RX-5085 Loud rumbling from the right channel only during cassette playback.

M

mu1sic2ian3

Member (SA)
I'm feeling defeated. I bought a 5085 that the radio worked but needed belts. I replaced the belts this morning then found the cassette mechanism was having some issues.
By some miracle after a few hours of staring at it I figure out the problem and was able to get the mech fully working. Cleaned the heads and all that and then
I put in a tape...

I discovered an extremly loud rumbling noise coming from the right channel only. It happens if there is a tape in or not. I feel like its probably the head? Which I think means
I'm screwed?

Here's a video...


Any ideas would be appreciated. Thanks
 
Ghettoman

Ghettoman

Member (SA)
That sounds like the record bar Switch needs spraying with Some Switch Cleaner, You should also spray the function selector switch as well.. that should cure it. if it doesn't, it could be a capacitor issue.. but i would buy some switch cleaner and try that first.
 
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M

mu1sic2ian3

Member (SA)
Ghettoman said:
That sounds like the record bar Switch needs spraying with Some Switch Cleaner, You should also spray the function selector switch as well.. that should cure it. if it doesn't, it could be a capacitor issue.. but i would buy some switch cleaner and try that first.
Click to expand...
Actually I guess I should have mentioned I did spray that already but I could always do it again. Sadly in this case I don't think that's the problem...
 
caution

caution

Member (SA)
Definitely a dirty function or record/play switch. You may need to be disassemble them for a good clean. Here's an example (starts at 6:30)
 
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mu1sic2ian3

Member (SA)
Well I cleaned the hell out of the switch and then tested continuity on all pins and it seems the switch is working just fine, so I guess its back to the drawing board...
 
BoomboxLover48

BoomboxLover48

Boomus Fidelis
mu1sic2ian3 said:
Well I cleaned the hell out of the switch and then tested continuity on all pins and it seems the switch is working just fine, so I guess its back to the drawing board...
Click to expand...


Now replace leaky and old polyester capacitors.... one by starting from the power amplification stage and onwards as needed. Leave radio boards alone.
Be careful with polarity! Take pics and do it systematically with care.
 
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mu1sic2ian3

Member (SA)
BoomboxLover48 said:
Now replace leaky and old polyester capacitors.... one by starting from the power amplification stage and onwards as needed. Leave radio boards alone.
Be careful with polarity! Take pics and do it systematically with care.
Click to expand...
Yeah all capacitors look good. But I guess that's my next step anyway, checking components.
 
caution

caution

Member (SA)
Don't go crazy replacing components quite yet. Make sure first that there's nothing wrong with connections along the audio signal path.
That's the classic rumbling from a poor connection. I'd be surprised if it was something else!
 
M

mu1sic2ian3

Member (SA)
caution said:
Don't go crazy replacing components quite yet. Make sure first that there's nothing wrong with connections along the audio signal path.
That's the classic rumbling from a poor connection. I'd be surprised if it was something else!
Click to expand...
It seems to have a perfectly solid signal, meaning I can hear the audio on the cassette fine on that channel, it just has the rumbling along with it and obviously if there's no cassette in you can hear nothing but the rumbling.

By making sure there's nothing wrong with connections along the signal path you mean check wire connections, solder joints ect?

Sorry I'm still very much a beginner. Spent the last hour staring at the circuit board diagram trying to trace the path of the signal so That I might figure out where to start...
 
caution

caution

Member (SA)
Yes exactly, check the quality of connections and see if there's anything suspicious. Radio Raheem's suggestion is a good one, check that the heads have a good connection.

Just curious, do you have a copy that is in color? If not, check this copy out (link) because it has the audio signal paths traced out with colors.

What does it sound like through the headphone jack?
 
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mu1sic2ian3

Member (SA)
Yes, that is the same version I have. I didn't realize the red is specifically the audio signal path? That should come in handy!

Haven't tried it with headphones actually that's a really good idea. Really appreciate the help everyone, feel like I have somewhere to start.

Will report back.
 
M

mu1sic2ian3

Member (SA)
caution said:
Just to confirm, did you deep-clean the rec/play switch as well as the function switch?
Click to expand...
Yes I did but I may give the function switch another look. I didn't spend nearly as much time on that. I did find a suspicious resistor on the board so I'm going to change that tomorrow when the new ones come in. But that may be incidental.
 
M

mu1sic2ian3

Member (SA)
Hey quick question all.

I just noticed that if I leave it unplugged and off for a day then turn it on, it takes about 15 to 30 seconds for the rumbling to come back after pressing play...
Would that indicate a component on the board "warming up" so to speak? Would this information help me eliminate anything or narrow it down?
 
caution

caution

Member (SA)
Bad connections will do that. It looks like there's a board-to-board connector inside there, if you can find that give it a spritz of contact cleaner.
If it persists, it might be time to start checking electrolytics in the preamp/amp sections. Best way is with an ESR meter, but some multimeters have a cap checker built into them.
 
M

mu1sic2ian3

Member (SA)
caution said:
Bad connections will do that. It looks like there's a board-to-board connector inside there, if you can find that give it a spritz of contact cleaner.
If it persists, it might be time to start checking electrolytics in the preamp/amp sections. Best way is with an ESR meter, but some multimeters have a cap checker built into them.
Click to expand...
Ok thanks.
 
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