26 Jan
2011
26 Jan
'11
11:54 a.m.
On 25 January 2011 20:18, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Most of them have TV outputs, whether the PAL encoder is fitted or not.
The standard configruation (at least for 40 column machines, the 80
column video card is different, and I've never seen one), is that there's
a composite video output and a UHF TV output both fed from the text
system. If you add the hi-res card, the UHF output remains text-only,
the composite output carries text and hi-res suitably combined. There is
a header plug on the high-res board that carries the output of the CLUT
(8 bit), that's where the RGB board and I assume the PAL enocder are
connected. What I can't rememebr is if/how the text video output ends up
on those boards.
>
> Folks,
>
> Picked up one of these wee beasts today at long last, Z80 CP/M and CP/N
> machine from ~1981, complete with not-oft-spotted hi-res colour PAL boar=
ds
The H-res board is not that rare. The PAL enocder is, if you have that.
Yup, the machine has a TV-out as well as the standard monitor. The PAL
board is marked as such and has a colour modulator on it. Is this the 5.25" floppy version or the
8"? I thought the former normally
5.25". I've only ever heard talk of the 8" had the drives in the processor box, in which
case the cabel is internal
(but you say you've not dismantled it). The floppy controller is based on
a 1771, and has a standard Shugart-ish interface for the drives.
Yup, hence me raiding my store of Cumanas :) I should be able to get a Megger at work. The reason I
mention the
caps is because the last 3 or 4 machines I've had in have all blown
the mains filters.
Right.. Those are not the capacitors that most people replace without
testing on old machines...
Yes, mains filters can and do blow. I've replaced a few -- well,
actually, most of the time I've replaced the capacitors only (seaprate
components on a PCB). If there's potted filter module, I guess you
replace the whole thing.
I don;t think there's any way of telling if they're going to fail. One
time I was using an HP machine and for no apparaent reason one of the
mains filter capacitors in the monitor exploded. I removed it and carried
on using the monitor untiL i got a replacement. No other problems.
A failed mains filter may blow the fuse, but I doubt it'll do any more
damage to anything. I wonder if it's worth put a light bulb in series
with the mains live wire (that's a real light bulb, of course, not one of
those CFL things) and powering up the filter/transfoemr with the
secondary windings of the latter disconnected? It should catch
catastrophic failures with no further damage.
-tony