sony str de-345
 

Does any one know why sound cuting out repaired cold soder joints now
it says protect only ? Does anyone have a schematic for this sony str
de-345 unit thanks. Could it be a bad transister .

sony str de-345
 

wrote in message
ups.com...
Does any one know why sound cuting out repaired cold soder joints now
it says protect only ? Does anyone have a schematic for this sony str
de-345 unit thanks. Could it be a bad transister .


Check your inbox. I have sent you a PDF of the relevant schematics. As far
as your problem goes, first the obvious, make absolutely sure that you have
not introduced any whiskers with your reworking of the bad joints, and
second, are you retesting with the pcb and any rear panel connectors,
screwed firmly back down to the chassis ? These STR series amps are
notorious for giving a protect condition if not, due to the fact that
several grounds on the pcb are only made to one another via grounding points
screwed down to the metalwork.

Arfa

sony str de-345
 

Arfa Daily wrote:
wrote in message
ups.com...
Does any one know why sound cuting out repaired cold soder joints now
it says protect only ? Does anyone have a schematic for this sony str
de-345 unit thanks. Could it be a bad transister .


Check your inbox. I have sent you a PDF of the relevant schematics.
As far as your problem goes, first the obvious, make absolutely sure
that you have not introduced any whiskers with your reworking of the
bad joints, and second, are you retesting with the pcb and any rear
panel connectors, screwed firmly back down to the chassis ? These STR
series amps are notorious for giving a protect condition if not, due
to the fact that several grounds on the pcb are only made to one
another via grounding points screwed down to the metalwork.

Arfa

The ground screws were a problem years ago - now if it's a similar problem,
it would more likely relate to a soldered ground connection associated with
the rear panel. I agree the OP may have introduced a failure, though. Close
inspection of his work is indicated, and the usual DC voltage checks to
narrow down the protection problem. May very well wind up being over the
OP's head to fix this one.

Mark Z.

sony str de-345
 

"Mark D. Zacharias" wrote in message
et...
Arfa Daily wrote:
wrote in message
ups.com...
Does any one know why sound cuting out repaired cold soder joints now
it says protect only ? Does anyone have a schematic for this sony str
de-345 unit thanks. Could it be a bad transister .


Check your inbox. I have sent you a PDF of the relevant schematics.
As far as your problem goes, first the obvious, make absolutely sure
that you have not introduced any whiskers with your reworking of the
bad joints, and second, are you retesting with the pcb and any rear
panel connectors, screwed firmly back down to the chassis ? These STR
series amps are notorious for giving a protect condition if not, due
to the fact that several grounds on the pcb are only made to one
another via grounding points screwed down to the metalwork.

Arfa

The ground screws were a problem years ago - now if it's a similar
problem, it would more likely relate to a soldered ground connection
associated with the rear panel. I agree the OP may have introduced a
failure, though. Close inspection of his work is indicated, and the usual
DC voltage checks to narrow down the protection problem. May very well
wind up being over the OP's head to fix this one.

Mark Z.


Hi Mark

Well, I have sent the schematics directly to him as he requested, so it's in
his hands now. I've heard nothing back so far ... I still fool myself on
various amps with grounding issues - and how many years have I been at it ??
Just yesterday, I did a Pioneer amp that was intermittent as hell. To get at
the board bottom involved taking it right out, and also removing the rear
panel to get enough clearance to hinge it up. It was littered in obvious dry
joints ( it looked like he dreaded lead-free solder ), so I reworked them
all, and confidently stuck the board back in, screwed it back down, and put
a couple of screws into the back panel just to hold it in place. I switched
on, and it all worked ok - until I moved it on the bench that is ... It
promptly cut out into protect. Several minutes of cursing later, I realised
that a couple of the RCA jack assemblies had metal fingers up the fronts of
them. Once the screws had been put in these to bond them firmly back to the
rear panel, all was well, so this is something that the OP should definitely
check, as you say.

Arfa