Peavey Ultra-Channel Switching mod?

[Trick]

Hi, I have a Peavey Ultra Tube combo that I absolutely love the sound of, but is not versatile in one area.

When switching between channels there is a 'drop out.' Anyone know how to make it seamless. Basically like any other amp. I would start using this as my main gig amp again if this could be remedied.

There are a few other problems, but I think i might take them to get checked out. I have a bad hum running through the amp. Don't know if this is the same problem like I had years ago and it just worsened. The hum which I think was more of a buzz at the time would come on intermittently, but when I flipped the ground switch in the back it would cease. Now when I flip it, the hum stays. Master volume knob is broken because it has no friction like the other knobs and is scratchy. I'll be thrilled if I can start using this amp full time.

Thanks for the help.
Sean

[tedmich]

hmmm my ultra has no such "drop out" did it do this back when the ground switch worked on the hum? was the vol. knob damaged recently?

You'll need the vol pot replaced and the exact part is available from PV for a few $. Unless you are experienced working on tube amps/ PCBs I'd have a decent tech do it (the voltages, even unplugged can kill you!). Once inside the tech can re-tension all the molex/connectors inside and maybe the footswitch pin/socket too. Also have them check the ground connection and you check that the ground you are using is good.

The channel switching on this (and most other PV) amp uses a transistor to remove noise etc. and its possible the transistor needs replacement.

Do you have the stock footswitch? The schematic (free) and all parts (cheap) are available from PV.

[dmartn149]

My Ultra didn't do that either. I bet the hum is related to the broken master volume. Mine was really quiet, even with LOTS of gain. That was an amp that seemd to be able to make any guitar sound great. But with 4-10s it was just too heavy.

[tedmich]

My Ultra didn't do that either. I bet the hum is related to the broken master volume. Mine was really quiet, even with LOTS of gain. That was an amp that seemd to be able to make any guitar sound great. But with 4-10s it was just too heavy.

yeah I figure my 212 weighs ~1.5lbs/watt of output ....ugh! Maybe a head conversion is in order, as I am currently playing it through a 2 x 5.5" Seas kevlar drivers in a 6x6x20 box...

[Trick]

thanks for the replies...Yeah, it's definitely the heaviest 112 I've owned, so I could only imagine the weight of a 410 or 212.

The hum did seem to start since the master volume 'cracked.' A few years ago I did have a buzz running through the amp and I remember playing with the reverb molex connector, but don't remember what I did. I might of replaced the barrels inside the connector.

The drop out that I am talking about seems like the amp was made this way, so let me better explain it. If I am playing a constant rhythm and switched to the ultra or crunch channel the sound drops out for about a second. This is troublesome if I want to switch effect on a downbeat or whatever (does not feel natural). So you guys don't have this issue? I am using the footswitch for this. If I push channel button on amp, there is no drop out. I never had the opportunity to try another ultra tube. If this is not a stock issue, than what could be causing this? Does it sound like a transistor problem? I try to be safe working inside of amps, just am not that knowledgeable reading a schematic. I have no problem soldering a new component onto a pcb. So, if you have any suggestions that would be great.

maybe I can upload a clip so you can hear it. can I upload it here or do i need to use a separate server.

thanks again.

[Trick]

Hi, I've uploaded an audio clip of the channel switching. And I uploaded an image of the recording so you can see the channel switching. The part that is highlighted in white, was using the same rhythm and you can visually see the drop out. Maybe that is the way this amp is, but it doesn't feel natural when I switch the channel. I am so used to the fender deville, it sounds like it adds the overdrive on top of the clean, so maybe that's how that circuit works. Can I make the Peavey react this way, with no dropout. The drop out is about: 58 milli seconds.

Thanks for the help.

[Trick]

hum

I recorded the hum. The hum started happening about 10 minutes into the amp being on. It's on the master side the individual channel volumes have no effect only the master.

