Hi everyone. I have a Technics SL-1700 turntable (1977). It was not used for about 10 years. It has developed a speed stability fault where the turntable is very slow to stabilise and will overshoot badly if the turntable is loaded to slow it below the normal speed (both 33 and 45 RPM) . I suspected corrosion on the pots (4of them) or something wrong with the speed selector switch. Unfortunately after extensive cleaning of the parts and checking their working with a meter the fault is still there. I have also cleaned and checked the multiway connection of the multi-wires from the PCB to motor assembly...nothing wrong here. I have now replaced every electrolytic capacitor but it made no difference. I have the manual and the circuit is pretty simple. Before I replace all the resistors and film capacitors, I wondered if there is anyone reading this who might have solved the problem please? It really is so depressing and time wasting to remove and replace good components for nothing. Summing up the fault I would say it caused by a slow or weak speed feedback as the motor has full power on start up and will eventually stabilise over a minute or two if the load level is not changed on the platter....Bench testing is slightly tricky as I would imagine the motor needs to be connected to the PCB before voltage checks are made but if necessary I can strip the entire parts out to do this, before binning it. Thanks in advance...🙁
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Hi bedrock6202...Will do, but for now, I've given up as I reckon the big LS chip has a defect (unobtainable). It seems 95% of the time it is simply the speed adjustment pots that need cleaning or the speed change switch. In fact that might have been the case with my one because I cleaned those items first but stupidly switched on the turntable before I had refitted the platter this might have somehow blown something in the chip. The fault is now permanent it seems. I'm looking out for a bashed up turntable that still has the driver board intact to swap over. ...Anyone out there got one please? 🙂