Special issue?

[The Rossness]

Everything was going well with my JF OD special. It's a great module, but I think mine has a problem. When I got home from work, I tried to play it and the problem started...

Somehow, no matter where I have the gain knob, the gain goes all the way up. I can have the knob turned completely off and it's still massive. It is also making a horrible buzzing/ringing/ vibrating sound. When I physically touch the faceplate and push in a little, the sound stops, but as soon as I take my finger off the faceplate, the sound starts again. I can't get any clean sound out of it- only massive gain and massive volume. The boost switch isn't working either.

I took the pointer knobs off the module and tried to get any kind of dust out, but that didn't work. I tried changing out the preamp tubes but that didn't work. I've tried it in different module slots and in a different amp, but nothing seems to be working. I'm not sure if its a bad pot or a resistor blew on the module or its a grounding issue, but something is wrong with my ODS.

I really like the mod too. It's frustrating. I get something... It works right for a week and then something goes wrong What's going on with my mod? What should I do?

I already sent rob an email, but I wanted to make sure I'm not doing something wrong or if there's an easy fix I haven't thought of. Any ideas? Has anyone ever had a similar issue?

 

[wesarvin]

Sounds like a similar problem I had with a different module. Is it seated correctly?

 

[The Rossness]

Sounds like a similar problem I had with a different module. Is it seated correctly?

I must have repositioned the module at least 40 times tonight. I've taken it in and out of my RM100 head put int into my RM100 combo, tried it in every slot and it's still the same issue. The PCB board isn't bent. I don't have the foggiest idea of why it is suddenly behaving this way.

 

[wesarvin]

Hmmmm...

Maybe Rob will chime in.

 

[rhequiem]

Replaced the module tubes and made sure the screws on the module were *all* the way in..?

 

[wesarvin]

Replaced the module tubes and made sure the screws on the module were *all* the way in..?

I agree. My issue with improper seating had very similar symptoms. It was with a Salvo module shipped from Australia. I think it got kicked by a kangaroo. The faceplate was ever so slightly bent, like a 95 degree angle instead of 90 to the pcb. A good swift "nudge" persuaded it to go in just right. No issues since.

 

[LunatiBSW]

Replaced the module tubes and made sure the screws on the module were *all* the way in..?

+1...tubes are always a great place to start, as well as the grounding screws

 

[The Rossness]

Replaced the module tubes and made sure the screws on the module were *all* the way in..?

Yea. I took the module out, undid the tube cage, replaced the tubes, put the cage back ontightened down the PCB to the base plate, took off the knobs, put on the knobs. screwed the set screws in all the way.

- If I adjust the module perfectly, It will sound like it is supposed to for about 45 seconds and then it goes back to crapping it's pants.

 

[iekobrid]

I currently have three modules acting that way, all modded.

When the sound cuts out altogether, if you switch channels does no sound come out of the other modules either?

 

[The Rossness]

I currently have three modules acting that way, all modded.

When the sound cuts out altogether, if you switch channels does no sound come out of the other modules either?

My other modules are fine. I have a Salv Angel B and a Salv C3 in my head and they're working perfectly.

It seems that bending the module's face plate has worked for now. I don't know if its a permanent fix though. It's too late to play, so I'll have to try it out some other time. I hope it doesn't require a major fix.

 

[iekobrid]

My other modules are fine. I have a Salv Angel B and a Salv C3 in my head and they're working perfectly.

I meant, does the one that's malfunctioning seem to affect the whole amp. With mine, if you're playing through perfectly fine modules in slots 1 and 2, sliding one of the wonky modules into slot 3 will actually cause all the sound from all the slots to cut out. Darnedest thing.

For months I thought there was a loose connection somewhere inside one of my amps because sound only came out if I hit it, Fonzie style. Eventually realized that one bad module was killing the sound from any other two modules I had in with it.

 

[Jaded Faith]

I sent you an email on this when I got a moment this morning. Sorry I wasn't able to write you back last night. I have a live sound obligation in the evenings all of this week and I am straight to bed by the time I get home from that.

Your symptoms are a textbook example of a broken gain pot and it needs to be replaced. I sent you an email about how to proceed.

Some troubleshooting info for the greater good of the community:

- If a pot works throughout it's range but you hear scratching, that is likely an issue of a dirty pot. It may be broken, but likely dirty.

- If the pot is stuck in one extreme of it's range or the other (full on or nothing) it's almost always broken.

This can happen in a number of ways to modules that most amps don't suffer from because as they are small, handled often by the face pate (which stresses the pots), ship often and can be dropped easily. Nearly every time I repair a pot it's the volume or gain pot and the side of the face where the broken pot resides is slightly bent. This can be from shipping, dropping the module or overzealous tightening of the thumbscrews particularly in amps where the modules do not seat perfectly flush.

If you have an issue like he describes where it's "all or nothing" it's almost never anything related to the slot, tubes, etc.

The tell-tale signs of a bad tube are obviously poor tone, but a sign I often see (only due to the high number of modules I encounter) is a less obvious one. A tube can be in the early stages of the way out and the only obvious symptom is decreased level but all pots working as they should. It can be a bad Optoisolator, but 95% of the time it's a tube failing. The best test is to roll tubes one at a time to isolate the bad one. I see this about once a month on donors folks send in.

Hope this helps and save you all some frustration and troubleshooting time.

- Rob

 

[bhuard75]

Pppfffttt.... I would have poured water on it while plugged in.

 

[The Rossness]

My other modules are fine. I have a Salv Angel B and a Salv C3 in my head and they're working perfectly.

I meant, does the one that's malfunctioning seem to affect the whole amp. With mine, if you're playing through perfectly fine modules in slots 1 and 2, sliding one of the wonky modules into slot 3 will actually cause all the sound from all the slots to cut out. Darnedest thing.

For months I thought there was a loose connection somewhere inside one of my amps because sound only came out if I hit it, Fonzie style. Eventually realized that one bad module was killing the sound from any other two modules I had in with it.

No, its only affects the OD special and the slot its i,. everything else works as advertised.

Jaded Faith- I'll get the OD Special module shipped out in a day or two.