[sdiy] juno 60 death

[R. D. Davis]

Quothe gregory zifcak, from writings of Fri, May 07, 2004 at 09:45:21AM -0700:
> 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.

Haven't seen one on-line anywhere... got my schematic from Roland 
back in 1997.  Once you verify that the transformer is ok, and producing
the correct output voltages, here are some things to check next:

Looking at the PCB, find capacitor C2, 0.1uF (between fuse F1 and two
of the filter caps, just above C3), or the junction of C2, C1, the +
terminal of the bridge and the input of the 7805.  At that point, you
should measure approximately 9 to 10 Vdc.

At the output of the 7805, where it forms a junction with C4 (0.1 uF)
and the + side of C3 (10uF), you should measure 5Vdc.

On pin 4 of IC2, a TA7179P, where it forms a junction with R4 (1 ohm,
1/2W), D5 and R5 (10K, also connected to a 10K trim pot, VR1), you
should measure +15Vdc, +/-10mVdc.  If this is off by more than 10mV,
then you'll need to adjust the 10K trim pot, VR1 (see above).

On pin 11 or IC2, at the junction with R3 (1 ohm, 1/2W), C13 (0.1 uF),
C14 (10uF) and D4, you should measure -15Vdc.

Let us know what you find.

-- 
Copyright (C) 2004 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.