Replace main relay in Amp

[techfixit]

Hi, I have an unknown brand amp that when i first power on the main relay keeps clicking for about a minute or so afterwards. I've checked all solder points and everything seems to be in order so i'm left with the relay itself.

I'd like to replace it but the relay in question is no longer in production. Can someone suggest a replacement for an OMI-SS-212DM? I'd prefer to purchase it from an irish or uk seller if possible

Thanks in advance

[R_J]

Re: Replace main relay in Amp

It sound more likely that the supply voltage for the relay is low causing the relay to droping out. or maybe a low standby voltage causing the drive to turn on and off

[petehall347]

Re: Replace main relay in Amp

sounds like a bad relay driver to me . or bad timing cap if it has one . or possibly ac riding on the dc supply .
need to see good pics and schematic to proceed further .

[keeney123]

Re: Replace main relay in Amp

Perhaps this is the same relay https://wellgainelectronics.com/pcb-...-ss-212dm.html

[techfixit]

Re: Replace main relay in Amp

I'll post some pics of the front/back of the board tomorrow. The relay only acts funny for about 10-30 seconds after powering on the amp then it works perfectly fine until the power is switched off and back on again.

[techfixit]

Re: Replace main relay in Amp

I've attached some pictures of the board. I tested the 3 diodes close to the relay in diode mode and the results show

1: .527 leads reversed 0
2: .527 leads reversed 0
3: .140 leads reversed .140

Could a bad diode be the cause of my problem?

[keeney123]

Re: Replace main relay in Amp

Either the relay contacts are going bad or the voltage that is on the coil is fluctuating at start up. Once you find out what the voltage is doing on the coil of the relay is doing at start up you will know which one to investigate.

[budm]

Re: Replace main relay in Amp

That is speakers protection relay.
The two caps (220uF/25v, 47uF/25v) and and the 3 transistors and diodes right below the relay as shown in your pictures are probably for the DC detection/relay drive circuit.
So you the circuit may have detect DC at the output of the amplifier or there is bad parts such as those two caps are bad.
Make and model of the unit?

[petehall347]

Re: Replace main relay in Amp

monitor the dc voltages where the emitter resistors join together whilst relay is playing up .
emitter resistors are the big white ones next to the output transistors .

[techfixit]

Re: Replace main relay in Amp

On budm's advice i tested the 2 diodes and 3 transistors near the relay. I discovered that the 47uF/25v capacitor was showing no value in either direction when i tested it with my esr meter. I replaced that diode and now the relay is switching perfectly without any issue

[petehall347]

Re: Replace main relay in Amp

might have been the timing cap .. hard to say without diagram ..
well done fixing it ..

[keeney123]

Re: Replace main relay in Amp

On budm's advice i tested the 2 diodes and 3 transistors near the relay. I discovered that the 47uF/25v diode was showing no value in either direction when i tested it with my esr meter. I replaced that diode and now the relay is switching perfectly without any issue

So the 47uF/25V is a capacitor not a diode. A esr meter is for capacitors.


Glad you got it fixed.

[budm]

Re: Replace main relay in Amp

Thanks for the follow-up on the repair.
Make and model of the unit?

[techfixit]

Re: Replace main relay in Amp

So the 47uF/25V is a capacitor not a diode. A esr meter is for capacitors.


Glad you got it fixed.

Apologies i meant Capacitor

[techfixit]

Re: Replace main relay in Amp

Thanks for the follow-up on the repair.
Make and model of the unit?

Promethean AV-30164

[keeney123]

Re: Replace main relay in Amp

Apologies i meant Capacitor

No problem just wanted to make sure you understood.