Following on from my post of a couple of days ago, looking for a schematic set for a JVC with a dead radio section, not having found one, I had a little search through my extensive stock of JVC manuals, and came up with one for a similar(ish) model of the same vintage, which used the same radio tuner sub-board.Using this, I was able to determine that all rails were established and correct, that the PLL chip was idling and unlocked, that the FM subsystem IC was idling, and that the VFD for the radio section had the correct supplies and drives, but was being 'muted' by the drive IC, which is also the system control processor. No I2C data was being sent to the PLL IC, hence the reason that it never ramped the tune voltage to the RF module. The I2C bus was however, correctly active for other control functions, such as handling the CD section. About the only conclusion that I could come to, was that either the microcontroller was in some subtle way faulty or, more likely I felt, its software was screwed.Last week, we had a couple of claps of thunder locally, so I began to think that this might be a 'storm damage' job. Either way, in view of its age, it was not going to be a practical repair, so I informed the store that it came to me from, and put it back together. It was at this point that I noticed the PAT test label wrapped around its power lead, and this indicated that the test had been carried out only a week or so before it became faulty. At this point, I began wondering if the fact that it had had the tests performed on it, probably by someone with an automatic tester and little understanding of what it is doing, and where it is appropriate to run which tests, had resulted in damage to the microcontroller. I have seen other equipment on a number of occasions over the years, with similar 'odd' failures, and sometimes power supply failures, shortly after being PAT tested.I've never been a great believer in the appropriateness of applying these tests to double...

"Arfa Daily"re: JVC midi size hi-fi system.** Why on earth would a unit like that have to be PAT tested ????No requirement exists here in Australia for low risk items used in non hazardous work environments to be regularly tested..... Phil

On Fri, 18 Jun 2010 07:39:54 -0400 Tim Schwartz wrotein Message id: :First hit on Google.

PAT testing. Anyone else think that sometimes, it causes damage ?

Jun 17, 2010 22 Replies

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JW 16 years ago

First hit on Google.

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Adrian C 16 years ago

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OK, accepted. Didn't know about that 'code of practice' document.

Adrian C

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Cydrome Leader 16 years ago

brussels already looks burned down. bring wrecking balls and bulldozers and just till that place back into the ground.

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