Info needed on 2 tough repairs...

[Vector Viper]

1) Mistubishi CK3551R tv (1987; old!)
No power up, no response from remote or any buttons.
standby supply runs fine, caps replaced on both standby and main
supplies.
forcing set on with relay jumper gives a totally black screen (has
horiz+vert sweep+filament)
microprocessor getting +5 volts, and keyboard/remote signals ARE getting
to its
input pin. Relay output pin can work relay. Microprocessor seem stuck in
reset or brain dead?
cust says it worked int. before cut out. Any advice? I'm thinking service
manual now...
Does anyone have a pin-out/specs for a M50441-564sp micro?
Or on vs. off voltages on the connector "SA" on the video board?!

2) Sony 32" KV32XBR37 Chassis SCCF84VA
Came in dead, had the classic blown power regs (C4834)+blown output
(C4927)
Replaced all+the black vdr, found bad connection on 'E' of hor-out,
thought it fixed
after soldering everything....
Horout will now run MAYBE 1 min before blowing; gets hot pretty
fast....can't see pix
before this happens. Did sub a D1880 for hor out to get this
time;original
C4927 blows in SECONDS. For each horiz pulse at HOT, the trailing edge
is lifted off the
baseline (not sharp) tried swapping flybacks with a known good one with
no change.
disabling pincushion by pulling link coil WILL allow set to run with
bowed picture,
but HOT still gets too warm....What could the problem possily be?! bad
yoke???
The yoke is a 8-451-315-41. The hor winding measures 713uh on mine, if
someone has a listing
on specs for this part, let me know? I'm really stumped on this one...

Thanks for any help,

Aaron H.

 

[John Del]

Subject: Info needed on 2 tough repairs...

From: "Vector Viper" [email protected]
Date: 1/25/04 2:06 AM Pacific Standard Time

C4927 blows in SECONDS. For each horiz pulse at HOT, the trailing edge
is lifted off the
baseline (not sharp) tried swapping flybacks with a known good one with
no change.

You didn't state your source for the semis. Unless these are KNOWN originals,
you might be chasing your tail. There are Chinese sourced counterfeits that
are indistinguishible from the OEMs.

John Del
Wolcott, CT

"I'm just trying to get into heaven, I'm not running for Jesus!"
Homer Simpson

(remove S for email reply)

 

[Jerry Greenberg]

You must absolutely use origional Sony semiconductors. These are
"Select On Test" for Sony. Using other generic parts will result in
what you are describing. Also when changing the horiz output on this
model, it is recomended to change the flyback assy. From memory this
will include the HV multiplifer.

I have found the driver transformer that is driven from a transistor
amp stage, that feeds the HOT will sometimes fail, or be intermittant.

Make sure that you also re-change the power supply driver transistors
in the power supply, and HOT (horiz output transitor) in the horiz
output stage.

Do an ESR test on all the caps in the power supply, and horiz output
section. Also do an ESR test on all the caps in the vertical section.
These are also troublesome at times.

Test all the high speed diodes, on the secondary side of the flyback
transformer. Also test all the caps in this area as well. Do an ESR
test to verify their performance.

Make sure that the scan gen IC is working correctly, and that there is
proper scans up to the HOT. If there is a scan drive failure to the
HOT, this will also cause it to fail, and take down everything with
it.

If you want high reliablity, only use Sony origional semiconductors
when servicing this set! Make sure that there are no shorts, and that
you found the cause of the failure in the first place before applying
back the power to set. New parts can fail as soon as the power is
applied back, if it is not serviced properly.



Jerry Greenberg
http://www.zoom-one.com