Basic advice for cleaning an amp?

oreks

oreks

New Member
To start off, I should say that this is my first venture into buying vintage audio gear. I started with a little plug-n-play turntable, but after some reading around I got interested in better ways to play vinyls. I don't have the budget to go full audiophile, so the equipment I've chosen is what came up in my research as having good quality for their price.

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One of the important things for me was having a solid integrated amp for the turntable to plug into. So I ended up getting an old Kenwood KA5700. I've read that keeping these things clean is important for performance, and I saw that Deep Cleaning thread that's stickied on this board. Problem is, I don't have much experience tinkering with electronics.

So knowing that the most I've handled before is using a screwdriver and changing a lightbulb, what could I realistically work on to clean my amp? I'm open to learning new things, but mostly I want to avoid breaking things with my inexperience.

Any and all advice is appreciated :)
 
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Welcome to the wonderful world of Vintage! It's a disease. Amp looks great.

You need to learn how to clean the pots and switches. Lots and lots of threads here. This will solve a LOT of issues; do it thoroughly.

You should also brace yourself to either A) be prepared to do some work on this beast or B) find someone who can do it. It's old.

The 'pull the boards and wash them in soapy water' approach is cool, but is hugely overkill for the average human unless your amp has been used as a breeding ground by mice in the past (happens).

Good luck!
Mike
 
If it's just a little dusty, you can use a soft paint brush and compressed air or Dust-Off to get it pretty clean. I just finished a Marantz 2245 rebuild that started massively filthy. With great trepidation, I followed the advice of a more experienced member and sat in the driveway with a paint brush and Windex. I scrubbed everything and then rinsed with a light spray from the water hose. Who would have thought you could do that?. Sprayed with compressed air for several minutes, and Then I immediately flushed all of the controls with Deoxit several times. Before the cleaning, the unit worked, but was mostly static. After the cleaning, and a couple of days drying in a 100 degree plus garage, it sounded very good with very little static. This was mostly due to the Deoxit treatment. I say all of this to say liquids can be used if you just give them plenty of time to dry. Here is my build thread where you can see the results of the extreme cleaning on the first page, and the finished product near the end. Good luck and plan on getting addicted to this hobby.:beerchug:

http://audiokarma.org/forums/index.php?threads/my-marantz-2245-challenge.727026/
 
Thanks for the welcomes :)

Here's the amp when I first removed the case. Quite a few dust-bunnies, but nothing rusty as far as I know.
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I don't think I'm ready to dunk the board with Windex yet :no:, but Deoxit and Dust-Off seem very doable from the threads I found. I'll probably do a dusting this weekend, and deoxit too if I find it at my hardware store, so I'll keep you guys updated. Thanks for all the advice so far :)
 
Get a combo of Deoxit plus it's sister product, Faderlube F5. Use Deoxit on all switches and pots, flushing and operating controls several times. After blowing that out or letting it dry a little, give the pots a shot of Faderlube to lubricate and protect them. Probably not needed on switches unless they are more difficult to operate than they should be.
 
Looks like the bass, treble and speaker selector switches are all buried under the meters? You may need to drop the bottom panel to get access. It's important that you thoroughly clean all pots and switches... even one dirty one can cause all kinds of issues. I just spent a lot of headscratching time on an old Pioneer that just needed an even better pot bath than I had given it the first time.

Spray into the VRs so that you actually get cleaner inside the wiper section, then work the control back and forth dozens of times. Same thing with switches.

Of course the unit should be unplugged while you do this. Be warned that that the filter capacitors can hold a charge for some time after power down... it's worth learning what the filter caps are and how to discharge them, as they present a shorting and minor shock hazard. The filter caps in tube units hold serious voltage for some time after operation.

Personally, I've had fine luck with the hardware store brand contact cleaner in the past, but YMMV.

If you do end up dousing any of that board with liquid, I would be particularly sensitive about the transformer... not so easy to get dry I would imagine.

Have you tried the unit out yet? Might be worthwhile to verify operation before you start dissecting things so you at least know where you're starting from.

Mike
 
So, I made a trip to Radioshack and got a can of compressed air, but I was also surprised to find Deoxit (I kinda assumed it was a niche item). Then again, maybe I shouldn't have been surprised to find it at an electronics store. No Faderlube though. Anyway, I took that first step of dusting everything, although there's still a very fine layer on some parts. I'll probably wipe those parts down with a cloth.
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I was also going to do the Deoxit today but I wanted to clarify one thing first:
rave0035 said:
Spray into the VRs so that you actually get cleaner inside the wiper section, then work the control back and forth dozens of times. Same thing with switches.
Click to expand...
When you say VR, are you talking about the meters with the moving needles? Also when using Deoxit in general, is it recommended to do it outside (as opposed to a closed room)?

To answer your other questions,

All the pots and switches are pretty accessible from the inside, but I'll remove the bottom if needed.

