[sdiy] juno 60 death

[gregory zifcak]

great,
thanks for the help everyone. i'm going to go over there again this evening 
and take a closer look. i must have been metering wrong because nothing 
looks damaged. i didn't see any fuses after the mains fuse at first; that 
will be my next task. then i'll disconnect the transformer and measure the 
ohms. anyone know if there's a schematic online? thanks again for all the 
help.

greg

>From: "R. D. Davis" <rdd at rddavis.org>
>To: gregory zifcak <zifcak at hotmail.com>
>Subject: Re: [sdiy] juno 60 death
>Date: Thu, 6 May 2004 20:05:32 -0400
>
>Quothe gregory zifcak, from writings of Thu, May 06, 2004 at 04:00:16PM 
>-0700:
> > a friend's juno 60 suddenly stopped showing any signs of life. the fuse
>
>Hi, that's not good news.  After just obtaining a Kenton Pro-DCB for my
>Juno-60, I don't want to think about Juno-60 failures. :-)
>
> > appears to be intact. i measured some points with my meter, and it looks
>
>Did you check all three fuses at the power transformer secondary
>windings?
>
> > like the transformer is putting OUT 120v. this is not normal right? it
>
>That doesn't sound quite right.  Just a second... time to dig up the
>Juno-60 schematics... they're burried around here somewhere.
>
> > looks to me like the transformer has two outputs: 26vac and 18vdc. is 
>this
> > correct? what appears to be the two outputs both read 120vac. can anyone
>
>No, a transformer wouldn't have an 18VDC, or any DC output, for that
>matter.
>
>Ok, found the schematics.  The transformer's secondary has two
>windings; one of which is center tapped.  The first is 8.5 Vac where
>it connects to fuse F1 and bridge rectifier D1; these should be orange
>wires coming from the transformer.  The other winding: the center tap
>goes to chassis ground (black wire).  You should measure 18Vac between
>each of the red wires (going to fuses F2 and F3) and ground, or 36Vac
>between the two red wires.  Are you certain that you're measuring the
>output?  Does anthing look or smell burnt?
>
> > corroborate my hunches? i suppose i'll need to find a replacement. any
> > leads?
>
>First, let's verify that this is indeed the problem before thinking about
>specific replacement parts.  If that did indeed happen, and the fuses
>didn't blow, you will probably need to replace more than a transformer
>or even a few PSU parts, one would think, but let's not think that just
>yet.
>
> > also, wouldn't 120vac damage the voltage regulators and caps? they
> > don't look burned at all.
>
>One would think that some fuses would have opened if this was the
>case.
>
>--
>Copyright (C) 2003 R. D. Davis The difference between humans & other 
>animals:
>All Rights Reserved | My VAX | an unnatural belief that we're above Nature 
>&
>www.rddavis.org | runs VMS & | her other creatures, using dogma to justify 
>such
>410-744-4900 | doesn't crash!| beliefs and to justify much human cruelty.

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