I just got this unit. It powers up and the protection kicks in. I've
repaired a 840 with this same problem. but it appears on this unit
the 15 volt regulator gets real hot. I've replaced it already with
the same results. If anyone has any tips or pointers to where to look
I'd appricate it.

-Ron

Ronald wrote:
I just got this unit. It powers up and the protection kicks in. I've
repaired a 840 with this same problem. but it appears on this unit
the 15 volt regulator gets real hot. I've replaced it already with
the same results. If anyone has any tips or pointers to where to look
I'd appricate it.

-Ron

If the 15 volt reg gets hot, it seems to me there's some IC or other loading
it down. I'd sub in an external 15 volt or so and see what gets hot.

Mark Z.

On Feb 17, 4:01 pm, "Mark D. Zacharias"
wrote:
Ronald wrote:
I just got this unit. It powers up and the protection kicks in. I've
repaired a 840 with this same problem. but it appears on this unit
the 15 volt regulator gets real hot. I've replaced it already with
the same results. If anyone has any tips or pointers to where to look
I'd appricate it.

-Ron

If the 15 volt reg gets hot, it seems to me there's some IC or other loading
it down. I'd sub in an external 15 volt or so and see what gets hot.

Mark Z.

I just got a schematic for it. Traced back to the diodes on the dc
power board. Gonna replace them tommarow. Odd readings on the
diodes, in diode test i tested it both ways one reading of 1.1 and .5
and a few just .5 in one direction. my guess from my repair work on
pinball machines .4 - .6 is ok diode but could possiable failed
diode. But I'm replacing them with new ones. to ensure a rebuilt
power supply.

-Ron

On Feb 19, 1:24 am, "Ronald" wrote:
On Feb 17, 4:01 pm, "Mark D. Zacharias"
wrote:

Ronald wrote:
I just got this unit. It powers up and the protection kicks in. I've
repaired a 840 with this same problem. but it appears on this unit
the 15 volt regulator gets real hot. I've replaced it already with
the same results. If anyone has any tips or pointers to where to look
I'd appricate it.

-Ron

If the 15 volt reg gets hot, it seems to me there's some IC or other loading
it down. I'd sub in an external 15 volt or so and see what gets hot.

Mark Z.

I just got a schematic for it. Traced back to the diodes on the dc
power board. Gonna replace them tommarow. Odd readings on the
diodes, in diode test i tested it both ways one reading of 1.1 and .5
and a few just .5 in one direction. my guess from my repair work on
pinball machines .4 - .6 is ok diode but could possiable failed
diode. But I'm replacing them with new ones. to ensure a rebuilt
power supply.

-Ron

Follow-up Bump..

I've replaced the diodes, still no change. I got a schematic off the
internet. finding a short in the 15 volt line is tough. my thoughts
if I unsolder the parts in the line it should resolve the short.
Replace them one by one until the short shows up. Sounds logical?

-Ron

I've replaced the diodes, still no change. I got a schematic off the
internet. finding a short in the 15 volt line is tough. my thoughts
if I unsolder the parts in the line it should resolve the short.
Replace them one by one until the short shows up. Sounds logical?

-Ron

If the 15 volt reg gets hot, it seems to me there's some IC or
other loading it down. I'd sub in an external 15 volt or so and see
what gets hot.

Mark Z.

I just got a schematic for it. Traced back to the diodes on the dc
power board. Gonna replace them tommarow. Odd readings on the
diodes, in diode test i tested it both ways one reading of 1.1 and .5
and a few just .5 in one direction. my guess from my repair work on
pinball machines .4 - .6 is ok diode but could possiable failed
diode. But I'm replacing them with new ones. to ensure a rebuilt
power supply.

-Ron



That's why I recommended subbing in an external 15 volts or so (with the
unit turned off and unplugged) and see what gets hot. Much quicker and
easier. Helped me fix many a unit. These pieces are so complicated that
tracing everywhere that 15 volt line goes would take way too much time and
effort.

Mark Z.

On Feb 23, 6:42 am, "Mark D. Zacharias"
wrote:
I've replaced the diodes, still no change. I got a schematic off the
internet. finding a short in the 15 volt line is tough. my thoughts
if I unsolder the parts in the line it should resolve the short.
Replace them one by one until the short shows up. Sounds logical?

-Ron
If the 15 volt reg gets hot, it seems to me there's some IC or
other loading it down. I'd sub in an external 15 volt or so and see
what gets hot.

Mark Z.

I just got a schematic for it. Traced back to the diodes on the dc
power board. Gonna replace them tommarow. Odd readings on the
diodes, in diode test i tested it both ways one reading of 1.1 and .5
and a few just .5 in one direction. my guess from my repair work on
pinball machines .4 - .6 is ok diode but could possiable failed
diode. But I'm replacing them with new ones. to ensure a rebuilt
power supply.

-Ron

That's why I recommended subbing in an external 15 volts or so (with the
unit turned off and unplugged) and see what gets hot. Much quicker and
easier. Helped me fix many a unit. These pieces are so complicated that
tracing everywhere that 15 volt line goes would take way too much time and
effort.

Mark Z.- Hide quoted text -

- Show quoted text -

should I tap anywhere in the 15 volt line? chassis ground or pcb
ground.

-Ron