Noisy pots

[bsco]

The pots I had were 1M audio taper....Alpha.....just so that you will know....
Cheers
P.S> I'll take Enzo's advice and give them a call anyway.......I'll post the outcome here.......

I called the company and explained to them what had happened.....They are going to send me out the pots again and they just received a new shipment of these....so they are going to take 6 from the lot and ship them out tomorrow in the mail......I asked them if they wanted the old ones back and they said it wasn't worth the hassle or the shipping costs to return them.....so there you have it......they looked after the issue.......and it is much appreciated.....
Cheers,
Bernie

[Chuck H]

You never get anything if you don't ask Not that I'm that type. I'm actually distinctly not. But consider that if you asked a hundred people for ten bucks with no better reason than "I have spent too much of my own money and now I would like to have some of yours." You are almost sure to get more money than a guy who isn't asking. So, There you go. I've seen people lose and or miss out by not following this rule and I've seen others make a tidy but unscrupulous living by exploiting it. Asking a company to pick up their end when bad product was vended seems reasonable to me.

[Enzo]

I always give a vendor a chance to make things right when a problem occurs. MOST companies want you to be satisfied. It isn't worth losing a customer for $5 of parts.

[DrGonz78]

Not to mention it helps inform the vendor about quality control issues. The company then has an opportunity to be able to perform quality checks on these specific items before more customers are let down.

[bsco]

Not to mention it helps inform the vendor about quality control issues. The company then has an opportunity to be able to perform quality checks on these specific items before more customers are let down.

I take it the pots you ordered were good??? The company was pretty good about it.....I must say...

[DrGonz78]

I will breadboard up something tomorrow and just go through all the pots to make sure. I bought a whole bunch of them so the task seems a bit daunting. Will post back my findings too.

[bsco]

[QUOTE=DrGonz78;391261]I will breadboard up something tomorrow and just go through all the pots to make sure. I bought a whole bunch of them so the task seems a bit daunting. Will post back my findings here......

It could be that I ended up with some bad pots .......and the rest of the pots that they had are ok........but still strange that all six were bad..... anyway, that's it..your's might be fine......
Cheers

[DrGonz78]

Well the good news is that all 6 of the 1M pots that I tested are good. No scratchiness or anything like that. That is strange that all the pots you got had the same defect. Thanks BSCO for the heads up just in case I had the same problem.

[bsco]

While we are on the subject of noisy pots....If you have dc or if you suspect that there is dc leaking into a pot, at what level does it cause problems???is it a couple of mV or a couple of uV......or maybe there should be absolutely no DC leakage whatsoever....I am just being curious here.......
Cheers

[Chuck H]

While we are on the subject of noisy pots....If you have dc or if you suspect that there is dc leaking into a pot, at what level does it cause problems???is it a couple of mV or a couple of uV......or maybe there should be absolutely no DC leakage whatsoever....I am just being curious here.......
Cheers

Great question. What I've always done is just fix what's problematic. At the low levels of DC usually read on pots, some is meter default, some is just anomalous register from weirdo guitar amp operation. If you get more than a volt (over meter default) then there may be something that needs looking into. But some amps just do this because of their design! It's hard to know IME. Like I said, I fix what sounds bad. If I ever read something over a volt of DC where it wouldn't typically be I try to analyze the circuit and it's operation to see if that may be the cause. If there's obvious DC, like four, five or ten volts, I look for a repair.

[bsco]

Great question. What I've always done is just fix what's problematic. At the low levels of DC usually read on pots, some is meter default, some is just anomalous register from weirdo guitar amp operation. If you get more than a volt (over meter default) then there may be something that needs looking into. But some amps just do this because of their design! It's hard to know IME. Like I said, I fix what sounds bad. If I ever read something over a volt of DC where it wouldn't typically be I try to analyze the circuit and it's operation to see if that may be the cause. If there's obvious DC, like four, five or ten volts, I look for a repair.

The reason why I asked is that I have a problem with a JVM410H...all 4 gain pots are very scratchy when turned..and it is not the type of noise associated with a dirty pot.......it sounds like dc.......and it is not a tube issue....and I can't see all 4 pots being bad...and by the way, DeOxit didn't do anything for it either.....all the other pots are fine...no noise anywhere.....I should probably start a new thread for this one.....also just to note...this is another amp that has more relays in there than components....They are all over the place....there must have been a huge sale on these relays.......and Marshall must have bought a truck load......

[Chuck H]

The reason why I asked is that I have a problem with a JVM410H...all 4 gain pots are very scratchy when turned..and it is not the type of noise associated with a dirty pot.......it sounds like dc.......and it is not a tube issue....and I can't see all 4 pots being bad...and by the way, DeOxit didn't do anything for it either.....all the other pots are fine...no noise anywhere.....I should probably start a new thread for this one.....also just to note...this is another amp that has more relays in there than components....They are all over the place....there must have been a huge sale on these relays.......and Marshall must have bought a truck load......

It could still be a tube thing. I've had a few tubes. Most were "pulls" that tested good. Bugle boy, Phillips and Telefunken were among the offenders. They seemed to behave fine but would bleed a small amount of DC onto the grid. And it only manifested when the tubes would conduct signal. Idle reading were fine. It's possible that a bad batch of tubes was used for that amp. Disregard if you've already tried different tubes.

I suppose a bad batch of caps could have been used too.

Have you tested for DC on those pots. Not just at idle, but when the amp is conducting signal.

[bsco]

It could still be a tube thing. I've had a few tubes. Most were "pulls" that tested good. Bugle boy, Phillips and Telefunken were among the offenders. They seemed to behave fine but would bleed a small amount of DC onto the grid. And it only manifested when the tubes would conduct signal. Idle reading were fine. It's possible that a bad batch of tubes was used for that amp. Disregard if you've already tried different tubes.

I suppose a bad batch of caps could have been used too.

Have you tested for DC on those pots. Not just at idle, but when the amp is conducting signal.

I noticed that even with no signal, the scratchy sounds are still there.....I didn't check for dc during conduction....I will check that later....Thanks for the reply...I am going to start a new thread for this and attach a couple of schematics.....in the meantime, I'll do some more checking to see what is going on here......
Cheers

[Chuck H]

Check it as you rotate the knobs too Sometimes shifting parameters creates an offset that perhaps acts like DC on the pot. It goes away once the adjusting is done. Does the scratchy noise happen if you turn the controls slowly?

[bsco]

Check it as you rotate the knobs too Sometimes shifting parameters creates an offset that perhaps acts like DC on the pot. It goes away once the adjusting is done. Does the scratchy noise happen if you turn the controls slowly?

It doesn't seem to matter if the controls are turned slow or fast...It sounds like thunder off in the distance with the sound of bacon frying....when you stop turning it, the thunder type sound is still there...but like I said it sounds as if the thunder was off in the distance.......I am going to check out the tubes again...I figure it has to be associated with that first gain stage......I never got a chance to open up a new thread...I will do that later today once I do some more testing......
Cheers