Technics SL1100 / SL110 Fault

[thermionic]

Hi,

I’ve got a Technics SL1100 / 110 and it seems to start intermittently. It’ll start / stop indefinitely if you leave it in one place, but when you move it (after removing the platter) it won't re-start at all. When you put the platter down it seems to be a lottery as to whether it’ll work or not. Although I can use it and it keeps pitch fine, I can’t live without being able to move it.

I’ve attached the schematic. When it fails to start, it doesn’t move at all – it’s completely dead. It either works perfectly or not at all. I’ve tested all switches and polished connector pins / deoxit. It has new electrolytic caps. I can’t figure out if this is a mechanical fault or electronic. It’s not easy to get probes in there while the platter’s on.

Any tips gratefully received. Thanks in advance.

Justin

[Netlist]

Without schematic I think you should look for bad solderings. Components like power resistors and -transistors are the main suspects.

[thermionic]

Originally Posted by Netlist

Without schematic I think you should look for bad solderings. Components like power resistors and -transistors are the main suspects.

Sorry! I failed to attach the schematic. Please see edited post.

Power resistors? Do they go bad? I see bad caps every day, but this is a new one. I'll desolder them and measure with my LCR meter.

Can transistors go intermittent? In my experience they either work or they don't.

I'm really suspicious of the drive system here. Having said that, if the motor / feedback coil were a problem, it would do something, right?

Thanks.
J

[Netlist]

I meant the solder joints of power R's and transistors.

[thermionic]

Originally Posted by Netlist

I meant the solder joints of power R's and transistors.

You made it clear - I have been stressed today and probably wasn't comprehending you. I've reworked all the joints on PCB, and - what I believe *may* have been the culprit: stripped and re-soldered a lead to the motor - it was loose and felt as if it were going to snap...

J

[Netlist]

Keep us informed.

[makaiyumtony]

Originally Posted by thermionic

Hi,

I’ve got a Technics SL1100 / 110 and it seems to start intermittently. It’ll start / stop indefinitely if you leave it in one place, but when you move it (after removing the platter) it won't re-start at all. When you put the platter down it seems to be a lottery as to whether it’ll work or not. Although I can use it and it keeps pitch fine, I can’t live without being able to move it.

I’ve attached the schematic. When it fails to start, it doesn’t move at all – it’s completely dead. It either works perfectly or not at all. I’ve tested all switches and polished connector pins / deoxit. It has new electrolytic caps. I can’t figure out if this is a mechanical fault or electronic. It’s not easy to get probes in there while the platter’s on.

Any tips gratefully received. Thanks in advance.

Justin

Hi Justin
I bought my SL1100 at 1972, it had problem of speed stable before when pressed the switch for checking speed, the speed changed, also same by finger hit the body too, 5 years ago I did the modification, I took the whole power unit out into a separate box, connected to the motor with a extend cable, replaced the speed control with a precision potentiometer (10 turns) , if you doing in this way you can easily to check all the out put voltages, I also kock off the legs replaced by cones, make it thinner, now it work very stable and no more problems, but I only use it as a driving motor for my belt drive TT and have supper result
regard Tony Ma

[Sendy]

May be irregular defect inside component. Often problems in heat-stressed parts (power resistors, transistors, etc.).
I would solder a set of thin wires on the important points (GND, supply, oscillator, output stage) and measured on the complete device.