Thomson 29MT52 (ICC9)
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Author: Pete - NZ
29 inch Thomson, Model 29MT52 (ICC9 series chassis).
Less than three years old it would to do 2 attempts at starting & cut back to the front red LED lit condition only. Obviously a European style of appliance & unusual to us in NZ where we see more often the range of Japanese/ Korean type sets. This one was purchased in Singapore and the owners had moved to New Zealand with it. Thomson agents locally were unable to supply support but the owner took it to a Service Centre who diagnosed a shorted LOPT so they advised it was unecconomical to repair!
I was asked to have a look before a 2 yr old 29 inch was to be dumped...
Since there was zero support for the chassis in NZ as far as i could acertain, i used the Internet & News Group sci.electronics.repair making a search using groups.google.com.
The first bit of info was to dis the protection circuit by removing transistor TP69 (SMD). It was the first break-through as the receiver now worked but had with frame collapse (no vertical deflection) problem.
Eventually, after MANY hours of 'red herrings' i found there had been considerable rework around IF01 (STV9379) the Vert deflection booster ic. The soldering was really bad so opted to completly wick-desolder & clean the tracks. I found 2 tracks broken/missing especially the feed to the yoke!
Repairing this we now had a going picture/sound. Reinstalled the protection TP69 (SMD) transistor & the receiver would startup ok but....
Lower part of picture had at least 1" of distorted line scan. Using a 'scope showed the vert pulse chain input to IF01 was ringing just before at the start of transition. The SMD capacitor CF01 that is mounted amoungst the pins of IF01's across #1 & #7 (i found the data sheet for IF01/STV9379 at www.ST.com ) was damaged by all the rework. Once replaced all OK.
So much for a failed LOPT!.... and a nice TV set to boot too. The owner is REALLY happy.
More ICC9 faults can be found on the forum HERE
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