Peavey Ultra 2-12 switching issue.

[catstrat]

This is the other amp that's giving me fits. The crunch channel will not activate. I need someone who can explain how the switching scheme actually works. I have the schematic but i'm not having much luck finding the problem. Thanks everyone.

[nashvillebill]

Ultra, or Ultra Plus? Can you post the schematic?

The Ultra Plus schematic shows 2 relays. K1 selects between Clean and Crunch/Ultra. K2 picks either Crunch or Ultra. So if it does switch between Clean and a "dirty" channel then K1 is OK. If it does not (stays permanently stuck on Clean) then K1 (or the footswitch that controls it, or some part of the connection) is bad. Must have the FS plugged in to select Clean, it grounds the relay coil, so if the relay is good and its stuck on Clean, then the relay coil is somehow staying grounded.

So if the Clean/dirty is working when you stomp the FS, but you cannot select between Ultra and Crunch, then the fault is either K2, or the FS, or the connection/circuitry in between. However, there is some circuitry around Q6 (ClampA) which doesn't make sense at first glance...but I don't think (at first glance) that a fault there would stop the Ultra/Crunch selection.

[Enzo]

Do you have and are you using the footswitch? Certain PV models will not go into crunch without the footswitch.

[J M Fahey]

I remember long ago (late 90's) I got an unexpected sales boost.

The Peavey importer had bought a ton of "grey import" stuff, which means legitimate stuff (not fakes or clones) , not bought from the original supplier but from somebody who has some stuff with unknown origin (not necessarily stolen), generally from Panama warehouses.

In this case it was a lot of 100 Peavey Ultra something rack preamps, 3 channels, clean/crunch/ultra , without the footswitches ... which could not be ordered from Peavey because they would ask how this guy needed 100 Ultra footswitches all at once while there was no record of any of those preamps ever being sold or shipped to Argentina.
In the the early 90's Rack setups were still popular for Guitar Players.

And problem is they defaulted, not to the crunch channel which might have been usable on its own , or clean, which would have required pedals for dirt, but to Ultra, which was a killer, ferocious high gain sound ... unusable on its own unless the player was a crazy 24/7 shredder who never stopped soloing.

They sold a couple anyway, but the rest was gathering thick piles of dust.

We reached an agreement: they sold them at a very attractive price, I offered a 100W 2x12" powered cabinet and included the custom footswitch as a bonus, offered the whole pack together.

Sold the whole stock in about a year.

[tedmich]

I remember long ago (late 90's) I got an unexpected sales boost.

The Peavey importer had bought a ton of "grey import" stuff, which means legitimate stuff (not fakes or clones) , not bought from the original supplier but from somebody who has some stuff with unknown origin (not necessarily stolen), generally from Panama warehouses.

In this case it was a lot of 100 Peavey Ultra something rack preamps, 3 channels, clean/crunch/ultra , without the footswitches ...

Perhaps it was a load of these?

Rockmasters with "Ultra Gain"

[catstrat]

ultra 2-12

It is the Peavey Ultra and not the Ultra plus. I noticed it has the footswitch for the ultra plus. Wrong footswitch i'll bet. The Ultra has 5 relays in it. My computer is showing it's behind so i'm not able to post much of anything right now. I'll keep working on it though. Can all the channels on this amp be switched on by the panel switches or does it have to have the footswitch? I remember the Peavey Triumphs had to have the footswitch or the amp would default to the ultra channel with out it. But it didn't have panel switches either.

[g1]

According to the manual, crunch channel must be activated by the footswitch. The crunch gain switch only changes the gain of the crunch channel once you have selected it via footswitch.
Channel select switch selects between clean or ultra channels.

http://assets.peavey.com/literature/...tra_manual.pdf

[Jazz P Bass]

And the Ultra & Crunch channels are not that much different.

They simply use a different taper on each gain pot.

Ultra 120 Crunch_Ultra pots.pdf

[Enzo]

Different value pot, 50k versus 1 meg. That makes a different voltage divider with the rest of the circuit, and so the crunch works with a much lower signal level, just from that change. I had a guy ask once, and he replaced the 1 meg with a second 50k, so he essentially had two crunch channels and no ultra, he could set them different for tone.