Roland spa-240 tripping.

[Omnialinx]

Greetings
So I have this Roland spa-240 I would like to use. I build and design recording equipment bit repair amps too. I can't figure out why this trips whenever it turns on.
I have the schematic but can't figure out where to look. It seems they designed later on a protection circuit that they implemented in later versions. I've read of people modifying them but at this time I ust want it to work. Apparently the schematic is too big to attach here. Has anyone worked on these and or had the same issue?
Below is a link to the schematic:
http://bee.mif.pg.gda.pl/ciasteczkowypotwor/SM_scena/Roland/Roland%20SPA-240%20Power%20Amp%20Service%20Manual.pdf


Thanks in advance

 

[JonSnell Electronic]

Could be a high DC off set, check C4 and C104.

 

[JMFahey]

Turn amp ON, without a speaker load, and measure for DC voltage across each channel speaker out terminals.

Any significant DC there , say >2V or so, will trigger speaker protection and relay will switch speaker OFF

Even better, since if DC present those terminals will be switched OFF , measure DC from the large 0.3 ohm 5W emitter resistors to ground.

Designation varies according to version, but in the first schematic they are R29/30/31/32 , the track joining them is the amplifier channel speaker out.

 

[Omnialinx]

Great stuff. Thank you. I'll check those areas and report back

 

[Omnialinx]

I found the problem while testing R30 the .3 5watt. I feel ridiculous that I didn't see this before.
So I have some bewildering to do.

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[Omnialinx]

And to add it was the c104 area. Thanks gents.

 

[Omnialinx]

Ah man. So I am having a hard time finding 2sc2238/2sc5171 replacements at mouser, digikey etc... Anyone know of a good source?