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VPI SDS 45 RPM malfunction

I have a brand new SDS unit that I've used for about a month now and it's been working fine at 33 rpm, but last weekend I tried to put on a 45 rpm record and the unit malfunctioned. I was able to adjust the frequency up to 80.80 Hz, which the strobe indicated resulted in correct speed, but the voltage would flicker between 72 and 115 V for several seconds and settle at 72. It seemed the turntable was holding speed at 72, but when I put the record on and the periphery ring, the SDS kept going back and forth in frequency between 33 and 45 (up and down between approx. 60 to 80 Hz and the motor would audibly "slip" when the SDS got to 80.80 Hz and then started going back down).

Is this a matter of adjusting the unit or is the unit broken? I sent an email to VPI, but I know they are very busy so I thought in the meantime I'd ask here. Any ideas or suggestions?
actusreus
actusreus OP
733 posts
 
Thanks Brf. What's strange is that I had an SDS unit before, and it worked fine with that same turntable at both speeds. Never had a problem or had to adjust settings.
brf
1,715 posts
 
Try stepping up the SDS run voltage from 72v to something higher. I would start at 75v and increase the voltage until the voltage stops varying between the run and startup voltage.
actusreus OP
733 posts
 
If I remember correctly, the run voltage was higher for 45 RPM, but it would adjust itself automatically once you switch from 33 to 45. Also, I'm not quite sure how to adjust voltage since it comes pre-calibrated from the factory.
philb7777
401 posts
 
definitely sounds like a malfunction of the SDS. I don't currently own one, but did for several years and it shouldn't be acting like this. Your voltage should set automatically based on the speed / Hz yoy dial in. For it to fluctuate means an internal problem only VPI is likely to fix.
brf
1,715 posts
 
Go to VPI's website and download the SDS calibration manual. In the manual are detailed instruction on how to adjust the SDS "steady state" voltage (run mode). For 45rpm, the factory default should be either 90 or 102 depending on the software version. If your SDS is dropping from 115v to 72 v after startup when in the 45rpm setting, it needs to be adjusted higher. You cannot hurt your table by trying a higher steady state voltage. I hope this corrects your problem
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