[TechAssist] Re: Sanyo DS31590 partial schematic needed
- From: "Dave Routson" <davestv@xxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 19 Sep 2002 12:46:40 -0500
Hi John,
The 9V source is there but I am having trouble tracing
where the 7V source originates. B+ is 112V but set
will not power up since voltages to sweep Ic apparently
not right yet. I didn't have to replace Q601 or Q604
but did have to replace the drivers and opto. Before
replacing the drivers and opto-isolator with a light bulb
load across HOT and HOT loose, B+ was 289V.
There is a test point TJ7 that shows on the pcb 7.6V and is located close to
the tuner and in the vicinity of the sweep IC but it has
zero voltage and does not read short to ground. Tracing
back it ends up on Q627 Collector. It may be that this
voltage is not developed until set is turned on so I will
check into your instructions with D680. Also my 5V is
a bit low, only 4.23V so must still have loads.
Thanks for help.
Dave Routson
Dave's TV
208 Stroud
Cleburne, TX 76033-8738
Ph. 817-641-8465 fax same
email. davestv@xxxxxxxxxxx
----- Original Message -----
From: "John Mielke" <maintv2002@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, September 19, 2002 11:54 AM
Subject: [TechAssist] Re: Sanyo DS31590 partial schematic needed
That exact set is in Sams 4355 or very similar sets are in Sams 4363 and
4339 and others. Do you mean the 7 and 9v sources are there but low?
What is the +130v source? This power supply runs all the time but at
about 60% (the 130v source is about 75v) when in standby. To force the
power supply on, short the anode of D680 to ground. To force the entire
set on short the cathode to ground. With a lightning damaged set we
have seen the audio output short to load down the power supply. BTW, if
you need to replace Q601 and Q604 you need to use the exact transistors
(generic OK) but not NTE or they run very hot and will short again.
They are 2SC4423 and 2SC3807. John.
John Mielke
Main TV
636 Main St.
Longmont, Co.
maintv2002@xxxxxxxxxxxxx
Dave Routson wrote:
> This Sanyo had power surge and every section lost
> power. I have replaced all regulators, HOT, opto-isolator and still have 9
> and 7V sources not all there.
> Thought maybe someone has a scan or partial of
> SMPS where I can trace out losses. I am just about
> to zero this one but thought I would ask first.
> Thanks for any help.
> Dave Routson
> Dave's TV
> 208 Stroud
> Cleburne, TX 76033-8738
> Ph. 817-641-8465 fax same
> email. davestv@xxxxxxxxxxx
>
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--
John Mielke
Main TV
Longmont,Co
303 776 6955
maintv2002@xxxxxxxxxxxxx
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