VR241 Service Manual?

tony duell ard at p850ug1.demon.co.uk
Sun Jun 5 09:11:57 CDT 2016

> Does anyone have a VR241 Service Manual?

> I have looked on Manx and BitSavers, but there doesn't seem to be one
> available in those places, and a more general search has failed to turn up
> anything either.

It's also not in (for example) the VT240 manuals. The VR201 is, but said 
manuals specifically refer you to a VR241 documentation set.

What do you need to know? I've reverse-engineered the schematic and
can send you that, but if you do delve inside (a) Good Luck and (b) be 
very careful. IIRC there is mains where you might not expect it.

It's a Hitachi chassis, and it shares some feautures with Hitachi televisions 
of the period. There is a thick-film hybrid module in the middle of the 
deflection board. It contains the sync/oscillator IC and the vertical output
stage. The IC, output transistors and a few other componets are soldered to
the module, the resistors are thick film traces. 

The power supply is evil. It's a switcher, and it runs off the _horizontal
deflection_ oscillator. So for the power supply to run, the horizontal
oscillator, horizontal output, flyback transformer, etc must all be good.
There is a little multivibrator on the PSU board to kick the thing into
life when you turn it on.


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