How I clean Adcom GFP-555 and GFP-565 record and playback selector switches

Posted on by hoppesbrain

Hey folks, I hope this will be useful to anyone attempting to clean an ALPS sliding listen/record selector switch like those used in the Adcom GFP-555 and GFP-565. These are common in many brands of preamps and receivers.

Ribbon slider-switch inside GFP-555.

These are nice switches, but they do corrode after a while. You can sort-of spray some De-oxit in there, and that may work, but I don’t want my customers calling me back in a few years to complain that the problem is back! So, I take them apart and clean them thoroughly.

These aren’t even that badly corroded.

 

The first step is de-soldering the switch from the board. Be careful, it is very easy to damage the solder pads. I use a Hakko vacuum de-soldering station, and it usually leaves the pads undamaged. Be very careful bending the pins, as they break easily. Sometimes a few of the pins will be bent to hold the switch in place during wave-soldering. I remove the solder and carefully bend them straight.

The switch should come free after all the pins are de-soldered, including the four anchor points on the corners.

Now to crack open the case. I don’t have pictures of this step, as I don’t have a third hand to hold the camera. The phenolic board is held in place by the eight steel tabs around the outside. These are simply bent to hold the board in place. I use a long needle-nose pliers to gently bend these tabs straight. Once these tabs are straight, pull the phenolic board up and away from the metal body.

The black plastic piece shuttles back and forth as the selector knob is turned. There are little metal clips that ride along to contact the terminals for each switch position. Remove the shuttle and the little clips and set aside.

Cleaning:

I buff the corrosion away with No7 White Polishing compound and a cotton swab. The fine-abrasive polishing compound leaves a smooth shiny finish on the nickel plating without wearing too much off. Clean afterwards with a toothbrush and alcohol. Make sure there’s no gunk left between the little tabs.

Cleaned on the left, not on the right. This switch is actually pretty good to begin with, and was not causing any problems. But they can be much worse, turning nearly black in high-humidity environments, especially near oceans.

Re-assembly:

Spray all the contact surfaces with De-Oxit D5 or similar, so there is a film of protective lubricant coating the metal contacts.

Turn the selector knob all the way to “Phono”. There is a metal tab that aligns with a slot in the shuttle.  Drop the shuttle into the case onto this tab. Align the little slider-clips with the tabs as shown.

Gently coax the board back into its case, being very careful that the clips slot into the plastic shuttle without pinching.

Bend the eight tabs back into place with the needle-nose pliers. Be careful not to damage the casing, but I’ve found you can pinch gently against the nylon housing on top without damaging it.

And solder it back in!

Enjoy the smooth switching.

 

 

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