Date   : Sun, 15 Mar 2009 08:58:23 +0000
From   : mike@... (Mike Tomlinson)
Subject: Microvitec Tripler

In article <d8834d20903131306u5e584ca4m3f98256ac76b2231@...>,
Alex Taylor <zeem.uk@...> writes

>There are a couple of different types (see my comments below about
>blue and green ones)

The green ones are far more common, I only ever saw a couple of the blue
ones.  The focus pot goes on the green ones; it seems to develop a pit
on the carbon track where the wiper contacts it and knob becomes
"crunchy" in feel as you rotate it.

The same thing happens with the A1 control in the top left corner of the
tube base board (VR902 maybe IIRC), it's 1.2M. If you look at the white
centre of the trimpot (where you use the trimmer tool), on most Cubs of
a certain age, you'll see it's browned with heat and falls apart if you
try to adjust it.

>. I pulled apart the focus control on a blue one
>and it's just a carbon track on plastic with a knob assembly that
>clips to the front. It seemed to come apart and go back together
>without any problems.

The focus pot on the blue triplers seems to be reliable.  Hope you kept
the ones of the triplers you had fail; they may be handy for fixing
green triplers.  Yyou'd need to epoxy it in place or something, it won't
be a straight swap.

>I've had two blue ones fail with exactly the same fault, which was
>that they drifted massively out of focus as they warmed up. I replaced
>them with green ones salvaged from two other Cubs with much more
>complicated faults.

Good idea.

That said, Cubs almost always fail with a few stock faults (I fixed
hundreds of them during my time at an Acorn dealer.)  If you're stuck
with one do post here and I'll be pleased to help.

-- 
(\__/)   
(='.'=)  Bunny says Windows 7 is Vi$ta reloaded.
(")_(")  http://imgs.xkcd.com/comics/windows_7.png