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

Ronald wrote:
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

The way I would suggest is to remove the 15 volt regulator (positive 15, I
assume) and connect the positive lead from the power supply right there or
at the capacitor which would usually follow. The ground of the power supply
would connect to chassis ground. If the supply is adjustable, you can start
at a lower voltage.

The shorted or leaky part is probably on the DSP board or an input switching
IC near the inputs, or maybe one or more bad op-amps.

One thing. If it's really a dead, dead short, i.e. zero point zero ohms,
then just feeding your power supply into it might not reveal anything, since
some resistance is necessary in order for the bad part to generate heat.
This is pretty rare but I have seen it happen. However, your regulator IC
would probably just shut down if this were the case.

Mark Z.

With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm and
one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron


On Feb 24, 4:39 pm, "Mark D. Zacharias"
wrote:
Ronald wrote:
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

The way I would suggest is to remove the 15 volt regulator (positive 15, I
assume) and connect the positive lead from the power supply right there or
at the capacitor which would usually follow. The ground of the power supply
would connect to chassis ground. If the supply is adjustable, you can start
at a lower voltage.

The shorted or leaky part is probably on the DSP board or an input switching
IC near the inputs, or maybe one or more bad op-amps.

One thing. If it's really a dead, dead short, i.e. zero point zero ohms,
then just feeding your power supply into it might not reveal anything, since
some resistance is necessary in order for the bad part to generate heat.
This is pretty rare but I have seen it happen. However, your regulator IC
would probably just shut down if this were the case.

Mark Z.- Hide quoted text -

- Show quoted text -

Ronald wrote:
With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm and
one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron


snip.

Get the IC numbers off the board and you can get order them from Andrews
Electronics. Their number is 800-289-0300.

Also, I have seen the TC9273N-004 from Onkyo cheaper. Not sure about the
other. Their number is 800-229-1687. They can look up the generic Toshiba
numbers you gave - at least they've been able to when I called on one
before...


Mark Z.

On Mar 2, 6:08 am, "Mark D. Zacharias" wrote:
Ronald wrote:
With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm and
one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron

snip.

Get the IC numbers off the board and you can get order them from Andrews
Electronics. Their number is 800-289-0300.

Also, I have seen the TC9273N-004 from Onkyo cheaper. Not sure about the
other. Their number is 800-229-1687. They can look up the generic Toshiba
numbers you gave - at least they've been able to when I called on one
before...

Mark Z.
Got my replacement parts in no dice. One gets real warm. I'm
thinking this amp is screwed. I've only put about 30 bucks in parts
into it. I have no clue what else to look for.

-Ron

Ronald wrote:
On Mar 2, 6:08 am, "Mark D. Zacharias" wrote:
Ronald wrote:
With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm
and one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron

snip.

Get the IC numbers off the board and you can get order them from
Andrews Electronics. Their number is 800-289-0300.

Also, I have seen the TC9273N-004 from Onkyo cheaper. Not sure about
the other. Their number is 800-229-1687. They can look up the
generic Toshiba numbers you gave - at least they've been able to
when I called on one before...

Mark Z.
Got my replacement parts in no dice. One gets real warm. I'm
thinking this amp is screwed. I've only put about 30 bucks in parts
into it. I have no clue what else to look for.

-Ron

I don't think those chips get warm normally. Could be one of the plus or
minus 15 volt lines is high. You could still have a blown channel, or a bad
voltage amp IC...

Mark Z.

On Mar 9, 8:05 am, "Mark D. Zacharias" wrote:
Ronald wrote:
On Mar 2, 6:08 am, "Mark D. Zacharias" wrote:
Ronald wrote:
With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm
and one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron

snip.

Get the IC numbers off the board and you can get order them from
Andrews Electronics. Their number is 800-289-0300.

Also, I have seen the TC9273N-004 from Onkyo cheaper. Not sure about
the other. Their number is 800-229-1687. They can look up the
generic Toshiba numbers you gave - at least they've been able to
when I called on one before...

Mark Z.
Got my replacement parts in no dice. One gets real warm. I'm
thinking this amp is screwed. I've only put about 30 bucks in parts
into it. I have no clue what else to look for.

-Ron

I don't think those chips get warm normally. Could be one of the plus or
minus 15 volt lines is high. You could still have a blown channel, or a bad
voltage amp IC...

Mark Z.- Hide quoted text -

- Show quoted text -

Now when I put the new chips in, I unsoldered the amp transistors all
of them. I can unsolder the zig zag'd ic's I had to replace one of
these in my other receiver that had a protection issue. the -15 volt
line seems stable its not warm. the +15 line is hot to the touch.
But not scolding hot like it was before. its about the same temp as
the -15. i can go though and unsolder the ic amps and the transistors
amps, and unplug the bias's. One thing odd that I noticed. when I
plug in the tuner module the amp goes into protection mode right
away. I happen to have an extra module. plugged that in and got the
same results. Now with these replacement chips I got the Toshiba
TC9273N-004 and TC9273N-013 I found a toshiba tc9273n-007 this is
what I replaced them with assuming the pinouts are the same. my guess
is they aren't . I don't know where to get some information on
these. I can order the 'correct' chips from andrews like you
recommend. But thats what I have done so far. Mark I appricate all
your help! Most people would stop and not bother to help. You
stick around. Thanks for that bud!

-Ron

Ronald wrote:
On Mar 9, 8:05 am, "Mark D. Zacharias" wrote:
Ronald wrote:
On Mar 2, 6:08 am, "Mark D. Zacharias"
wrote:
Ronald wrote:
With your help we found the short. it in two switching chips... I
need some help locating them.

Toshiba TC9273N-004 and TC9273N-013 these both got real warm
and one let out a puff of smoke so we nailed it.

Thanks for all your help if you have any insites... let me know

-Ron

snip.

Get the IC numbers off the board and you can get order them from
Andrews Electronics. Their number is 800-289-0300.

Also, I have seen the TC9273N-004 from Onkyo cheaper. Not sure
about the other. Their number is 800-229-1687. They can look up the
generic Toshiba numbers you gave - at least they've been able to
when I called on one before...

Mark Z.
Got my replacement parts in no dice. One gets real warm. I'm
thinking this amp is screwed. I've only put about 30 bucks in parts
into it. I have no clue what else to look for.

-Ron

I don't think those chips get warm normally. Could be one of the
plus or minus 15 volt lines is high. You could still have a blown
channel, or a bad voltage amp IC...

Mark Z.- Hide quoted text -

- Show quoted text -

Now when I put the new chips in, I unsoldered the amp transistors all
of them. I can unsolder the zig zag'd ic's I had to replace one of
these in my other receiver that had a protection issue. the -15 volt
line seems stable its not warm. the +15 line is hot to the touch.
But not scolding hot like it was before. its about the same temp as
the -15. i can go though and unsolder the ic amps and the transistors
amps, and unplug the bias's. One thing odd that I noticed. when I
plug in the tuner module the amp goes into protection mode right
away. I happen to have an extra module. plugged that in and got the
same results. Now with these replacement chips I got the Toshiba
TC9273N-004 and TC9273N-013 I found a toshiba tc9273n-007 this is
what I replaced them with assuming the pinouts are the same. my guess
is they aren't . I don't know where to get some information on
these. I can order the 'correct' chips from andrews like you
recommend. But thats what I have done so far. Mark I appricate all
your help! Most people would stop and not bother to help. You
stick around. Thanks for that bud!

-Ron

The tc9273n-007 would not be interchangeable. These chips are pretty
special.

mz