[TechAssist] VS-5004R FIXED (Inter. Power On)
- From: Bil Green <tv.vcrrepair@xxxxxxxxxxx>
- To: ".TECHASSIST @ freelists . org" <techassist@xxxxxxxxxxxxx>
- Date: Sun, 31 Oct 2004 01:48:37 -0800
Mitsubishi VS-5004R PTV
Using STRS6301 SMPS IC
The original symptom was no power. Replaced the usual caps in the SMPS
(47mF, 100V - 10mF, 100V - etc.). All the electros near both power ICs
tested bad. Replaced the STRS6301 IC.
Then the set still would not turn on unless I applied the meter probe
to pin one of the STRS6301 (to check for 155VDC) while the on-off
relay was on. The set would then power up just fine, good picture,
etc. Removing the meter probe didn't cause the set to turn off.
After checking all the resistors I found that the 270k, 1/8W resistor
in the primary winding was open. It made sense since this resistor
was in the same part of the circuit as pin 1 of the IC (touching the
probe to pin 1 made the set turn on).
Now the set turns on fine. I posted this because too often large value
resistors have a small voltage across them and won't check properly
(as in this case) and it's easy to assume the resistor is OK and not
bother to check it out-of-circuit.
It's not always the low value resistors that blow out.
Bil Green
PC 1000
Mammoth Lakes, CA 93546
760-924-1000
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