Hi all, to avoid dobble posting, im hoping that some of you experts could look into my thread here on the same problems, and give me an hint ?
Thanks
http://www.diyaudio.com/forums/analogue-source/189999-technics-1210-speed-problem.html
Thanks
http://www.diyaudio.com/forums/analogue-source/189999-technics-1210-speed-problem.html
Problem solved replaced AN6680
Had the same erratic speed problem with a 1200mk2 from new. Never had it repaired under warranty as I was out living and working in the middle of nowhere. The problem in the early days would only start after the turntable was in operation for over thirty mins or the weather was hot. A nuff nuff at the $100 an hour dj city service in Melbourne told me it would almost definitely be the pitch slider - but after swapping pitch slider myself with working unit I confirmed this was not the issue. After reading on this forum that mnsh from Gothenburg and dgb from Auckland had fixed this issue by replacing IC201 I ordered one of these panasonic AN6680 chips through Amazon.com for something like $35USD delivered to Melbourne, if I recall properly. Now after replacing the chip and some rigorous testing, my turntable works perfectly for the first time in its life.
Had the same erratic speed problem with a 1200mk2 from new. Never had it repaired under warranty as I was out living and working in the middle of nowhere. The problem in the early days would only start after the turntable was in operation for over thirty mins or the weather was hot. A nuff nuff at the $100 an hour dj city service in Melbourne told me it would almost definitely be the pitch slider - but after swapping pitch slider myself with working unit I confirmed this was not the issue. After reading on this forum that mnsh from Gothenburg and dgb from Auckland had fixed this issue by replacing IC201 I ordered one of these panasonic AN6680 chips through Amazon.com for something like $35USD delivered to Melbourne, if I recall properly. Now after replacing the chip and some rigorous testing, my turntable works perfectly for the first time in its life.
Service manual trouble shooting states, if speed changeover is defective check or replace IC201, S201,S202, D201,D202. IC201 is a AN6680. D201 and 202 are the LEDs they are ok they either light or they don't. I would suspect the AN6680 and replace it and see what happens. Sounds like you already swapped out the speed switches S201 and S202, but you may want to shoot some contact cleaner into them B/4 you do anything else, since they were out of another table they may be dirty and they may be causing the problem. GOOD LUCK
For any erratic speed problems on warm-up, with pitch off-center, (symptoms first visible with pitch at -8%) it is definitely worth replacing D301 before ordering the AN6680 or AN6682 IC's.
I would recommend 1N5231B for replacement as it has a sharp zener knee and good temperature coefficient.
I would recommend 1N5231B for replacement as it has a sharp zener knee and good temperature coefficient.
Quick update,
I had 2 in for repair with the same problem, the second was fussier, looking trough the service manual on various schematics you can either read 2k7 or 10k for R307.
The turntables I have are from 2006 and had 2k7 for R307, replacing this by 10k solves the problem much better than finding a good 5.1V zener for D301 as this turntable would loose lock with voltages of 5.3V on D301.
With 10k the fall time and low-level noise of "FO" (Pin1 of IC301/IC302 or pin3 of IC201) are much better.
The odd thing is that with a trimpot in place of R307 I find that 2.7k ohms is about the value needed for problems to appear, maybe Matsushita decided their product was much too reliable for the present day and found a quick workaround for making it less reliable with minimum modification. Maybe not, but then someone will have to explain why R307 should be 2.7k
Can someone with a much older SL-1200mk2 confirm the value of R307?
I had 2 in for repair with the same problem, the second was fussier, looking trough the service manual on various schematics you can either read 2k7 or 10k for R307.
The turntables I have are from 2006 and had 2k7 for R307, replacing this by 10k solves the problem much better than finding a good 5.1V zener for D301 as this turntable would loose lock with voltages of 5.3V on D301.
With 10k the fall time and low-level noise of "FO" (Pin1 of IC301/IC302 or pin3 of IC201) are much better.
The odd thing is that with a trimpot in place of R307 I find that 2.7k ohms is about the value needed for problems to appear, maybe Matsushita decided their product was much too reliable for the present day and found a quick workaround for making it less reliable with minimum modification. Maybe not, but then someone will have to explain why R307 should be 2.7k
Can someone with a much older SL-1200mk2 confirm the value of R307?
Here's the comparison.
Another thought is that maybe the output driver on pin3 in the AN6680 goes faulty then changing R307 comes as a solution but IC201 could be the real cause, I have none at hand to check.
An externally hosted image should be here but it was not working when we last tested it.
Another thought is that maybe the output driver on pin3 in the AN6680 goes faulty then changing R307 comes as a solution but IC201 could be the real cause, I have none at hand to check.
Yeah, I signed up just for that purpose.
After messing around for a few hours (heating up the pcb to approx. 40-50°C, below the problem never occured) and measuring around i nearly gave up and blamed the AN6680. This was horrible, because I needed the 1210 at this weekend. After you mentioned the different values of R301 I thought I'll give it a try - and it worked perfect. I'll keep a spare 10k resistor near my second 1210 if it ever suffers the same problem...
Thanks again, this really saved my weekend.