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Technics SL-1700Mk2 works intermittently ...

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douglasman

New Member
I have a Technics SL-1700mk2 under gone DIY repair. I've been search the internet for solutions to fix the STOP, AUTO Return, Cue functions. Following the diagram from the service manual, I've thought to have diagnosed the issue that IC460 (4013 CMOS) was the reason that the arm functions were inoperative. After I replaced that IC, I was able to see the auto/stop functions to work but only that it's failed again. When it fail, cue, stop , nor auto (end of play) have any response. The led's do light up when power on. What's interesting is that if I leave the unit off a day or two, power it on , every function would work once and than dies. Some how the behavior seems to be 'capacitor like' . It acts as if a capacitor needs a day of power off to completely drain to then be charged up when power on to work and then once it's charged, nothing works anymore.

Does anyone here have any clue ?
 
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Thank you for replying! It's not the belt. When it work, the arm could move fine. I've several of this model of turntable (1600/1700). I mostly fixed the mechanical issue such as belt , or cleaning old grease. For electrical, specifically the cmos replacements, I only know how to follow the trouble shooting chart from service manual. As such, I've replaced the IC460 and it works as described in my first post on this thread
 
The problem is the parts on these decks are old and a lot are past their lifetime. Not an expert, can only relate my experience which was a barn find 1610 Mk ll that was so dirty I just started taking it apart for a clean/re-lube and re-cap. Didn’t have a problem with my return, but believe that’s a lamp and a sensor with a plate with a slit that aligns to send light to a sensor and creates a voltage change. I’d check the status of the parts in the return system.

After that start looking at caps, clean the control switches if you haven’t, and make sure the contacts to all the plugs were clean and had good joints. Chips fail, but in my experience anyway, they’re lower on the list,
 
Make sense, what you've done, if you've done it without first experience any issue, is a reasonable approach. I do suspect the capacitors may be the cause. I am hoping to have some idea before I do it. I've read many on here and Vinyl Engine that people done a bunch of things and still issues remain
 
I had a similar issue on my 1700mk2 a few years ago with the auto return and cueing working intermittently mostly not. After a while I finally noticed my vta adjustment wheel was turned all the way up. I don't remember doing that but anyway when I put it in a normal range the problem went away.
 
Chrisxo55441 said:
I had a similar issue on my 1700mk2 a few years ago with the auto return and cueing working intermittently mostly not. After a while I finally noticed my vta adjustment wheel was turned all the way up. I don't remember doing that but anyway when I put it in a normal range the problem went away.
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Interesting, have you discovered what was the connection between VTA and the auto return function ? My issue seemed purely electrical
 
Intermittent problems are often dry cracked solder joints. Go over the control board with a soldering iron and fresh solder.
 
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