My friend Arvel is working to repair a B&O TX-2 turntable with an exotic, and somewhat intermittent issue that I'm unable to help with. This machine has a dual solenoid with uPC control that triggers several gap-toothed gear wheels for arm lift, arm start/stop, etc. The observed issue is a chattering of the solenoid and its lever controlling the 1604 cam's gap-tooth segment, causing intermittent operation. He has experimented with various lubes and various spring tentions, even with gear teeth profiles from a donor unit, but without really reliable results.
I have the service manual (actually two, wretched excess is the American way) and can post scans, but I suspect this is so exotic that only someone who's actually seen and solved the issue might have insight. Goes without saying, all the obvious issues of the solenoid drive electronics (all electrolytics replaced prophylactically, yada, yada) can be ruled out (But! Never say Never).
A Hail Mary pass, in case anyone might have seen this, and thank you,
Chris
I have the service manual (actually two, wretched excess is the American way) and can post scans, but I suspect this is so exotic that only someone who's actually seen and solved the issue might have insight. Goes without saying, all the obvious issues of the solenoid drive electronics (all electrolytics replaced prophylactically, yada, yada) can be ruled out (But! Never say Never).
A Hail Mary pass, in case anyone might have seen this, and thank you,
Chris
Chattering of the solenoid...could be not enough current to keep it engaged. Or low voltage. Maybe old caps in power supply could be replaced?
Thank you for your comment, and this was also my first question to Arvel. He's had his own repair biz for decades, well respected, yada yada, but it's always important to check, because as they say in the military "Two is one, and one is none."
I've seen this in person, and can confirm that the anomaly/fault is intermittent (about 50%) and cannot be reliably conjured into being. Hence, this cry for Divine Intervention. The solenoid and its lever appear to be chattering, trying to engage (through a simple lever) a 4 tooth segment of the gap-tooothed 1604 cam - very straight-forward stuff. On the electrical side, everything across the soleloid seems fine on the scope.
I wouldn't post this if I didn't believe due diligence hadn't been done. Based on Arvel's (and what I believe to be reliable) observations, the issue is not electrical, although it still may (IMO likely) involve the (replacement parts of course NLA) solenoids. What I'm hoping for is a Hail Mary pass, that wins the game, from someone who might have seen this and solved it already. If so, thank you; if not thanks for your time and thoughts.
All good fortune,
Chris
I've seen this in person, and can confirm that the anomaly/fault is intermittent (about 50%) and cannot be reliably conjured into being. Hence, this cry for Divine Intervention. The solenoid and its lever appear to be chattering, trying to engage (through a simple lever) a 4 tooth segment of the gap-tooothed 1604 cam - very straight-forward stuff. On the electrical side, everything across the soleloid seems fine on the scope.
I wouldn't post this if I didn't believe due diligence hadn't been done. Based on Arvel's (and what I believe to be reliable) observations, the issue is not electrical, although it still may (IMO likely) involve the (replacement parts of course NLA) solenoids. What I'm hoping for is a Hail Mary pass, that wins the game, from someone who might have seen this and solved it already. If so, thank you; if not thanks for your time and thoughts.
All good fortune,
Chris
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Another such thought could be the driver transistor for the solenoid. Just a stab in the dark...
Tom
Tom
Thank you for your comment. Looking at Arvel's troubleshooting, over more than a week, it doesn't seem as if the source of the issue is electronic, although it may still be the solenoid. But the scope shows no electronic problems, so neither of us has kept any hope alive in that direction.
The machine is kinda whiz-bang, but the problem itself is, on its face, pretty straightforward:
A solenoid driving a rocker arm driving a missing tooth segment of a toothed-gear cam - dead simple.
What I'm hoping to find is someone who has seen this anomoly before. Very poor odds, but worth asking, and possibly useful in future.
The machine is kinda whiz-bang, but the problem itself is, on its face, pretty straightforward:
A solenoid driving a rocker arm driving a missing tooth segment of a toothed-gear cam - dead simple.
What I'm hoping to find is someone who has seen this anomoly before. Very poor odds, but worth asking, and possibly useful in future.