Yet Another Marantz 2252B issue - right channel is...crunchy.

schuylercat

Too many systems, so little time...
Dammit.

I bought mine via eBay about 7 months ago and it has been near flawless. Lights are dim on the tuning/signal meters on the left side, but that's a simple fix I planned to do...someday...you know...

Anyway I want to pick the Marantz-Head's brains here: When listening, at any volume, whether speaker selector A or B, to anything BUT the AM/FM section, I get sound drops in the right channel. Tape 1, Tape 2, (tested with RT-707), phono, and Aux (tested with a Pioneer CD player) all come and go on the right. Symptoms are identical regardless the input.

The sound is perfectly clear otherwise, it just sizzles and drops out.

But never, ever, when listening to the radio. I assume the architecture (I can't read a schematic, folks, which is why I come to you) sends radio through a different input than all the other external inputs.

So...when I rotate the source selector back and forth a few time, it goes away. Sometimes. And only temporarily. Dirty pots are on the list, although I was told it was cleaned prior to sale, and all the other pots are without issue - no static, dropouts, dead spots.

Now: I have never had the lid off this machine. If it ain't broke don't fix it, all that. Now it's broke, so I have compressed air, a camel hair brush and ground strap, and DeOxIt standing by. I will give her a gentle but thorough internal cleaning.

Before I do, I would like any and all feedback from the field: am I on the right track here? Anything to look out for? I'm a little nervous about this.

Any and all feedback will be appreciated...

Cheers!
 
From your description I would suspect the mode selector which a Deoxit spraying would be in order. Just a squirt on each pole (circular disk) on each side on the metal parts along with some knob twisting.

The AM and FM has it's own circuitry and then everyting goes via the selector to the tone control amp circuits then to the amps. There's a few more details such as loudness and tape monitor switches but all of it is in common.

If you try out the receiver with the covers off make sure to not touch anything inside unless it's unplugged from the wall. Make SURE no kids can gain access to it. Let us know how it goes!
 
If you try out the receiver with the covers off make sure to not touch anything inside unless it's unplugged from the wall. Make SURE no kids can gain access to it. Let us know how it goes!

Amazing how many people need this kind of warning! I used to be a field tech for a phone company, back in the day. I worked in switches running 220v AC and got bit one time while sticking my hand in between cards to set a dipswitch...and that was the last time I ever did THAT. Still, thanks for looking out for me - I will be careful!

BTW - back in those days we had cans of tetraflourethane we carried everywhere. We'd back out a card, spray the crap out of it, and plug it in ten seconds later - good as new! It was like hosing stuff off in the sink, wet and drippy and immediately dry seconds later. Watched a new kid spray into a live chassis once - he lost his eyebrows and fried a thousand dollar card, but walked away. Oddly funny.

Cheers!
 
Yeaaa! That would have been funny once you were sure he was otherwise okay!

I remember that spray stuff, is that the same as Freon spray used as a cleaner? I remember Freon tanks you could put boards into and scrub off. Worked great!
 
Clean it, but don't drown it.

It helps to get all that gray, sludgy, oxidized grime out by using swabs and paper towels to keep it from spreading. Some cleaners will eventually dry out, but you should be good for a couple years.
 
Yep - Freon stuff it was. It worked like sticking a board under the faucet, and you could watch dirt, dust, dead bugs wash away and the board looked like it had just come from it's last acid bath.

Update - I completed a full cleanup, as best I could, anyway. The input selector is an easy reach, and I blew it out, hit it with DeOxIt, rotated the knob a bit, then worked on other issues. I'm gonna post a write up with pics - this machine was a.) in the company of a smoker for a long time and b.) someone did a relamp and broke everything they touched inside.

Anyway, I did a second scrub of the input selector, after hitting every push button, tone controls, balance, volume: everything. Hit the speaker selectors, in case there's weird thing in there. The MONO button, which could...I dunno, something.

Put it together, set it up, played 2 CD's and a RTR of Gershwin without a single problem! Clean, clear, nice!

Put on an LP and the right channel cut out after 20 seconds.

Dammit.

So I worked the knobs. The input selector mostly, but every knob there is because I figure I cleaned it all, it all needs to be worked. Should I, after spraying a blast of DeOxIt, work a knob a LOT (50-75 times back and forth) or a little? I worked them back and forth 15 times or so. Is the cleaning cumulative?

Which begs another question: since ALL inputs, including tape, cut out the same way, the input selector (which does not control tape monitoring) couldn't be the issue, right?

I so pissed. Idears?
 
I use the straw thing to spray little amounts into the pots, then turn the knobs, wipe excess off and repeat a couple of times. I don't know about using freon and freezing old delicate, sometimes brittle parts.

I also clean all the RCA jacks in the back with a DeoxIT and cotton swab, not Q-tips. I have a little bristle brush I got at Fry's Electronics that works perfectly for scrubbing inside the jacks.

Not sure about the input selector.
 
I use the straw thing to spray little amounts into the pots, then turn the knobs, wipe excess off and repeat a couple of times.

Done this, with limited results. I suspect my problem is deeper than a cleaning. Sad, me.
 
Just a thought, but is it possible that the tuner working without drop-outs is a coincidence? If that's a possibility, I'd suspect the speaker relay is dirty and needs replaced. When it acts up, grab it and give it a jiggle.

I cant recall if this receiver has jumpers on the back, or if the preout and main in are make/break internally... Clean those also.
 
My 2252B drops out at the Tape Monitor button. It's always the first one to need cleaning. One of these days, I'm going to get ambitious and remove, disassemble, clean and re-assemble that switch.
 
Well rats! Either of the two above items could be the issue. If not the next item would be the tone control amp. It could be a bad cap or transistor and switching the selector could provide just enough of a dc shift to maybe make it work again.

One thing to try is to use a pair of RCA cables and plug into the left channel preamp jack and connect to the right power amp jack and vice versa for the other cable. If the dropout stays the same it's past the preamp stuff and is likely something in the amp. If it switches channels I bet it is on the tone control board.

To get at that board to work on it requires all of the knobs to come off then undo the faceplate bolts, being careful to not scratch the faceplate. One tip there is to put on some masking tape first. Then the nuts on the front for the tone pots come off then the board is free. I have not worked on this exact model so am not sure if the wire connections are on a plug in connector or hard wired. Then it can be de-oxed or recapped or whatever.
 
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It could be a bad cap or transistor and switching the selector could provide just enough of a dc shift to maybe make it work again.

This. I feel that when I flip the selector to FM, which is tuned to a clear station, the spike in volume causes a...recharge, I guess.

One thing to try is to use a pair of RCA cables and plug into the left channel preamp jack and connect to the right power amp jack and vice versa for the other cable. If the dropout stays the same it's past the preamp stuff and is likely something in the amp. If it switches channels I bet it is on the tone control board.

This is me, shaking my head, thinking "why didn't I think of this?" Good catch!

And best of all - I listened to CD's all night last night after my weepy-eyed post, and have been listening all morning to LP's, and the problem seems to have cleared. Is it fixed? Did the DeOx work? Will I ever play the violin again? How the hell do I know?!

If it acts up again, I'll heed this advice. For now I am happy to have an uninterrupted afternoon of listening - God I love working from home!

Thanks everyone for the feedback - it was an exciting first foray into my sickly Marantz. I have pics too - I may blog the fix.

Cheers!
 
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