Sanyo SMD

Submitted By Dr Neil A Mallett

After years of occasional TX90, TX100 and the odd Philips repair, the hospital where I worked decided to buy some Sanyo sets. Within days of warranty passing, these sets started to fail with PSU problems. These were the first tv’s I’d seen with hybrid devices, both through hole and surface mount devices.

I had experience of SMD, so they were of no concern to me. My ‘incident’ happened when I didn’t read the circuit diagram correctly and removed an opto isolator instead of another SMD device to test the psu. Sadly, this opto isolator was part of a feedback loop to set ht: as there was no voltage seen on its return leg. The psu kept on ramping up voltage until all of a sudden, a hundred fleas leapt from the circuit board, or in real terms, every smd transistor had decided to deposit its innards all over my bench.

Soon after, we recruited a new trainee engineer, and it was my job to teach him about medical engineering. Thankfully, he was previously a TV engineer, so I never had to take the back off another set in my days there.

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