Fender Concert Amp - Cleaning pots

[Mars Amp Repair]

Hey folks,
I[ have to think there are other techs that have thought of this method, but just thought I would share this 'Hack' as they call it today for cleaning the pots on this freakin' ridiculous amp w/o removing boards.
You may know that the main board in this amp is one large board that all the tube sockets are soldered to as well as two tubes that have sockets screwed to the main chassis with wires going to the main board.
In order to get to the pots on the front board, you must removed the main board which is quite the process.
I used a method I used back in the 70's with hifi receivers that also needed boards removed on order to access the pots.
See the attached pic.
I take a small drill in a pin vise & CAREFULLY drill a hole in the position shown in the pic, then spray the DeOx thru the hole.
You must of course take your time and be very careful as you approach breaking thru the top of the board that you don't jab the drill bit into the pot.
Even though there are 12 holes to be drilled, it is still less laborious than removing all the necessary screws, jack nutz, & the two tube sockets not to mention the transformer connections. It also avoids creating a new problem dangling the board in order get to the front board & then remove it.
glen

[TomCarlos]

Interesting idea... I assume the pots are "open" and you can shoot the cleaner into them? We've seen some pots recently that are of the "sealed" type. I also put a dab of cleaner/lube on the pot shaft. That seems to loosen up some of the friction as you turn the knob and in some cases, the cleaner drops down into the cavity.

[SoulFetish]

Interesting idea... I assume the pots are "open" and you can shoot the cleaner into them? We've seen some pots recently that are of the "sealed" type. I also put a dab of cleaner/lube on the pot shaft. That seems to loosen up some of the friction as you turn the knob and in some cases, the cleaner drops down into the cavity.

I've done it a couple of ways. The first is thing I do is take some of the insulation off inner romex wire, cut a couple of 1.5" pieces, and use them as couplers to extend the Deoxit tube putting 2 or 3 together. I can curl the end and get "close enough" under the board. Not as efficient as a precisely drilled hole I'd imagine, but it works none the less. I've also gone in through the pot shaft as well. I'll generally place some sort of tube that fits over the pot shafts to try and keep the deoxit in a concentrated area.
I like your idea of creating an access hole, but if I were going to do that, I would buy a carbide stub drill just larger than the diameter of the Deoxit nozzle tube, and use it with a stopper so that no damage can be done in case the drill wants to run in on me

[Mars Amp Repair]

Anyone who's ever worked on one of these amps will know what I'm talking about.
I also have extended the tube on my DeOx tube as have many I suppose, and snaked it down where all the pots are, however this amp is very unique. I'll have to post some pix of the entire bottom of this unit & you'll see that there is no way to access these pots without removing the board they are mounted on and you cannot get this board out without removing the main board, which in this unique Fender Concert amp, is a real project.
Since the chassis set up & pots are standard Fender style, yes, there is an opening in the bottom of these standard pots. I know this as I had one other of these Concert amps that needed a few pots replaced, and I had to go thru the painful process of the necessary disassembly as described above.
I also have narrowed the tip of the spray extension tube by putting a common needle in the end & then heating and stretching it thereby reducing its size so it better fits in the drilled hole. You can of course just hold the tube perpendicular to the hole & press it up against it and the results will be the same.
Thanx for the responses.
I'll post more pix tomorrow.

[The Dude]

So, would that be a considered a pothole?

[SoulFetish]

So, would that be a considered a pothole?

Heyooooh!!!

[Mars Amp Repair]

Pic of Fender Concert underside. Pic worth 1000 words .

[SoulFetish]

Yup, I totally get it now.

[Mars Amp Repair]

Yep...a design mess! Here's the topside pic for good measure & pic of the reduced sprayer end for the heck of it. Thanx for responses...glen

[g1]

You can do miracles with lengths of heatshrink and some tag wire running inside of it. Easy to bend around corners unlike the stiff plastic straw. Just heat the portion you attach to the straw. The tag wire will hold the heatshrink straight but can be bent or curved as required. Just as long as you don't kink it and block the flow.

That being said, from the description I was expecting this model to be all one board like the Super 60.
Can't you drop the controls board down and tilt it so you can clean the pots? I seem to recall doing that but could be mistaken.

[mozz]

Where is the tool that fits over the pot shaft and then you spray into it? I know it was brought up before, can't remember who sells it, Stewmac? Also hope you guys know about WD40 specialist contact cleaner, no more deoxit for me, the D100 bottle is still 3/4 full i got 20 years ago.

[Mick Bailey]

Those Fender Concerts are on my list of amps where my heart sinks and the sky clouds over whenever I got a call for one. Any ideas for shortcuts are welcome - these damned things eat up time if you have to remove the boards.

[Mars Amp Repair]

Where is the tool that fits over the pot shaft and then you spray into it? I know it was brought up before, can't remember who sells it, Stewmac? Also hope you guys know about WD40 specialist contact cleaner, no more deoxit for me, the D100 bottle is still 3/4 full i got 20 years ago.

Well as mentioned, with that method, at the very least the viscus lube on the shaft will be dissolved and the pot will not longer have that nice drag on it...Even if the deox or whatever can actually get down the shaft to the pot, it's no guarantee it will actually get to the carbon track where the issue actually is.
Just seems like a bit radical method when there are other options.
But as Mike Bailey stated, any help on these beasts is well taken!

[Mick Bailey]

I really don't like the lube-down-the-pot-shaft adapters. In my view they do more harm than good in dissolving the grease on the shaft (which can sometimes be contaminated with dirt and metal particles) and depositing this on the track where its not wanted.

[SoulFetish]

I really don't like the lube-down-the-pot-shaft adapters. In my view they do more harm than good in dissolving the grease on the shaft (which can sometimes be contaminated with dirt and metal particles) and depositing this on the track where its not wanted.

IMO, it's a last resort and certainly not ideal. I've never experienced it causing any lasting problems. I've found that the grease on most pots can reset after some time and drag restored (at least to some degree), but even spraying into the back of the pot can cause this problem.
Drilling an access hole in the PCB is a better solution, but like I said, I would just make an acrylic depth-stop and use a carbide stub drill for safe, consistent results which could probably find use beyond just this model.