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BIC 1000 need Help

Hi Doug, I put the circuit board under my magnifier tonight and check all the solder joints, they are all looking good. I put it back again, this time I remove the motor out of the chasis and tried to wiggle and see if it moves, nothing happened. But when I touch the circuit board again, the heat sink cover the IC is very hot ... indication of the bad IC. I look at the pinouts look like it is a 7x2 pins IC and the 3 pins in the middle tied together on both sides. I search for a equivalent Op Amp IC and comes up with this TI LF347 https://www.ti.com/lit/ds/symlink/l...29029&ref_url=https%3A%2F%2Fwww.mouser.com%2F and it's a quad model with 4 channels, 4 amplifiers. And according to the schematics in the services manual, all pins 3,4,5 and 10,11,12 are all tied together and negative ... :-) ... Anyhow, I think you are right, somehow the IC is overheated and failed. I will wait for Adam's email another day then I just go to ebay and order an IC from him to try out ... This is fun but my wife is complaining ... Oh well, what else can we do during this pandemic lock down!!! Thanks again for sharing the knowledge. Regards, Quang
 
OK, good progress. If you power up the board without the motor connected, does the IC still get very hot? It's still possible the motor is bad and loading the IC too much.

You could disassemble the motor, just remove the bottom cover, it's just stuck on there with self adhesive, and look at the coils for burning or other damage. It's probably unlikely it's the motor but you never know.

Doug
 
Hi Doug, this is what I have done so far.
1. Took out the motor. Visual inspection of the coils, coil is wrapped with white plastics and nothing unusual can be seen. Check all the input cables, looking good.
2. Put the motor to a drill, turned the motor using the drill, measured all outputs, one side give me a 6VAC, the other give me about 10.6 VAC ... should they be the same? or one coil got shorted and give me double the voltage?
3. Put everything together, the temperature at the heat sink is about 3-5 time hotter when connected to the motor. Pin 4&6 is now 1.8 Volts and Pin 5&7 is now at 3.8 volts .. very strange...

I have emailed Adam and ask to order the LM377 IC but at this point, I am leaning toward a fail motor (Coils).
Should I look for another motor now?

Thanks,
 
I worked in the service department for a large retail chain that sold BIC tables. When ever one of the electronic models came in with motor control problems it was almost automatic to replace the control board. I never saw one with a motor that had electrical issues, just mechanical, the shaft would separate from the magnet and free spin... the fix was to disassemble, clean, reassemble with a dab of super glue to secure the shaft to the magnet, never had one come back. In 'our' opinion the 960 was the preferred model, same as the 980 but without the servo control and it's problems... pretty much trouble free except tended to lose the cue damping fluid and sometimes the end of record trip mechanism would need to be cleaned... required removing the cam.
 
Measure the resistance of the two motor coils. They each should be the same and about 8.5 ohms. If they aren't, the motor is electrically bad.

And yes, if you spin the motor with a drill, the voltage output from each coil should be the same.

Doug
 
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