Cinematronics/Vectorbeam Monitor repair mini-doc!

Generally speaking, these monitors are far simpler than the color vector
monitors
and so there is FAR, FAR less to go wrong. Here is the gist:

There are 4 neck wires with white "things" on them. The wires inside the
things WILL break at some point. Cut the things off and splice around them.
Does anybody know what those things are? While you are working on these,
ensure that none of the wires has broken off the PCB as this is very common.
ALWAYS DO THIS STEP!

Resolder all the connector pins; cracks from wiggling are quite common.
ALWAYS DO THIS STEP!

Replace most tantalum capacitors (regardless of values) with 22uf @50V
electrolytics (paying CAREFUL attention to polarity). I replace 10
including:
C4/10/12/13/15/23/25/105 and 2 others with no designation just off the
upper-right corner of IC201.
ALWAYS DO THIS STEP!

Check C102/202 for broken legs (common).

Replace the 47 Ohm, 1/2W R118-119/218-219 with 5W versions.
To do this, place them on the underside of the PCB. This may be skipped.

Replace al 1n400? with 1n4004 or higher which includes D105-115/205-215.
This step may be skipped but only takes a few minutes and costs next to
nothing.

Now if you are still blowing breakers, remove the connectors for the "HORIZ"
and "VERT" heat-sunk transistors, and retest for no more than 15 seconds or
so.
If you do this too long, you will burn up R118-119/218-219. You have much
longer before this happens if you upgraded them to 5W as advised earlier
(but
the 5W will still burn up and torch the PCB, too so don't get carried away).
Leave power on until breakers blow or until you see R118-119/218-219
begin to smoke/glow. When this happens, CUT POWER IMMEDIATELY!
The breakers should NOT blow and you should get a tiny (1" square) picture
(but don't bother watching for a picture;WATCH THE RESISTORS!)

Plug in the "VERT" and "HORIZ" connectors one at a time to see which one
(or perhaps both) causes the breaker to blow. Hopefully only one will be
found to be the culprit. Therefore you can use the working channel as a
reference against the non-working channel! First check the heat-sunk
transistors.
If one is bad upgrade to 2N3716/2N3792 as found in the Atari model's
vector monitors. These are beefier parts for the same purpose. Don't ask
me which substitutes for which; figure it out (that's what I do EVERY time
:)!
If they test good, test for case shorted to chassis (they should be
insulated
by a mica insulator). If that tests OK, then we move back onto the PCB.

Begin with Q109/209 (2N5322) as I find these are the next most likely
failures.
If one channel is working (very likely as per previous paragraph's testing),
test
Q109 against Q209 using an analog meter in "ohms/resistance" setting. Test
all 6 combinations of the 3 legs and make sure both transistors "look" the
same
on the meter deflections. If not, remove it and retest out of circuit
(should
have some resistance in 2 combinations and infinite in the other 4). If it
tests
bad out of circuit, replace it (I suggest Mouser as they carry all 5 types
of
transistors used and the 1N4004 diodes at good price). If it tests OK out
of
circuit, check adjacent transistors in the same manner until you find the
all
the ones which are bad and make the non-working channel's transistors all
mimic the deflections of the working channel's transistors.

I find about 80% of the bad transistors are shorted and about 20% are open.

Your monitor should now work at least so far as popping the breakers goes.
If your picture looks bad, try swapping your DAC-80 chips (IC-101/201).
If the badness moves to the other axis, that DAC is bad. If not, you may
also have a bad LF13331 which I have heard a lot about but have not yet
found ever to be bad.

If you have no HV, I can't really help you other than to suggest if you have
the external "Keltron" HV module, check the vectorlist as several people
got NOS units a while back from some mail order house that had a sizable
stash. Unfortunately, at least 2 greedy souls snapped up the stock and have
been Ebaying them so there are no more "cheap" ones left. I have yet to
run across a monitor with a HV problem.

The pins appear to be fragile on the neck so beware. I had one tube with
no heater glow and the problem was A PIN WAS MISSING! I was able
to use conductive epoxy to replace it after slightly chipping out the area.

If your picture is dim (i.e. Star Castle; what is the brand?), get it shot
with
a picture tube rejuvenator at any TV shop.

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Received on Thu Jul 4 23:13:40 2002