Ampex 440B babcock relay replacements?

[JW]

Hey folks,

I'm looking for ideas concerning replacing these relays in my Ampex 440B-2. I've had them go bad in both ch.1 and 2 lately. I've replaced them for the time being with pilfered ones from my 8 track that is on the bench right now, but I'm gonna have to find some replacements.

Here is some info:

They're labeled babcock 'OF-1A-24' Assuming this means a 24V relay. 1A is self explanatory. Here's an auction for 2 on ebay that has been there for months. Ampex part number appears to be 020-592

  http://www.ebay.com/itm/2-Pieces-Ampex-relay-020-592-Babcock-OF-1A-24-AG-440-AP-/220725643349

I'm looking for something a bit cheaper so I can buy a few spares. Any ideas? They don't have to look the same. I can wrangle something up. They have 3 leads on one side, and one on the other.

Also, this is sort of related, but does anyone know what's going on with the Ampex mailing list? Trying to email the owner Howard, and my emails are getting bounced back. My membership got canceled after awhile, but I'd like to join again. Anybody know what's up?

 

[gar381]

  http://www.ebay.com/itm/2-Pieces-Ampex-relay-020-592-Babcock-OF-1A-24-AG-440-AP-/220725643349

Studio Electronics is the real deal but damned expensive.  To bad its not the record relay
thats easy.

Don't know why your Ampex mailing list was cancelled.. seems strange to me.
try this url.....

http://lena.recordist.com/mailman/listinfo/ampex

Best of luck..

GARY

 

[PRR]

> I've had them go bad in both ch.1 and 2 lately

I would have to wonder "why?"

Power supply gone bad is one suspect.

IAC, you want to KNOW the voltage when you shop for replacements.

I'd also wonder HOW they went bad. Did the coil go open? Does the coil work the contacts but there's moth in the works so the contacts don't really contact?

They *look* like Reed Relays.

24V reed relays should be an easy find. The contact rating is not critical, though "telcom" would be better than "power" (I ass-ume, depending what the relay does). The coil resistance should be similar to the originals (if the coil is burnt, this may be hard to know). Though it is likely the relay supply could deliver more current. If only 12V reed relays are now common, you can add a series resistor to split the 24V, though then the relay must be more sensitive (same current at lower volts) to keep the load on the supply the same/similar. Or work-up a new supply of appropriate voltage and current.

 

[PRR]

me> 24V reed relays should be an easy find.

 

[JW]

PRR,

Thanks so much. Exactly the info I needed.

As far as how they went bad, I don't know. I'll test the resistance across the coils to see if I get anything. I just know the machine starting dropping out of record on one channel, and remembered somebody on the Ampex list saying that sort of thing was probably a relay. The only other relay than the big plug in ones in the back that I could find in the 440B electronics was that babcock one. And replacing it with the one from a parts channel fixed the problem. Then the other channel dropped out of record as well, so I had to dig into one of my 440 8 track channels. I hope to not have to do that again. But I wanted to finish a project.

Anyway, last I checked I was getting +39V from the power supply, which is what it's spec'd for,but that was awhile ago. I suppose these are due after 40-50 years for a power supply recap.

 

[emrr]

I think anyone with a yahoo email got cut off from the ampex list, something about an incompatibility with the listserv software, and yahoo wouldn't be coming back online.  May have been some others affected. 

 

[JW]

Well,

Gotta bump this one again. It took me this long to get around to replacing the babcock relay with a reed relay.

Not working though when wiring as per PRR mentioned.

I actually switched the "R" leads to see if that made a difference but no dice. I assume the "C" common leads don't matter which way they're connected?

Maybe I have the wrong side of the relay. . .

They symptom I'm getting now is that when I press record while machine is in play, it actually stops the machine. Weird.

Is there risk of damaging a head or anything here?

 

[radardoug]

Reeds often have the suppression diode inside. If you get the relay coil the wrong way round you will short out the supply.