cleaning a relay

keithpgdrb

keithpgdrb

Super Member
I need to clean the protective relay in my vintage amp. I have read many threads about burnishing the contacts, as well as just replacing the relay.

I recall having seen one thread that describes cleaning the relay with alcohol. I have some 99% isopropyl. I do not believe this leaves any residue. would this be acceptable to try? or should I just lightly burnish and be done.

who can offer some advice. I'm not replacing it at this time. unless I break it. I'll have to try to find a replacement part for it as well, so forget it.
 
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When relay contacts become oxidized, it is because the gold plating on the contacts has burned off, leaving the next layer exposed. If you clean them they will become oxidized again in a month or 2, because there is no gold to protect them. If you put De-Oxit on the contacts it will attract dust and they will become intermittent again in a couple of months. It is a waste of time to clean the contacts, just replace the relay. If you give me the numbers on the plastic case of the relay and tell me what brand and model it is in, I may be able to come up with a replacement. Digikey stocks most of the relays used in both vintage and modern amps and receivers.
 
dr*audio said:
When relay contacts become oxidized, it is because the gold plating on the contacts has burned off, leaving the next layer exposed. If you clean them they will become oxidized again in a month or 2, because there is no gold to protect them. If you put De-Oxit on the contacts it will attract dust and they will become intermittent again in a couple of months. It is a waste of time to clean the contacts, just replace the relay. If you give me the numbers on the plastic case of the relay and tell me what brand and model it is in, I may be able to come up with a replacement. Digikey stocks most of the relays used in both vintage and modern amps and receivers.
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hey Warren,

thanks so much for checking this out for me. Here's the info:

Type MS4U
24V DC
257-12
36
Japan

I think the brand is DEC.
 
Can you take a picture of the bottom of the relay or the bottom of the board it mounts on, so I can see the pin arrangement? Also what brand and model number is the amp / receiver this is for?
 
dr*audio said:
Can you take a picture of the bottom of the relay or the bottom of the board it mounts on, so I can see the pin arrangement? Also what brand and model number is the amp / receiver this is for?
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I wont have time for a day or so to start taking the amp apart. I'll get you a pic when I do. the amp is old. its a Sony TA-3650

http://translate.google.com/transla...T/amp/ta-3650.html&sl=ja&tl=en&hl=en&ie=UTF-8

http://www.thevintageknob.org/SONY/sonyvault/TA3650ST3950/TA3650ST3950.html
 
It is 'probably' a 24V, 4PDT 'MY'-style relay, replacable with an Omron MY4-02-DC24, but this should be confirmed.
 
As I recall from my telephone plant days (Relays? Oh yeah we got relays.) the thing that keeps contacts clean is when the contacts 'make' before the armature hits the core. This provides a 'wiping' action and tends to keep the contacts cleaner longer. Many protection relays seem to have lost that follow through and the contacts barely make just as the armature hits the core.
 
I tried to clean the relays using a piece of paper as sandpaper. I read this somewhere. still looking for a replacement relay. I cant find anything. anyone else?
 
I would need to see a photo of the bottom of the relay to be sure, but I think this relay will be an exact replacement:
Digikey part# Z2634-ND MFR part# MY4-02-DC24. This will work for the Sony TA-5650, which is in the same series as yours, so it will probably fit yours as well.
 
I could not get a clear pic of the underside of the relay, as I couldnt get the board out gracefully. I did my best though. as I looked at it, it seems to be two rows of 4 pins, then a couple pins on the corners. hopefully you will be able to see, I had to take the pics at an angle.
 

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NC = Normally Closed in relay parlance. NO = Normally Open. Common = The pins that make connection with one of the other two, depending on whether the coil is energized or not.

On an MY4 relay, the pins closest to the coil pins are the Common. The next row up is the NO contacts, and you can guess the last row.
 
OK,

so, while I was trying to figure out how to get the board out to remove the relay, I noticed that on the back of the heatsink, there was a wire that was disconnected. Now, I dont know enough to know what effect this would have, but I am wondering.. when I was tapping on the relay, listening to the sound come in and out, could it have been the loose wire bouncing near the contact making the noise?

so, to find out if this is actually the problem, I must power the amp up with the repaired connection. So, here is what I need to know.

1. I have included a picture of the back of the heatsink. the wire came from the bottom of the silver thing on the back.

2. the other picture is of the wire that was disconnected, and one from the next section that was intact. so, a good one, and a bad one.

3. you can see that one wire has a darkened amber color, and has disconnected from its "O" connector. the other is a bright yellow and is intact.

4. What is the yellow material on either wire? Can I just solder the O connector back on the old wire, or is the yellow substance some kind of compound I am supposed to use. I would like to just solder it back together and see what happens when reconnected, but I dont want to make an unstable connection.

Sorry for the blurry pictures. my camera is unable to focus apparently.

ANY help on this is VERY appreciated! Thanks in advance. :yes:
 

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The 'yellow thing' is a thermistor, to monitor the temp. I don't know what amp this is, so I dunno is it modulates the bias current, or disconnects the relay. Regardless, if it's undamaged, it should be glued to the ring terminal. Use a bit of JB Weld to get it done after you carefully clean both parts.

keithpgdrb said:
do I pull the pins out, or clip them as short as I can?
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You'd be tugging on them a long time to pull them out. ;) Use a nice sharp pair of side cutters and clip off the unused pins.
 
Hey Echowars,

I made a bit of a faux pas in throwing another topic question in the mix here. sorry about that. I should have posted a new thread..

So, on that note, I've watched the video clips at tangents website about removing componants, but there is no great example on removing something with this many points. might you, or anyone, have any suggestions on how to get this relay off the board when the time comes? are there other video demos elsewhere?
 
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