Siel DK600 - probably battery related but strange

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Siel DK600 - probably battery related but strange

Post by maadmardigan » Fri May 29, 2020 12:36 am

Hello. I have a opened up a non-working Siel DK600 and of course the dreaded battery failure happened. However someone definitely attempted to work on it prior to me and the battery has been taken out and half the screws to hold the boards are missing but nothing else seems to have been futzed with. I have cleaned it up and replaced the battery and have gotten it partly working. However, some issues rendering it unusable persist.

1) You can hear the voices but VERY faintly underneath a wall of noise
2) None of the potentiometers, aside from Master Tune and Volume, have any effect. However, all the switches seem to be working as expected.

I've checked out the two 4051 mux ICs on the left control board and they seem to be fine though I'm unsure of whether they are supposed to be outputting the analog control voltage from each of the pots via pin3 (common out) or is it converted into some binary and output via the A/B/C outputs?

With the assumption that the MUXes are working but the failure is happening on the digital board near where the battery exploded, where should I be looking? I have poured over the schematics looking for the other side of the Vrd from the control board and can't for the life of me find it. I have had a hard time tracing the lead from the ribbon connector because it hops between the sides of the board and seems to disappear underneath resistors on the component side. Does anyone know where the output from the MUXes for the pots goes after it crosses to the digital board?

Would the lack of voltage control lead to the noise generator being at max at all times?

Any help in advance is appreciated!

Thank you!

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