Well, as I was taking out the master volume, half of one of the solder pads came off the pcb. I noticed the center post of the pot was folded over and had trouble getting it loose. In doing so, I took half of the solder pad with it. Is there a way to replace the pad, or did I ruin the whole thing? Hope it is an easy fix. thanks

[Trick]

damaged solder pad

a picture of the damaged solder pad

[J M Fahey]

Hi Trick.
It doesn't look that bad, you have two beefy pads supporting your pot plus half the center one.
Anyway, you can repair it by soldering a bent piece of wire, similar to a hairpin, with legs, say, about 3/8" and the "ring" in one end somewhat larger than the board hole.
That green paint (solder mask) you see over the copper will have to be scratched off first,
Do it carefully, you don't want to scratch off the very thin copper itself.
I've been listening to your switching mute delay.
It's not 1 second long , more like 1/4 of a second, but definitely heard.
Its duration is controlled by the "time constant" provided by a 1M resistor and a .1uF to .22uF capacitor, which is discharged by a MAC97 Triac everytime you switch any footswitch on or off.
I don't refer to specific part numbers because it depends on your particular model, I've checked a Rockmaster preamp and an Ultra 60, the basic idea is the same.
I'd suggest you replace that capacitor with another half the capacity, that means .1->.047uF or .22 to .1uF.
This should cut your mute time in half.
Maximum mod suggested: 1/4 the original value.
Don't overdo it or you will start to hear the clicks.
Peavey engineers are intelligent and very practical guys and must have had a good reason to use that.
Post your results.
Good luck and work carefully.

[Trick]

wow, thanks for all that info Mr. Fahey...I was working on a practice pcb and was using a razor blade to scrape the mask off. I'm afraid that I may damage the other one using a blade, is there another tool you would suggest that would not mar it up so much. I felt like I was cutting into the copper like you mentioned. Also, I'm not removing the existing pad, right? I am removing the mask below the half pad and attaching the wire to this?

thanks again

[tedmich]

wow, thanks for all that info Mr. Fahey...I was working on a practice pcb and was using a razor blade to scrape the mask off. I'm afraid that I may damage the other one using a blade, is there another tool you would suggest that would not mar it up so much. I felt like I was cutting into the copper like you mentioned. Also, I'm not removing the existing pad, right? I am removing the mask below the half pad and attaching the wire to this?

thanks again

a little piece of silicon carbide wet/dry sandpaper, maybe 320-400 grit used carefully does a good job removing the mask, I check for continuity with a DMM probe to see if I'm through. Coloring it with a sharpie also lets you see when you are through the mask. I tin it up quick before it oxidizes, then re-solder at my leisure.

Others may use a solvent (xylene, lacquer thinner, methylene chloride?)

[J M Fahey]

Yes, the fine sandpaper is also a good option.
The key here is do not be heavyhanded.
Practice on any old board, good idea.
Being an expensive and very high quality epoxy, solder masks resist most solvents.
Acetone might soften it a little, but you will do well with mechanical scraping.
Also a circular brass wire mini brush on a Dremel will do, but for a single job, manual removal is more than good enough.
A steel wire brush or an abrasive mounted stone will be too much.

[Trick]

thanks...I will be giving the sandpaper a go. Is there a way to insulate the wire that I'm adding or coat the top with something. Or Is that unnecessary?

[J M Fahey]

If you get cheap one of those little "surgical knives" used by artisans or would-be sculptors to carve wood, will do OK.
The trick there is that the blade is curved and you can scratch gently without going deep.
Or just try the abrasive paper.
After you solder that copper wire loop you won't need any special covering, it's the same as any soldered pad there, only larger.
Solder masks are mainly used to avoid needlessly tinning (expensive) and leading (toxic/anti-ecologic) any more than what's strictly necessary.
Boards up to the 70's looked silver everywhere, then green , GK's blue, and now many look red or even black.
They've got "hot" and "evil" sound respectively.
Don't believe me? Just look inside your Bugera

[Enzo]

What you need is one of these. I have been using these fiberglass erasers now for about 35 years. The fiberglass is stiff and abrasive, but softer than the metal. it will take conformal coatings off with ease leaving shiny clean copper. it will clean up oxidized copper for better solder wetting. I buff up edge card connector traces with it.

Just don;t run your finger over the end of the brush. You''l get little glass fibers in your skin.

They also make similar brushes in brass and fine fiber. But I prefer the coarse fiber as shown.

[AA0020] E111/C Metal Body Coarse FybRglass® Eraser