As for testing it, I've plugged it in and played through the AUX. Unfortunately the entire Right Output seems to be dead. I've seen other threads that explain the reason (like a shorted output transistor). But I'm going to head to bed soon so I"ll probably post a formal analysis with pictures tomorrow.

Thanks again for all the advice, you friendly people
 
NO - Please do NOT spray deoxit anywhere near the meters - you may destroy them !

The reference to VR mean 'variable resistor' or 'potentiometer' - the control potentiometers (VR's) are the metal cylindrical shaped parts behind the knobs that adjust volume, bass, treble, and balance. You need to try to direct the small spray tube of the deoxit into an opening, so it really gets inside the pot - just a quick 1-2 second spray is more than enough, then work the control knob fully, multiple times, and repeat. I normally surround each pot with kitchen roll paper when I do it - to avoid the deoxit spraying everything else in sight as well..... also, remember to give the deoxit solvents time to evaporate & dry properly after cleaning, before powering the amp again. There is a detailed tutorial on using deoxit somewhere on the forum but I can't find it at the moment.... maybe someone else has a link ?

The same applies to the various switches, both on the front fascia and the rear, and the various input / output connections at the rear - essentially all the metal surfaces which are used for your audio signals, should be cleaned.
 
Here are a couple of pics I just took to show you the open spaces in the pots that get the best access to the innards. Not all pots look like this, but most have a couple of openings around the can. And notice that there are actually two pots per control -- one for each channel.

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Sprayed the pots! All the tips here, plus that "Deoxit for Dummies" explained the procedure pretty well. Even though I did see some tutorials where the guy just let the Deoxit drip around the other components, I didn't know if this Kenwood was the same. So I took the precaution of putting some towels to catch the drips.
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I'm wondering if the same procedure needs to be taken with the knobs that are more like switches, like the input knob or the speaker output selector. (The metal box in the lower-right part of the picture).
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I think the last thing I have left to clean will be the faceplate, and all the smudged knobs and switches. Are there cleaners you guys would recommend?
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I'vd used good old purple 409 for faceplates, knobs, and butons for 25 years now. It works great. I normally spray it on a Scott's Blue towel and go to work.
 
You should definitely Deoxit the internals of switches. The contacts get oxidation and they get plain dirty. Deoxit will clean that out and get rid of the oxidation.
 
Update on the pots and switches: it still sounds the same. When I tested it before the cleaning there wasn't actually any scratching when I turned knobs and stuff. So the Deoxit was more of a formality :D. I'm glad I did it though because I feel more acquainted with the insides.

Anway, closed up the box and started to wipe down the knobs and faceplate and such. I wanted to clean behind the Volume knob so I pulled it off. It looks like the last owner had problems with the knob coming loose, because they seemed to have put a candy wrapper or something over the end of the head. I took it off because it seemed pretty informal. But now the knob is loose enough to slide off if I hold the box face-down. Is there a better way to tighten the knob?
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Oh boy. I haven't gotten to the spindle yet because something else came up (Thanks for the suggestion of plumbers tape though).

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The meters are working but... I think they're supposed to light up? I did notice the bulb while I was cleaning. It isn't shattered or anything, but I know bulbs can just die from age. Should I try to replace this thing? I feel like bulbs aren't too obscure of a part.
 
Could I suggest, now maybe a good time to download the service manual (if you haven't already) - there's a copy on the forum database, or the www.hifiengine.com website - it'll make it much easier referring to parts & locations in the amp. There's also plenty of earlier forum threads with Kenwood KA-5700 information / problems / solutions that would be worth reviewing.

It may also be a good time to have a quick assessment of what's working & what's not, e.g., having a meter(s) unlit could be the bulb gone, or (in this case) a fuse, or it could also be a problem with the power supply to the bulb (unlikely here), so it's good to have an 'overview' of what other fault(s) the amp may have. Certain problems can be related, so it can make it easier to troubleshoot - for example, you said previously that one channel wasn't working, but I notice in your video clip that both channels are showing signals on the meters....

For your Volume control knob - I'm not sure if it'll help or not, but the following photo (hopefully) shows a repair I had to make to a Sony knob of somewhat similar design - in that case, I was able to glue (epoxy) the split black plastic in the centre of the knob, and hold everything tightly in place with a small piece of heatshrink tubing - it might help in your case as well, esp. if the central part of your Volume knob is split or cracked.

Sony Knob Repair.jpg
 
I've looked through other threads that talk about non-functioning bulbs. I think I would have to get a volt-meter in order to pinpoint why exactly the light is off. So that will probably wait till later.

In better news, I found out why one speaker wasn't working (and why both meters still moved). It's not the output transistor that's broken, and it's not even the speaker; it's the speaker-wire! Visually, the two wires are exactly the same. But switching the wires resulted in the left-speaker working perfectly. It was frustrating but also a relief to find out the problem was so simple.

The wire in question is the wire that Parts Express shipped with the speakers I ordered (B652 AIR). Unless there's something you guys think I should try first, I plan to just get a new length of wire.
 
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