[TechAssist] Sony KV32S42 fixed

I just fixed two of these. One was mine because of a turned down estimate.

Also have a procedure at the end for testing the power supply out of the
set.

This is KV-32S42 with a power supply board on the side.
HOT was shorted on main board and the rest are all on the power supply
board.
IC601, R607, D648 (measured open so I replaced it).

On the second set I didn't replace D648 because the new part measures open
too, so I figured the one in the TV may not be bad after all, and apparently
it wasn't because it works fine.

C609, 10, 11, 12 for insurance.
I didn't have these 4 caps the first time I tried and IC609 shorted
instantly when I applied power.

The original failure appeared to be caused by the familiar H-driver
transformer connections.
Looks like a cascade failure similar to other Sonys with the two
transistors etc. in power supply when the HOT shorts.

There was a tip that mentioned IC1701 on the CRT board as a cause, but the
Sony tech said they never have a problem with it. He said if it still
doesn't work with the afore mentioned parts in it to check: Q644, D601,
D641,2,3,4,5,6.

OUT OF SET TEST:

Unplug from main chassis.
Replace parts.
Jump pins 10 & 11 on CN641 (connector to main chassis).
Monitor B+ across C643.
Bring AC up slowly (Sencore Powerite is handy)
@35v AC, the DC output should be 135v (mine came up @22vac)
Go to 60vac, 90vac, 120vac. Should stay at 135vdc. (mine was 137vdc)
power down, unhook jumper and put back in TV.

I brought the AC up slowly while monitoring the current in case there was
still something wrong with the chassis. When it fired up the current was
near 175 watts on the Powerite but it quickly came down as I increased the
voltage. Runs at about 90 watts, varying by picture content.



Russ Hoyt
Hoyt's TV
Exeter, NH




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