Crackling potentiometers

mannyo

Active Member
I've got a late 1980s receiver which I use for Stereo duties, since I got it the volume and bass controls have suffered from crackling.

Today I got some contact cleaner from Maplin and set about removing the receiver from the bottom of a pile of separates and took the cover off.

After spraying some contact cleaner into the volume control pot, bingo it's fixed and no longer crackles.

But, despite trying several cleans of the bass knob the crackle is still there. I suspect the potentiometer itself as the crackle is now only on a single point, which annoyingly is on the central detent position and only on the left channel. If I try and use the receiver with the bass in this position you can hear one channel sometimes has more bass than the other.

I am now running with the control one detent to the minus side and all is good, well except slightly less bass.

Replacement seems like major surgery as a number of boards are on top of the main board which has the pots.
 

Paul7777x

Distinguished Member
Sounds like it could conceivably be a little corrosion at the centre point, and not just gunk. I'd assume it's been at that position for most of its life.

A few further cleans may help. If not then if you can get the tiniest bit of p2000 wet and dry paper on the contact point... very gently, it may help. Though dry naturally.

However that will only work if it's not a sealed contact. And of course, only if you can reach beneath the top boards.

Realistically though, it sounds like a replacement is the only feasible choice.
 
D

Deleted member 781788

Guest
If you can open up the cover and gain access to the pots, use your contact cleaner there.
There are also plastic film contact cleaners available, that also lubricate and seal.
Check eBay.
DeoxIT F5
 

noiseboy72

Distinguished Member
Trust me, the volume pot will go crackly again in time... the cleaner goes sticky after a while and attracts more gunk. You can squirt them again, but it becomes a vicious cycle.

Worth changing them if you can get to them. Often not as bad as you first think. Get plastic track pots - ALPS are always a good named brand, but be aware of counterfeit copies. These will probably outlive you :)
 

mannyo

Active Member
Thing is with this receiver, the volume control is easy to get at and even remove the whole thing. The bass control is buried, and I could only get the spray on it as I could direct the plastic tube of the aerosol through the wiring to the pot.

To take this thing apart looks difficult, there are so many PCBs in there. The 2380 is the last well made Realistic receiver, so many boards well put together.

When I took this thing apart there is virtually no dust inside at all, and the screws had never been removed until I pulled them. This suggests to me along with the mint unscratched exterior, that its spent a long time in its box and seen little use, especially as it has loads of vents across the top. I have the original box as it was packaged in that when sent to me.
 
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