Analog EQ... Repair or Rubbish?

[sr71rules]

Hello All,

I've had a Tapco 2200 for some time and I used to use it with some frequency until it started to get too scratchy to be workable. It's a Stereo/Dual Mono 10band Graphic EQ that I always found easy to use and, more or less, invisible sounding. I pulled it out of the rack today and did some dissassembly to see if I could get inside and clean it up.

The circuitry is as simple as can be but I'm not sure how to clean up.. what looks like grease... on/in all the sliders. Do they come apart? Anyone every seen them before? Any idea how to clean 'em up?

Do you think it's worth it?

 

[Steenamaroo]

Do you think the tracks are failing, or are the sliders just gummed up with crap?

I had a similar experience with a Concertmate Mg1 synth. The felt dust protector sheet 'melts' and hardens like tar on those things.
I ordered a set of replacement faders but during the wait (2 week US shipping) I actually removed the originals and submerged them for a few hours in hot soapy water. Nothing to lose, right? Obviously I worked each one a good amount in the water too.

I let them dry for a few days and refitted them and - man - that thing was perfect again! In the end I didn't even fit the new faders.


I'm sure there's a more suitable option than hot soapy water but don't give up on it.

 

[mdainsd]

Start with blowing off the whole circuit board with compressed air. That will get rid of tons of dirt.

No, do not try to take the sliders apart. Get a cleaner made for electronics. I use Deoxit myself. Pull a slider to one end of its travel. The cleaner should have a little straw with it to attach to the spray head. Guide the straw down the slot of the fader while dispensing fluid. A little goes along way. Move the fader up to expose where you didnt spray and take care of that area. Then work the fader up and down through several cycles. Repeat on all of the faders. When you are done with that, put the board sliders down on top of some paper towel or somesuch. If you can leave it over night the excess cleaning fluid will drain out of the sliders.

You should be good to go...

 

[The Ghost of FM]

^ Yup, Caig Labs "cali-lube" is what you want for faders.

Deoxit, while being pretty good, is more so for switches and connectors.

Cheers!

 

[sr71rules]

Thanks for the tips!

Jeff - Do you mean "CaiLube™ 360"

Certainly worth a shot... though I'm worried about getting all the crap out. We'll see how it goes!

Robert

 

[The Ghost of FM]

Caig keeps changing their product names so I'm not up on their latest formulations. But if CaliLube 360 resembles what mdainsd was describing as a pump spray with a thin tube nozzle to get it into the fader, then yes.

Also, what was suggested about blowing out the crud with some compressed air is also a good pre-step to do before applying the Caig Labs stuff.

Cheers!

 

[mdainsd]

This is what I was referring to.

DeoxIT® Fader F5

 

[sr71rules]

Thanks All,

I'll take it to work tomorrow and blow it out with compressed air and I'll order some Fader F5...

I'll post back with updates...

Robert

 

[WhinyLittleRunt]

I had a similar experience with a Concertmate Mg1 synth. The felt dust protector sheet 'melts' and hardens like tar on those things.

Oh god, remember that? That stuff was awful... I have been inside several different electronic devices with sliders that had the same foam-turn-tar covering them. Way worse than a gummed up belt or pinch roller.

But I second using the Deoxit Fader stuff; before I knew better I sprayed regular Deoxit Gold into faders and it just stiffened them up worse.

 

[pdmillar]

These are CTS sliders, the same as the ones used in the ARP Odyssey synthesizer (except that in this EQ they have a center detent), where they are frequently found gummed up / dried up / open circuit / corroded / any other problem you can think of. They are more or less the worst sliders ever manufactured by anyone. If you spray Deoxit into them it may improve the electrical action but the spray will react with the existing lubricant and dirt in the sliders to make them sticky and hard to move. The only guaranteed way to restore them is to unsolder them (use a vacuum desoldering tool so you don't lift the traces!), take them apart by uncrimping the metal clips on the ends, and clean the wiper, carbon track, and housing with isopropyl alcohol... being careful not to rub the carbon too hard, because sometimes it will come off! Add a bit of Caig Faderlube to the housing (but not on any of the contacts) before putting it back together... usually the metal clip will break if you try to bend it back into place, so you will need to substitute it with a piece of stiff wire.

(I have had to fix a lot of these on ARP synths! Coincidentally there's a couple of Tapco EQs in the parts pile that I have been pulling sliders from)