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Technics SL-D5 Turntable - - Runaway Speed issue

redpackman

redpackman

Active Member
I just picked up a really nice, clean SL-D5 turntable, with BOTH spindles. This has been taken care of well, It looks like it's worth the effort. Dust cover is in good condition, clean etc. etc. I was excited, but the seller warned me that there was a speed control issue. I thought, no problem. I've cleaned the speed control pot(s) on these many times with De-oxit. A little spray and we're off and running. I just got an SL-D2 going great about a week ago with that approach.

Not so with this one. The speed control got sprayed. I tried to adjust the 33 and 45 rpm pots on the circuit board as I know they have a significant effect. Nothing works.

There turntable just runs faster and faster. Out of control on both 33 and 45. Adjusting the speed selector changes nothing, adjusting the externally adjustable fine tuning pot does nothing. Adjusting the pots on the board have minimal effect but don't bring the speed down to 33 or 45 rpm.

The boards on this look just like the one on the SL-D2 (a schematic of which is available on Vinylengine), the major difference being the automatic changer mechanism, which I hope I don't screw up if I have to work on the PC board, disassembling the unit to get to the board.

I've heard that bad caps can do this. How about one or more of the transistors, or, heaven forbid, the chip on the board?

Suggestions welcome.
 
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Look for a fault associated with the tach coil connections on the motor circuit board, and associated circuits.
 
"Look for a fault associated with the tach coil connections on the motor circuit board, and associated circuits."

thank you for the tip!! Do you mean to re-flow the solder connections, or is it more complicated than that?

Which connections around the motor are the "tach coil" connections?
 
redpackman said:
"Look for a fault associated with the tach coil connections on the motor circuit board, and associated circuits."

thank you for the tip!! Do you mean to re-flow the solder connections, or is it more complicated than that?

Which connections around the motor are the "tach coil" connections?
Click to expand...
These planar motors usually have a wavy or block-y circular trace on the board under the rotor magnet rim, that would be the tach coil. Follow traces from it.
 
redpackman said:
I just picked up a really nice, clean SL-D5 turntable, with BOTH spindles. This has been taken care of well, It looks like it's worth the effort. Dust cover is in good condition, clean etc. etc. I was excited, but the seller warned me that there was a speed control issue. I thought, no problem. I've cleaned the speed control pot(s) on these many times with De-oxit. A little spray and we're off and running. I just got an SL-D2 going great about a week ago with that approach.

Not so with this one. The speed control got sprayed. I tried to adjust the 33 and 45 rpm pots on the circuit board as I know they have a significant effect. Nothing works.

There turntable just runs faster and faster. Out of control on both 33 and 45. Adjusting the speed selector changes nothing, adjusting the externally adjustable fine tuning pot does nothing. Adjusting the pots on the board have minimal effect but don't bring the speed down to 33 or 45 rpm.

The boards on this look just like the one on the SL-D2 (a schematic of which is available on Vinylengine), the major difference being the automatic changer mechanism, which I hope I don't screw up if I have to work on the PC board, disassembling the unit to get to the board.

I've heard that bad caps can do this. How about one or more of the transistors, or, heaven forbid, the chip on the board?

Suggestions welcome.
Click to expand...
@redpackman
hi
did you solve it at the end?
having the same issue with SL-D2
 
I had an issue like this with a Technics (don't remember the model) I solved it by replacing the variable speed resistors.
 
stratokaster said:
check the solder joints in the areas circled in red

View attachment 2085712
Click to expand...
Thanks a lot!!

Seems like it solved my issue of accelerating to high speed.

Now i see i have another issue with the speed.
It sometimes going faster a bit, stay the same, then goes back to normal speed or a bit lower.

I already deoxit all pots, and reflow many many solder points.
 
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