Date   : Tue, 17 Mar 2009 04:22:36 +0000
From   : mike@... (Mike Tomlinson)
Subject: Microvitec Tripler

In article <d8834d20903150649s35c1f148k73eb93fce6a645cf@...>,
Alex Taylor <zeem.uk@...> writes

>I've got a late model (early 90s) 1431 that won't quite focus. The
>control operates smoothly, and I think the unit's not had much use,
>but the 'best' position of the adjustment isn't quite good enough.
>What could cause that?

If it's Series 3 chassis (the one with the tripler on the rhs) most
likely the tripler (best tested by substitution), but first check the
voltage at the right hand side of R138 at the board edge, rear of
cabinet, behind the line output transistor.  It should be 124V.  If it's
lower, that suggests a fault elsewhere pulling the PSU down.  Does the
line whistle sound normal?

If tripler and HT voltage supply are OK, sounds like the tube.  MV used
cheap and nasty tubes towards the end of Cub production (made by some
Chinese company beginning with C - maybe Chungwa).

Though as you say it's a late model, does it have the series 4 chassis?
- the model number will be 1431-MS4F.  This uses a flyback transformer.
Again, most likely to be that.

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