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Yamaha CR-620 Cleaning Question

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seafrost

New Member
Picked up this receiver for $40 off craigslist in working condition. When I opened it up I counted 7 spiders crawl out, about 10 cocoons on the bottom, and a layer of dust so thick I couldnt see the components. So i got to work on forums seeing how I should clean this. Some people said to spray alcohol from a spray container directly onto the circuitry so heavy that there is run off and then go over it with a paint brush. Is this too harsh? I feel like thats a bit intense for the components. I just used a qtip and went through things gently.

Second question is, the knobs/faceplate/top grills are covered in some sort of smoking/rust type residue. I dont want to spend a bunch of money on new knobs since I see a lot of people pick these things up for $5 at thrift stores, but I really love the looks of this thing and want to make it shine. How can I clean these knobs/dials?

Third question, the lights on the front are out. How do I gain access to them and how hard is it to replace the bulbs with some nice LED's? I have advanced soldering skills (ive been repairing TV's/building guitar pedals for a few years now) just never worked on receivers.

I know im asking a lot for the new guy but hopefully some people can help. If anyone is going to help me, it will be the members here. I posted pictures below so you guys can see what im talking about. Thanks in advance

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Pull all the knobs off (1.5 or 2 mm setscrews) and let them soak in a tub of hot water and simple green-use a toothbrush to scrub off all the smoke& tar stain.Remove front panel and wipe it down with the same -Hot water and simple green. I would blow out the bulk of the dust with a air compressor at 20 psi with the assistance of a soft bristle paint brush The last thing you need to clean is the switches and controls with deox-it. Once you get the front panel off you will see how to gain access to the front panel bulbs. Contact AK'r dgwojo for the correct replacement lamps.
 
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My 620 wasn't as dirty, but I would soak your knobs in some soapy water.

For a little extra buff/shine use a dry magic eraser, I did on my knobs and faceplate and it works great. No scratches or removal of the labels.

avionic said:
There are 4 lamps - 3 for the meters and 1 for the pointer.They are 12v @ 60ma.
Contact dgwojo and he will hook you up with the correct bulbs.


http://sportsbil.com/yamaha/cr-620-s-2.pdf
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If I remember right, the knobs pull off, but the switches has set screws. I didn't take my switches off to clean them, tho.
 
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LeeVing said:
My 620 wasn't as dirty, but I would soak your knobs in some soapy water.

For a little extra buff/shine use a dry magic eraser, I did on my knobs and faceplate and it works great. No scratches or removal of the labels.



If I remember right, the knobs pull off, but the switches has set screws. I didn't take my switches off to clean them, tho.
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I totally strip them down for cleaning.Allows easier access for recapping and deoxing switches and controls.
 
wow thanks for all the help guys. i went through 2 bottles of canned air to get all the interior dust off and then like I said, used cotton swabs dipped in alcohol. would you hurt anything by putting alcohol in a spray bottle and spraying down the insides? also I have a radio shack brand electronic cleaner and lubricant...is this as good as deoxit or should I go with the trusted stuff? thanks again, this forum is amazing
 
I just cleaned some R-700 knobs that a fellow AKer bought from me. I used Blue Magic metal polish that I got from Pep Boys. Trust me it works great. I have never found that soap/water, windex, alcohol, etc worked that well. This polish has never affected the lettering on my faceplates either.

Check out my avatar. That Spec gear originally was yellowed.
 
I got those knobs in the mail yesterday (thank you) and they look brand new. Now I need to pull the existing ones and polish them so they all match.
 
You can take all the knobs and let them soak in soap and water and then get some Turtle Wax and polish them and that should make them look good and clean.

Congrats on the 620!
 
thank you so much for all the help guys. I went with the soap and water but the stuff we pretty caked on. I got blue magic liquid metal polish from pep boys and within seconds everything was gone! definitely worth the $7. Ill post pictures here once it is all cleaned up.

But now im having another problem....I cant get off the "balance" knob or the tuning knob. Maybe they are caked on and im not pulling them hard enough, but I dont want to find out the hard way. I am trying to take off the face plate I can scrub that down too. If any of you guys know how to remove those 2 knobs let me know, and again a million thanks for the help so far

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Check for set screws behind the faceplate on the knobs shaft. 1.5mm or 2 mm...If no setscrews ..Then get two tablespoons and pry the knob off - they are real tight fitting knobs.
 
when I get a unit that looks like that, I take all the knobs and put in a large bowl, HOT WATER and a TABLESPOON of CASCADE Dishwasher Detergent. Dissolve the Cascade, then drop the knobs in. Stir occasionally, and 15 minutes later, they are clean. No scrubbing, no brush, no muss no fuss. You can actually see the water turn brown!! Some are worse than others.

