[sdiy] MKS70 power supply issue

[w.james.meagher at gmail.com]

Thanks Christian, 

This makes good sense, and everything else is functioning and metering properly.

Cheers,
James

Sent from my iPhone

On 2012-11-15, at 12:39 PM, ChristianH <chris at chrismusic.de> wrote:

> On Thu, 15 Nov 2012 10:52:13 -0600 w.james.meagher at gmail.com wrote:
> 
>> Thanks for the suggestions everyone, I'll investigate further when I'm back in town on Monday. 
>> 
>> What I do know off the top of my head is that the mains in these parts run at 120V, not 117V - I'll test for further particulars when I'm back.
>> 
>> I agree that it would be nice to know where the +7Vunreg is supposed to be going, but I really can't make it out on my poor copy of the assigner and other schematics. I'll see when I'm back if there's a JX10 service manual out there (that might be clearer than my MKS70 manual), to shed some light on the +7unreg's destination.
>> 
>> I also recall that there's a diode in that PSU I was eyeing suspiciously (as someone else here...or on AH...has suggested), so I'll also test that one when I'm back to make sure it hasn't failed.
> 
> 
> As far as I can see in the JX10 circuit (assuming no big difference to
> the MKS), the +7V only goes to the 5V regulator and to the PG800
> connector (which most probably has its own 5V regulator).
> 
> My guess is that "+7V" isn't to be taken literally, it appears to mean
> "something sufficient to drive a 5V regulator". 
> If it was something like 15V or more I would start to worry, but as
> others have pointed out, if mains voltage is somewhat above nominal
> value (e.g. 240 vs. 220V), 10V doesn't look overly suspicious to me.
> That's what voltage regulators are for :-)
> 
> Christian
> 
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