[TechAssist] Sony TV KV27V15, power supply problem
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 20 Oct 2003 16:36:22 -0400
I have this Sony KV27V15 which came in with the HOT and power supply
transistors shorted. I replaced the HOT, resoldered the driver Xformer,
changed the 0.47uF, changed the 2 2SC4834's in the PS, plus the 3 VDR's,
the 4 -0.22 caps, R607 (0.1 ohm) and changed R644 from 6.8 ohm to 4.7
Ohm as per instructions. Checked all other parts in PS primary and sec.
for shorts, nothing else found.
Fired set up at 30 AC and did measurements with ground lead of meter and
scope on the junction of the 2 main filter caps. C607 (-) and C608 (+)
DC measurements:
Q601:
E= -1.5V
B= -1.7V
C= +49.6V
Q602:
E= -49.7V
B= -49.7V
C= -1.5V
I get a square wave of 100V p-p on base of Q601 but no waveform is on
base of Q602. I am expecting I should have 100V p-p only of out phase
compared to the Q601 base waveform. I checked Q602 with ohmmeter and it
checks ok. I checked winding of T603 pins 1 to 2 and pins 5 to 6 both
measure 0.6 ohms in circuit. I made a few other resistance comparisons
between the Q601 circuit and Q602 circuit and didn't find anything out
of line.
Just want to verify that I am doing this testing correctly before I
continue later tonight on this set. I will do more indepth invaluation
of the components in the base circuit of Q602. I'm supposed to have this
set ready for the customer tomorrow.
--
Thanks for any help.
Gary McCartney
McCartney Electronics
Guelph Ontario Canada
Est. 1984
email: gary (at) number63.ca
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