How to properly source a relay?

[Mr_bibbles]

Hey folks, I am trying to source two separate relays but am pretty confused on how to select the correct parts... I've never done this before and am really just hoping to avoid rookie mistakes.

I know I'll need to match the voltage, account for amperage, Pole/throw type and size but... where do you go to source amplifier relays in the US? Newark?

I need a "24VDC DPDT" marshall 9100 relay (That's all the info the schematic has) and a mystery Hi-Watt relay. It's for a Lead 50R, but searching the old schematics (even trying to find a close model and YS I used the Hiwatt site ;0) is yielding nothing. The SN on the relay doesn't being up anything on google, but it looks like a standard size DPDT 6V relay and has "66 Ohms" on the top. They look to be about 10mmx20mm. Newark

TLDR;

Me dumb, me never ordered relay before... Need one 24VDC dpdt signal relay for Marshall 9100 (does this work?) and one 6VDC dpdt Signal relay for Mystery Hiwatt Lead 50R. (Does THIS work?)

[The Dude]

You can usually find a part number and brand on the relay itself. If that's a no go, I'd go to Mouser and do a search using all known parameters to narrow it down- voltage, size, lead spacing, etc. Without part numbers, it will likely require looking at some data sheets.

[Enzo]

You need to know the coil voltage and current and the contact pattern and specs. Relays in the preamp are usually switching signals, so the current demands are tiny. Your signal path is not measured in amperes. Microamperes or milliamperes at most. You will likely see a category of small signal relays. The speaker relays at the output of some amps have to carry all the high current to the speaker. SO you want to look for contacts measured in multiple amperes.


Mouser or Newark or Digikey won't have the slightest idea what Marshall used or Hiwatt used in anything.

[Jon Snell]

If you read the ident number/letters on the relay, that will be the manufacturers part number and Mouser/Newark etc will list it or near equivalent.
The relay you have found is a Double Pole, Double Throw 24volt type and if the original calls for a 24volt coil relay, it will probably be OK.

I cannot help with the HiWatt as none of my service manual list a relay in use at all.
Must be a newer HiWatt, my manuals stop after 1990.

Maybe this will help to identify your relay;

[Mr_bibbles]

Thank you guys, this is very helpful, I really just needed to be sure I wasn't about to order like, a relay sized for a missile defense system on accident.

I cannot find ANY relays on ANY Hi-watt schematic, and this one looks like early nineties at the very latest. The relay itself does say "6VDC / 66 ohms" but the serial number / part number yields nothing. It has 8 lugs, so I assume "DPDT, 6V, 66 Ohms coil impedance"... Would this one from mouser work? I cannot find any information about coil impedance from the datasheet, how sensitive are amplifiers circuits In general?

[g1]

but the serial number / part number yields nothing.

Tell us what it is.

[Mr_bibbles]

Tell us what it is.

The case says "6VDC 66 (ohms)"

The other text is a RS Branded logo, with "p8509", under that "346-851" The only thing google tells us with that number is that it's a discontinued "MIN-D.I.L. 6VDC relay"

[tedmich]

I found an alternative RS Components PN that was 351-819 and that gives an equivalent part from TE


TE PN is V23105A5502A201 searching that may find you some stock, good luck! (check all the dimensions and pins also!)

here is a picture from RS Singapore

[Mr_bibbles]

I found an alternative RS Components PN that was 351-819 and that gives an equivalent part from TE


TE PN is V23105A5502A201 searching that may find you some stock, good luck! (check all the dimensions and pins also!)

My Hero! This is all very helpful for the future. This part is not available anymore, but I have a datasheet for comparison now and that's great! Thank you all very much for the free lesson on which parameters are most imporant!