Philip Pemberton wrote:
I've got an Acorn AKF-17 on my workbench, serving
duty as a test monitor
and the display for my Acorn A3000. For those not in the know, it's
essentially a Philips CM8833 Mk.II chassis with most of the inputs
blanked off. It's actually quite a nice monitor, except the power switch
is on the back (I prefer front-mounted power switches) and it's not
quite as nice looking as the metal-case Microvitec Cub (which has a nice
industrial look going for it).
Here's the catch. It seems to have a bit of a problem in the video
synchronisation department.
Specifically, the picture rolls vertically (from bottom to top), and
seems to move to the right as it does so. In other words, a vertical
line turns into a forward-slash.
Has anyone worked on one of these "fine" monitors (CM8833, CM8833 Mk2,
AKF17 or one of the many re-brands e.g. Atari SC1435) before?
What should I be staring daggers at first?
Does anyone know where I might be able to get a service manual (or at
least a schematic set)? I've got the Mk1 schematics and service manual,
but not the Mk2. Apparently someone posted them to Rapidshare last year
but the link is now rather dead :(
Also, does anyone know where I might be able to get a new power switch?
Apparently it's an ITT ME5A, Philips 12NC number 4822 276 11504 though I
can't confirm this (I don't have an AKF17 or CM8833mk2 service manual).
I've ruled out the A3000 -- MonitorType is 0 (TV-rate monitor) and Sync
is 0 too (composite sync). If I switch to Separate Sync (MT0/SYNC1), my
LCD monitor (an NEC EA231WMi) will lock on and display video...
Cheers,
With anything over about ten years you start by replacing electrolytic
capacitors. If you want to test instead of shotgun then pick up an ESR
meter, but it usually shows more than a few are failing. If the monitor
is over twenty years old, then just replace all the electrolytics and
then troubleshoot - it there is still a problem that is.
Do take care to match the caps to the job they do - low ESR caps for the
horizontal, and caps that handle AC ripple for the linear power supplies.
John :-#)#