg.com/support/files/Sche...20Version).pdf

[Justin Thomas]

Is that a 6K11 or a 6BK11? I think I may have a 6K11 in my stash that I'll probably never use, though I may not get to it for a while. But if you need one...

Is something maybe wonky in the switch, that's just masking itself? I have yet to meet one of those switches without some sort of quirk (granted, I've only ever met four of them)...

Justin

[The Dude]

Did you resolder the coil? I've had those solder joints crack in the past. Never had to replace one, though.

[Randall]

"Is something maybe wonky in the switch, that's just masking itself?"

I think you are correct, I cannot get any low ohmage readings on the top side if it at all, and only one reading that looks correct on the bottom. So, is it correct that the pot will not work if the switch is not working?

"Did you resolder the coil?"

I just did resolder that section of the board, it didn't make a difference, but I think I need to get that switch replaced first.

[Chuck H]

I worked over a V4 with the inductor mid circuit that had a hinky switch. As I recall there was some innard access through small openings in the case and I blew it out and sprayed some pot cleaner in there. It was working when it left my bench but I told the customer it might be short lived. Those switches weren't available when I did this work. I've read somewhere that Fliptops has them now. But that's just what I read. Fact check that. Replace the switch if you can. Justin is right that they all get funny.

[Randall]

I got it apart OK, cleaned it, retensioned the springs, which I think was the real problem. But, putting it back together, the chip boardback cracked. I was this close! Fliptops has them, $42 for NOS, and $25 for salvaged! Nutty prices, but supply and demand I suppose. Customer actually spring for new. That's gotta hurt.

[SoulFetish]

I got it apart OK, cleaned it, retensioned the springs, which I think was the real problem. But, putting it back together, the chip boardback cracked. I was this close! Fliptops has them, $42 for NOS, and $25 for salvaged! Nutty prices, but supply and demand I suppose. Customer actually spring for new. That's gotta hurt.

Randall, you're talking about the multi-leg chip in the tone stack, right? If you want I can dig around in our salvage and see if I can come up with one for you. I just had a V2 in a week and a half ago where half the legs were broken on both channels, but there was enough lead left to clip the others down and reconnect it. Anyway, if you're in a bind I can take a look. Is there much variation in these? Or are they all mostly identical?

[Randall]

Thanks SoulFetish, but we are talking about the 3 position slide switch above the front panel midrange pot. I ordered one from FlipTops.

[SoulFetish]

Thanks SoulFetish, but we are talking about the 3 position slide switch above the front panel midrange pot. I ordered one from FlipTops.

Oh, my bad, Randall. Glad you sorted it out though.