The Front piece gets doused with the same solution before the knobs make it too dirty, sits for a couple minutes wipe with Handi Wipe, then rinse in HOT WATER. Found over the years that 1.) Body oils love cold or Warm water. 2.) Cascade and Hot water will cut thru the grime and body oils, and leave a clean finish, 3.)NO SPOTTING when drying and 4.) It doesn't lift the lettering like some other detergents do. . Use a microfiber cloth to polish it up.

Larry
 
If you're not yet happy with the state of the interior, the next step I'd say is soap and water. Wet it down, then have a pan or bucket of hot soapy water and some paintbrushes. Apply soapy water, then work it with the brushes. Be gentle, don't break anything. Take some care not to get it into relays or down the chokes and coils too much, or into middle of transformer, just cause it could stay there and make rust. Work briskly, you're cleaning it, not drowning it. Rinse well with clear water. Let it drain, turning from time to time to let any water that's stuck somewhere find a way out. Give it time to get totally dry before energizing, of course. Speed this up with forced air, or hair dryer, or even a 170 F. oven (not hotter).

Lots of water beats a little alcohol, when you've got major dirt to contend with.
 
I've seen posts before showing pictures of repair companies washing down radio transceivers and the like, in special parts-washing stations.

If you have to pry the knobs off, protect the face with a cloth around and behind the spoons. I think there are some other tips in the deoxit sticky thread as well.

Also, I've noted computer stores that do a lot of repairs that have rigged up compressors with air guns to clean out computer cases - one even had the coil hose piped up to the front door (I don't think that shop has a back door). So one might want to take a really dirty component over to your friendly computer shop and ask nicely.
 
seafrost said:
thank you so much for all the help guys. I went with the soap and water but the stuff we pretty caked on. I got blue magic liquid metal polish from pep boys and within seconds everything was gone! definitely worth the $7. Ill post pictures here once it is all cleaned up.

But now im having another problem....I cant get off the "balance" knob or the tuning knob. Maybe they are caked on and im not pulling them hard enough, but I dont want to find out the hard way. I am trying to take off the face plate I can scrub that down too. If any of you guys know how to remove those 2 knobs let me know, and again a million thanks for the help so far

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Two spoons for the balance knob, it always sticks after a number of years. Look behind the faceplate on the right side, tuning knob has two Allen set screws 2MM but a 5/64" will work. Along the bottom of the faceplate four screws, across the top three screws.
 
merrylander said:
Two spoons for the balance knob, it always sticks after a number of years. Look behind the faceplate on the right side, tuning knob has two Allen set screws 2MM but a 5/64" will work. Along the bottom of the faceplate four screws, across the top three screws.
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I've got a CR-620 I inherited from my dad. I tried my best to deoxit the volume and balance pots to eliminate the volume knob crackle and an intermittent drop-out/distortion from one of the channels, but it didn't really 'take'. Is there a trick to getting the deoxit up into the pots or do you think i may have a different issue?
 
For some reason, I've seen a lot of old Yamaha stuff with bad worn out pots, usually volume, for obvious reasons. My old receiver's volume pot had two issues, one, the mounting nut was loose and then later on, the volume control wore out way sooner than it should have, so I replaced it. If De-Oxit didn't work, it's probably just a bad pot. If the spray didn't get in there, I don't know what else would.

My "new" SA-500 is really nasty. It's like the dust is glued on. A brush and air isn't working very well. I've never seen anything where the fuzz is glued on like it is on the SA-500. It seems doubly odd because there isn't any noise from any of the controls that usually have problems, and the switches all work perfectly. The only operational issue is the crunchy tuning cap, and it seems to be on the warm side from all the fuzz on everything. I really don't want to take it all apart....sigh...
 
Sometimes a fair bit of disassembly is required, when 'spray and pray' doesn't do the trick with deoxit. There usually are vent holes on the sides of pots. You obviously don't want to have to remove and replace connectors just to clean a thing, but I've done everything short of.

And as observed, while deoxit can work miracles, there are problems that are beyond it.
 
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