Sony STR-6120 reed relay replacement

[spaghetti]

Hi there, my Sony STR-6120 is not working properly anymore, now only the left channel is muted when the FM muting circuit kicks in.

The physical muting of the channels is done via a reed relay, a device I didn't even know existed until it failed, and unlikely regular relays I think it cannot easily be opened, inspected and fixed.
This must be quite a rare issue, I could not find anything on google regarding the failure of the reed relay in Sony's early receivers.

So I went looking for replacements, but could not source an exact match: the original is 12V 700ohm double-throw, and the closest I could find is 500ohm. Would that still be a good replacement? Should I add a 200ohm resistor to match the original 700ohm?

Thanks,
Andrea

 

[loudnoises]

What is the original relay?

 

[spaghetti]

Hi, here's a picture of the original relay. I could not find any info on the exact part on the web.

 

[loudnoises]

oof an axial relay. Unobtanium with that pinout most likely. Maybe find a sony parts supplier with some, but honestly at that age even NOS would be suspect.

Assuming you've tried the ol' hit it with a stick method, and if it is indeed part of the tuning circuit, i'd proceed with caution. very easy to screw up the old tuning circuits. Missed that in my first reading.

You might try posting in the tuner forum, there are a few absurdly good tuner techs there who bless us with their mystical tuner-fu. While you could replace it with any equivalently rated relay and some creative wiring, check with the tuner gurus before you need to pay them for an alignment.

 

[cademan]

 

[I LIKE MUSIC]

"Assuming you've tried the ol' hit it with a stick method, and if it is indeed part of the tuning circuit"

The muting relay is not part of the RF/IF stages of the tuner, it will not affect alignment. It comes after the MPX sections and shunts the audio to ground when the tuner is muted.

The audio signal does not flow through the relay during normal operation.

In general it is not a bad idea not to increase current draw (lower resistance). IIRC it may be a 2sc633 transistor that drives the relay (100 mA collector current). It it likely that even with the increase in current it will be less than 100 mA. You could look at the schematic and check the current budget to make sure that it is okay.

Okay, did a quick search for sensitive coil (low power) relays and found this at All Electronics. I can't speak for the quality.

More searching would likely find more and possibly better choices.



Quality sensitive coil reed relays, even some with mercury wetted contacts show up on the surplus sites from time to time.

The one above would likely work just fine if it will fit size wise. You might have to install it "dead bug" style.

 

[spaghetti]

@I LIKE MUSIC thank you for the tips, I'll try to buy it or a similar one.