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-   -   Cleaning Switch in High-End Sony Preamp (http://www.diyaudio.com/forums/solid-state/155615-cleaning-switch-high-end-sony-preamp.html)

thermionic 24th November 2009 09:29 PM

Cleaning Switch in High-End Sony Preamp
 
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Hi,

I'm in the process of refurbishing a Sony TAE-88 preamp. It's a good example and just needs cleaning (I wonder if it was owned by a smoker...) and a re-cap / check of all caps / re-calibration. The switches are noisy, but they're very well-built (like the preamp in general) and I reckon they'll come up like new with a drop of Deoxit D5.

Has anyone here cleaned these switches before? I'm pretty sure I could just use a Deoxit pippet, gently dropping in solution and turning the switch. However, I'd like to know if there's an accepted standard for cleaning these switches out?

Thanks in advance.

Mooly 30th November 2009 11:48 AM

They dont make them like that anymore :)

Switches... I would unsolder and put them in a container and flood them with WD40... which doesn't attack plastic and really work them hard to clean them up.

Depending on how experienced you are, did you know you can perfectly safely "wash" PCB's to bring them up as new. The only things to be careful of are coils (as in adjustable ones in tuners etc) and trimmer caps etc, "sealed" pots etc. Transistors, caps, IC's, all OK

I like to use foam cleaner and a brush, then rinse well in warm water and place in/on hot radiator or very low oven <45 degrees C to dry or use a hair dryer. Cleaned dozens of TV chassis this way that have been damaged by spillage etc ... even with the high voltage parts and done properly gives good result. They look brand new.

analog_sa 30th November 2009 03:03 PM

Quote:

Originally Posted by Mooly (Post 1997071)

put them in a container and flood them with WD40



It will be much more difficult to remove the WD40 residue after this "cleaning" :)

Deoxit seems like a safe and easy choice.

thermionic 30th November 2009 05:34 PM

Hi,

Seeing as I couldn't find anything on the web, I had to figure this out for myself. The plan is to desolder them (I have a pair of vacuum desoldering machines) and bathe them in Deoxit. It's a huge job... You also have to note the cam positions before disassembly as the chance of reassembling everything in sync is equivalent to cracking an enigma machine. The manual lists tables to aid with this.

I've now cleaned out the attenuators and re-greased them with Faderlube - as well as a full re-cap of all electrolytics. Next step is to check ESR of all tants.

Interestingly, following electrolytic replacement, I can't measure undue offsets at the test points, which must be testament to Sony's design team and general component quality. Offset at the main O/P is under 10mV on one channel and near-zero on other. The resistors are pretty unusual: metal oxide film types. I shudder to think what a similar unit would cost to sell today...

Cheers,
Justin


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