This was purchased at a hamfest here recently, and the guy had mentioned they came from a repair shop in various states of disrepair. There is no tag on what the issue was, but you can clearly see someone had been inside trying to get the motor going.
They replaced the caps and transistor on the regulator PCB.
However the motor appears to be untouched and untampered with.
Anyone familiar with repairing these motors? What happens is when you first start it, it takes off although its erratic. it runs for about 3 to 5 seconds and stalls, wobbling back and forth between poles.
So I am wondering maybe noisy/bad transistor in the motor? caps? The service manual has no schematic on the motor so that is of no help.
I have never worked on one of these motors before so I am unsure. Also the speed switch and adjustments have no effect.
any ideas?
They replaced the caps and transistor on the regulator PCB.
However the motor appears to be untouched and untampered with.
Anyone familiar with repairing these motors? What happens is when you first start it, it takes off although its erratic. it runs for about 3 to 5 seconds and stalls, wobbling back and forth between poles.
So I am wondering maybe noisy/bad transistor in the motor? caps? The service manual has no schematic on the motor so that is of no help.
I have never worked on one of these motors before so I am unsure. Also the speed switch and adjustments have no effect.
any ideas?
I think I figured it out.
One of the driver transistors for the 3 poles is leaky. I can see it when I use a scope looking at both the AC and DC component.
However if I remove it from circuit, it tests "ok" on my DMM.
Leaving it out of circuit, the turntable runs without stalling, just a little jerky from the missing pole now.
So I think I am close.
One of the driver transistors for the 3 poles is leaky. I can see it when I use a scope looking at both the AC and DC component.
However if I remove it from circuit, it tests "ok" on my DMM.
Leaving it out of circuit, the turntable runs without stalling, just a little jerky from the missing pole now.
So I think I am close.
Exactly what it was. Tests great on DMM, but fails miserably under load.
Swapped it out with a 2N2907 or something along those lines, I forget. She took right off and is running perfect although she is a slightly bit drift happy. I guess because its not really quartz locked like the newer ones.
Swapped it out with a 2N2907 or something along those lines, I forget. She took right off and is running perfect although she is a slightly bit drift happy. I guess because its not really quartz locked like the newer ones.
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