Akai GX-4000D pcb cleaning.

[Kentode]

Hi, I'd like to ask for some advice.

Should I clean the component side of this pcb or should I leave well alone?

If I should clean it, what are your recommendations?

I'm wary of the fact that the variable potentiometers may be brittle and might break if manhandled.

All advice gratefully accepted.

[60 oldjohn]

Hi Ken, I would gently brush it with a new 0.5 wide, inch long bristle paint brush and occasionally and giving it a gentle blow if anything breaks it needed changing anyway! See how you go to decide next step.


John.

[Mooly]

The presets may well be suspect before you even begin suffering from loosened rivets where the resistive track is clamped to the pins and also loosening of the tabs that secure that pressed tin wiper.

Personal opinion (YMMV and all that) but I would strip that unit down and thoroughly wash the board in hot soapy water, rinse and then dry. And do the same for as much else as was feasibly possible.

[Radio Wrangler]

Hot soapy water is good. Flow solder line making pcb assemblies used to use dishwasher detergent. HP even specified that components had to withstand Calgonite,However pots and switches won't like a trip in the dishwasher and the stuff etches aluminium. I now use electrolube or RS foam cleaner. But anything which will shift the muck will degrease all the lubricant out of your switches, but that can be restored.

Amateur radio gear was bad. People sat right in front of their sets puffing away chain smoking... particularly high tar gaspers at that. The tar got inside by the cooling airflow. Dust and muck stuck like..... yup, like that.

David

[Grubhead]

You can get cans of aerosol dusting sprays from Maplin electronics. You will have to use Servisol Video 40 on the switches though, after you have cleaned the muck off first. Don't use it first, or you will have a sticky mess all over.

[Kentode]

Thanks for all your inputs, I'm going to go for the soft brush option, being extra careful around the presets.

John, hope to see you at Golborne.

[jlanders]

If you know anyone who has an Ultrasonic Cleaner, that is another option. We have run tests in our workshop with good result

http://www.kemet.co.uk/blog/cleaning/pcb-cleaning

[vidjoman]

I prefer a soft brush and vacuum cleaner. The dust gets sucked up instead of going elsewhere.

[Kentode]

Here are the results of using a half -inch flat artists brush and vacuum cleaner.

[60 oldjohn]

Originally Posted by Mooly

The presets may well be suspect before you even begin suffering from loosened rivets where the resistive track is clamped to the pins and also loosening of the tabs that secure that pressed tin wiper.

I do not know this player but if it is from 1970s - 80s I would consider changing and setting them up to ensure reliability. My experience with B&O equipment indicates that this type of pre-sets are a weak point.


John.

[Kentode]

Right now I'm waiting for delivery of some new capacitors to replace the swollen Rifa film caps in the power supply and auto shut off.

Those presets rwill be left until I can record some test tones and establish a baseline from which to decide what needs doing John.

There is another thread somewhere mentioning fragile presets, possibly RevoxA/B 77.

I'll do some searching whilst I'm waiting.

[monaro0162]

Good luck with your restoration, I shall be watching with interest. On the pots, the 4000DS uses what look like bigger encapsulated pots fitted to the other side of the pcb, with small adjuster knobs fitted, so you don't need to use a screwdriver through the pcb to adjust them. May be more reliable? I've had no trouble with them on my DS.

[Kentode]

Thanks Monaro, but I doubt that you'll learn much from me!

On the plus side, I will gladly donate my Rotel R-320 in exchange for a picture of your presets, both sides!

It's redundant since I bought and repaired / converted to stereo my Leak Troughline II.

[monaro0162]

Thanks for the offer Ken. I have a spares MK1 with amp pcb that I will photograph this evening.

Paul

[Kentode]

Cheers Paul.

[monaro0162]

Photo of the amp pcb with pots attached. (They aren't encapsulated, my error) There is nothing to see on the other side of the pcb, no through hole above the pot, just components on the other side.

[Kentode]

Thanks Paul, if I do have to replace any presets I might just put them on the underside.