SL-1500, speed fluctuates

Read more on the Technics SL-1500 in our home audio section

Bodi Satvva2004-02-29 04:08

Technics SL-1500. I use to clean the disc using the discwasher brush. Now my speed fluctuates. Changed the rheostat but that did not solve the problem. Do you have and opinion?


Gherardo Casale2004-02-29 04:08

I recently buyed a Technics SL-1500 for 45$. It had your same problem: the speed fluctuated. Like Kai suggested, I removed the case bottom and I used a deoxidant electronic spray for washing the pitch potentiometres and the 33/45 on-off switch. Then I lubrificated the main bearing (the bearing under the centre of platter). Now my SL-1500 simply works fine. Best regards, Gherardo Casale

Bob Scarborough2004-02-29 04:09

The SL-1500, as well as the auto and semi-auto variants, all had this problem due to noisy pots in the motor current regulation circuit. I\'ve never seen the ”circuit go bad” on one of these, and I\'ve worked on probably 50. The cure is to simply ”exercise” the speed adjust pots, both on the top panel and the range pots found under the platter. At the same time, be sure the power switch is also clean and not introducing spurious resistance into the circuit. Any Japanese electronic gear of this era will show signs of dirty/oxidized switches, pots and failed contacts due to a shortage of phosphor bronze in Japan about this time. All Japanese cars from that era as similarly affected, with Hondas and Datsuns with Nippondenso electrical gear being about the worst.

Once the contact is cleaned using the normal solvents and treated with ”pot grease”, you\'ll get good service again for a year or so, when the treatment will have to be given again. Although this problem is notorious on the SL-1500 and cousins, the SP-10, SL-1100 and the overrated SL-1200s all had the same problem. However, due to higher current in the control circuit, the chance of a ”dirty” pot or switch causing this problem is far less than in the lower current/lower torque SL-1500. SL-1500s were disparaged by the DJ crowd in the \'70s for their low torque and low speed ramp-up, which caused problems when ”beat mixing”, popular back then. They also have an overspeed problem when settling into speed, which causes a noticeable pitch wow from a half to three-quarters of a turn after start, something the SP-10/SL-1100/SL-1200 did not have. For a home direct drive unit, the SL-1500 will perform as well as any of the Technics line in terms of wow and flutter, once you clean the pots and switches! The lightweight platter has been disparaged by ”audiophools” for inducing ”ringing” into the disc, something which has never been proven or even alluded to scientifically. The arm, of course, is disposable; mine has an SME 3009 Mk II with the nice cast aluminum replacement plate marketed by Panasonic back in the \'70s. Once you get a good arm on this table (or any of them), it\'ll perform as well as any table with the same arm. Technics arms are, for the most part, cheap high mass garbage suitable only for $6 Stantons and Grados. Bob Scarborough

D.h. Paul2004-02-29 04:09

Hi, The Technics SL-1500 is notorious for having this problem. Most of the Technics direct drives will hold their speed over the years, but the 1500 often does not. It is possible that the pots are dirty and causing this as one guy answered here, as this often happens with the turntables with pitch control (you should always clean the pitch pots on a used turntable), but in the case of the 1500, it is probably the circuit and not worth trying to fix. I know it is sad to hear, but you should
probably lay it to rest. I would keep it as a parts unit if it is in nice shape, in case you find, in your search for a new tt, a Technics w/ a missing headshell, counter weight, or dustcover, etc.

Don\'t go seeking another 1500, for it will likely develop the same problem if it doesn\'t have it already. The SL-D2 from Technics is very reliable and affordable. I\'ve bought and sold many of these and they are built very solid and will last forever, and are just as good sounding as the rest of them. You can get one fairly cheaply on ebay or elsewhere.

Kai2004-02-29 04:09

Hello, I own a SL-1500, and I had this problem, too. It was the speed control knobs that did not function correctly because of aging. Try the following: lock the tone arm, carefully remove the platter. Now remove the two speed knobs by pushing them (could be tight, but don\'t worry), turn around the TT and remove the case bottom. Now you remove the little plate that is holding the speed control potentiometers. Use electronic-cleaner Spray to wash the pots. Afterdrying you can use fine oil (weapon-oil is good) to seal the potis and have a smooth operating feel. You can do the same with the 33/45 on-off-Switch, this one also tends to make trouble over the years. Now
your tt will function fine again. regards, Kai

Danj2004-02-29 04:10

I suspect that using the Discwasher has nothing to do with the speed fluctuations on the SL-1500. I suspect there is a circuit problem with the speed control circuit board. With shop rates and parts being as expensive as they are, the fix is probably more expensive than the turntable is worth - that is, the turntable can be replaced with a good used one cheaper than a broken one can be repaired.

This is the most common problem I have seen with older Technics turntables. The good news is that the brand is very reliable and common so replacements are inexpensive (at least in North America).

Rsir2012-05-17 15:51

Technics SL 1500. Bought in 1975. Played on a daily basis untill 1985. (my CD-player became more popular)
Speed problem started 2 years ago.
I cleaned with acetone the 4 potmeters dealing with speed and lubricated them with WD40.
Since then the (still) small variation in speed is tolerable. I did nothing with the 33-off-45 switch

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