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Technics SL-1900 speed control

hammr7

hammr7

AK Subscriber
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I cleaned up a Technics SL-1900 I had as a Christmas present for my son, who wanted to get into vinyl. Everything seemed to be working perfectly until he purchased his first 45 RPM record.

My problem is that, while the 33 RPM speed is fine (and can easily be adjusted higher or lower with the pitch control), the 45 RPM speed is much too fast. Adjusting the pitch control as low as possible results in a speed that is higher than 45 RPM. Before I start ripping the unit apart, has anyone ever dealt with - and corrected this problem? I expect the setup of this unit is likely the same as many other Technics direct drive units of the period.
 
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On several direct drive turntables (Technics included) I had to spray Deoxit in the pitch control to fix speed instability. Not sure if this will fix your issue of it running too fast, but it's a good start.
 
SSaxdude said:
On several direct drive turntables (Technics included) I had to spray Deoxit in the pitch control to fix speed instability. Not sure if this will fix your issue of it running too fast, but it's a good start.
Click to expand...

This is always the place to begin. On the SL-1900 there are two different pairs of speed controls. One pair you already know about, the two potentiometers you've already tried to adjust. There is also a pair of variable resistors inside the turntable soldered to one of the circuit boards. Partial disassembly is necessary to access both pairs. It has been years since I've been inside one of these but I don't recall that the disassembly was particularly difficult or extensive.
 
Thanks for the replies. I will see my son this weekend and try the obvious pitch control cleaning. If that doesn't work I'll figure where the internal adjustment is at. I'm hoping for the 5 minute fix rather than a weekend project.
 
hammr7 said:
Thanks for the replies. I will see my son this weekend and try the obvious pitch control cleaning. If that doesn't work I'll figure where the internal adjustment is at. I'm hoping for the 5 minute fix rather than a weekend project.
Click to expand...

It's really not that hard. Usually 15-30 minutes if you have a couple of screwdrivers and the contact cleaner handy. If you are opening it up to clean the visible controls, you might as well do all 4 controls. You really have to open it up to properly clean even the visible controls because you are just looking at the knobs.

A tip or too:

Do the little ones on the board one at a time and try to remember where approximately the slot points when you start. End up after cleaning with it pointing the same way. Do the other one the same way and also both of the larger controls.

With luck the external controls will now have a range up and down from 33 and 45. If they don't, turn the large pots to the middle of their range and then fine tune the little ones until the speed is correct on each speed. Button it back up and the external controls should have a good amount of range both up and down.

All 4 controls are very close together and on the same circuit board. There's a good picture in this thread at VE: http://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=70593
 
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