Need a couple hints for bypassing Relays in a Roland DEP-5

[crochambeau]

does the unit have a broken 12v regulator? or was it just running 5v to the relays?

Could have been a 12 volt regulator, no voltage to the relays. I did not spend the time sniffing around on it.

This unit has been beat to shit, and it's a noise friend deal (we're talking no budget territory here, and the pops on power are not a big issue) so an expedited "half assed" fix was acceptable. The unit in question does not even have a power switch, so power cycle sequencing is sort of built in.

[Psyre]

So by 4, you mean duplicate the process on both relay locations, correct? Also what do you mean by making sure to supply 12v? Just want to be extra clear before I attempt.

[Psyre]

Is there a way to bypass and leave the bad relays in? May save the traces that way 8 )

[crochambeau]

So by 4, you mean duplicate the process on both relay locations, correct? Also what do you mean by making sure to supply 12v? Just want to be extra clear before I attempt.

Yeah, both relay locations. One relay does right channel (input and output) other does left.

The 12 volts should be supplied by the Roland. It will be appear across the legs I circled in red. I have no idea as to what polarity, presumably if it is there it is correct. I'm guessing since the power switch has been lost on this unit for a very long time, it has seen some hours powered. I find it very feasible that the 12 volt supply gave up, it does not appear to have affected anything else.

I'm sure you can cut & jump without messing with the relays. I can upload the uncropped & untouched photos of that area if it will assist in direction to do the cut & jump. Of course, then you are intentionally cutting the traces..

[eatyourguitar]

I have the schematic and PCB traces here

http://www.synfo.nl/servicemanuals/Rola ... _NOTES.pdf

the relay coils are stacked and powered by a PNP connected from +15 to -15v. this puts the voltage drop across each coil at about 14v close enough to 12v.

with the unit on you can check the logic output of the MCU with the probes on pin 36 Vss (ground 0v) and pin 19 relay controller logic. toggle the bypass switch and probe again. pictures of pinouts on the IC 8097 are all there in the service manual. if you have working logic and working transistors then maybe just fix it right with new relays.