Lead 12 Mini Stack Volume Issues..

[telemarshall]

Question on an 80's Marshall Lead 12 mini stack - -

Bought my Lead 12 mini stack off CL about a year and a half ago or so. The seller said it worked "perfectly". (Uh, yeah, right..). Upon getting it home I found a couple of undisclosed issues - All pots were scratchy (Deoxit didn't work), and the volume was cutting in and out - on both channels.

So I took the head in to my amp tech who I've used for years (and who usually does a great job), and he seemed to have fixed the problems with some soldering fixes. Happy camper, 65 bucks later.

Fast forward to now - Same exact problems have cropped up yet again... Again, Deoxit does nothing for the scratchy pots, and volume is again cutting in and out..

I guess I'll have to take it back in to my amp guy, but just wondering what might be going on - since the exact same issues have cropped up again?..

Thanks for any input - - !!

 

[BowerR64]

you mention the pots but have you tried the input and output jacks?

I had a MG30 that had this problem and it was the pins on the headphone cliffjack this jack cuts off the internal speaker when you plug a set of cans into it.

when it starts to act up try spraying into the headphone output and insert a jack in and out really quickly and see if it clears it up.

Does it have reverb?

 

[SteelLucky]

If it randomly cuts out at all different volumes it could be one of the input jacks but I can not remember exactly which jack but I think it is the low input. Try deoxit on them. I used electricical contact cleaner in the past on pots with success but haven’t needed to clean the pots on my lead 12 so I guess I am lucky there.

If it cuts out only at high volume and plays better once you turn it back down the bridge rectifier may be degraded and over heating. If so it needs replacement. I also replaced the 6 electrolytic caps and the zenor diode in mine.

 

[telemarshall]

you mention the pots but have you tried the input and output jacks?

I had a MG30 that had this problem and it was the pins on the headphone cliffjack this jack cuts off the internal speaker when you plug a set of cans into it.

when it starts to act up try spraying into the headphone output and insert a jack in and out really quickly and see if it clears it up.

Does it have reverb?

Yep - input and output jacks are scratchy as well - particularly when putting the input jack (guitar cable) in. I will try spraying Deoxit into the headphone jack, and also do the jack thing - Thanks for that tip.

No, this one doesn’t have reverb.

 

[telemarshall]

If it randomly cuts out at all different volumes it could be one of the input jacks but I can not remember exactly which jack but I think it is the low input. Try deoxit on them. I used electricical contact cleaner in the past on pots with success but haven’t needed to clean the pots on my lead 12 so I guess I am lucky there.

If it cuts out only at high volume and plays better once you turn it back down the bridge rectifier may be degraded and over heating. If so it needs replacement. I also replaced the 6 electrolytic caps and the zenor diode in mine.

It cuts out at all volume levels. Deoxit doesn’t help in this case at all (and I’m a big Deoxit fan..).

Hope it isn’t the rectifier, but guess I’ll know something soon, as it looks like I’m going to have to take it in again..

 

[Dino Boreanaz]

I'm curious as to what the problem turns out to be because I've had my Lead 12 Micro Stack for a couple of months now. Mine had similar issues when I bought it and DeoxIT fixed them all. I opened up the head and used a cotton swab to apply the DeoxIT to all the jacks being sure to get between all the contact points before running a plug in and out of each one a few times.

Please post again when you find the cause of the problem as I'd like to keep it in mind just in case mine ever starts acting up again.