68kMLA Classic Interface

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Analog board with Voltage too low then too high

Posted by: bibilit on 2015-12-07 08:53:26 I have been busy this week with a Classic II A/B. Voltages were too low on the first place, so manage to replace the usual caps, but they remain low after the replacement. On a second try those were far too high (5 volt was 6.25 v and 12 v around 12.2) Any idea ?

Posted by: Ferrix97 on 2015-12-07 09:18:36 Try replacing the optocoupler or the two diodes nearby

Posted by: 360alaska on 2015-12-07 09:20:57 Did you adjust it? There should be a potentiometer: Let's start there... If you can't get a good result you can try to resolder PP1 and then replace the Optocoupler

Posted by: bibilit on 2015-12-07 11:01:32 Did you adjust it? No didn't touched it, can you advise where the Optocoupler is located ?

Posted by: 360alaska on 2015-12-07 11:54:43 Here: Part number : CNY75GB

Posted by: bibilit on 2015-12-08 08:36:08 Ok, thanks.

Posted by: bibilit on 2016-06-16 01:04:13 Update, Replaced the Optocoupler yesterday, and apart from a first boot when a cap bursted open (i realised i fitted it the wrong side) the AB board is working again. Some weldings were a bit weak, and after touching those up, voltages are fine ans steady.

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