Marantz 6300 problem (slightly different original pcb)

[david winter]

Hi,

In auto mode, pressing Down should release the electromagnet, but sometimes it immediately re-activates again.
I need to press Down several times until it stays released.
I checked all microswitches and they register up to 0.05 ohms on each section.
The pcb has been recaped a few years ago.
Zener diode H804 has correct voltage. Both rectifiers seem ok (DC voltages ok).
2SD331 transistor tests ok with my DCA75 (Hfe=82).
I thought about the thyristor but a new one didn't solve the issue.

Any clues ?

I noticed several differences between my turntable and the one shown in this thread :
- J810 (connected to J811) not present in my case.
- R806 is a 820 ohms in my case (1K in the other and on later 1976 schematic).
- Blue tantalum capacitor C003 originally soldered behind the IR sensor moved onto the pcb as C808 (shown on 1976 schematic).
- Light blue electrolytic C807 between J814 and J818 of other version moved onto the pcb.

I suppose that my version is the latest.
Also, there's a diode that looks like a 1W zener between J811 and J812. It's not shown on both schematics. What type is it ?

Thanks !