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TonyDuell · 24th Dec 2017, 6:43 pm

I have now traced out the circuit diagrams (by hand, I don't use a CAD program) for all the PCBs and can confirm that the amplifier is very different to the one in the manual. In many ways it's better, using transistor switches rather than mechanical contacts and with a (hopefully) better equalisation network.

I am now restoring the machine (Mods : if this should be a separate thread I can start one, but it is the same machine). I've fitted a new belt kit and got the mechanism back togehter. Taken everything apart that will sensibly come apart and cleaned it, cleaned the heads and demagnetised them, etc. Now working on the electronics, I've got the base board back in place and after fitting the Drive Control PCB it seems as though the mechanical side works. I can select the direction, the pinch rollers engage, etc. I'll look at the audio side of things in the future.

A few tips for anyone working on one of these machines :

Download the user manual as well as the service manual. The former contains wiring diagrams for many of the adapter cables.

Make up a cable with an 8 pin offset DIN plug on one end and plugs to fit your bench supply on the other (the car power cable diagram in the user manual shows which pins to use). Run the machine off your bench supply. The current limit on that will protect things if you do something silly before any damage is done.

The internal wiring is fragile. Some of the wires are solid core, and almost all are brittle. Wires drop off if you look at them wrongly. Expect to have to resolder things.

If a pinch solenoid appears to pull in and then releases after a couple of seconds, the most likely cause is that it's not pulling in far enough. The solenoid has 2 windings, one (high current) to pull in (controlled by the transistors and capacitors on the Magnet Control PCB, the one on the top side of the drive chassis), the other to hold the armature in. If the armature doesn't come in contact with the core end, then the latter will not hold it, so the solenoid will release when the high current winding is turned off. Check the mechanical adjustment of the clutches and operating levers.

24th Dec 2017, 6:43 pm	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Uher CR210 versions I have now traced out the circuit diagrams (by hand, I don't use a CAD program) for all the PCBs and can confirm that the amplifier is very different to the one in the manual. In many ways it's better, using transistor switches rather than mechanical contacts and with a (hopefully) better equalisation network. I am now restoring the machine (Mods : if this should be a separate thread I can start one, but it is the same machine). I've fitted a new belt kit and got the mechanism back togehter. Taken everything apart that will sensibly come apart and cleaned it, cleaned the heads and demagnetised them, etc. Now working on the electronics, I've got the base board back in place and after fitting the Drive Control PCB it seems as though the mechanical side works. I can select the direction, the pinch rollers engage, etc. I'll look at the audio side of things in the future. A few tips for anyone working on one of these machines : Download the user manual as well as the service manual. The former contains wiring diagrams for many of the adapter cables. Make up a cable with an 8 pin offset DIN plug on one end and plugs to fit your bench supply on the other (the car power cable diagram in the user manual shows which pins to use). Run the machine off your bench supply. The current limit on that will protect things if you do something silly before any damage is done. The internal wiring is fragile. Some of the wires are solid core, and almost all are brittle. Wires drop off if you look at them wrongly. Expect to have to resolder things. If a pinch solenoid appears to pull in and then releases after a couple of seconds, the most likely cause is that it's not pulling in far enough. The solenoid has 2 windings, one (high current) to pull in (controlled by the transistors and capacitors on the Magnet Control PCB, the one on the top side of the drive chassis), the other to hold the armature in. If the armature doesn't come in contact with the core end, then the latter will not hold it, so the solenoid will release when the high current winding is turned off. Check the mechanical adjustment of the clutches and operating levers.