28 Jan
2011
28 Jan
'11
1:20 p.m.
Colour PAL board - modulator goes to TV out and
composite plugs into this
too instead of VDU #1
Is this a normal sized board in one of the card guides? As Jules said,
the RGB output board isn't, it's a little board an an L-brackt fixed ot
the rear panel.
I assume you also havea modulator on the text video board (VDU #1). The
TV output socket cable is connected to that if you don't have the PAL board.
Incidnetlaly, I've just rememberd I ahve a somwaht odd RML380Z board
soemwhere. It's got a bit off address deocding logic on it,
interconnected by PCB tracks. And 3 (I think) Z80-PIOs and a Z80-CTC in
wire-wrap sockets. The Z80 bus linesare are connected to the 380Z bus
connector, etc. the port lines and the counter/timer signals go nowhere.
There's also a little prototyping area on the board and space to fit some
header plugs. The idea is that you make your own custom interfce by
adding the logic you need and wire-wrapping it to the PIO and CTC pins.
Ans wire-wrap it to a header plug to connect a cable to the peripheral.
I would love to find some of the other board too. There was rumoured to
be an GPIB board. And an Econet interface. Oh, and a scheamtic of the
cassette control box would be intreresting.
Done all that, the boards are in great condition as is the PSU internals.
Problem is the glass fuse has blown and I don't have a spare at home, bah.
It needs 250V/1A and all I have easy access to are PETs which are 250V/.75A.
Fuses generally blow for a reason. I asusme this is a mains fuse (in
series with the live side of the mains), in which case the problem could
be a short on the primary side (e.g. a filter capacitor, if they're after
the fuse), or a short on the seondary side (redtifer diode, smoothing
capacitor, etc0.
I really would try the series light bulb trick in this case. Start with
all the secoadary wires disconnected from teh trransfoerm, and power up
wit ha ligth bulb in series with the mains live wire. It should be dark.
If it glos, there's a short somwhwere. Power-down, reconnect the secondary
wiring, but have the PSU unplugged from the rest of the machine. Power up
a gain with the bulb in series. It will probabyl flash at power-on as the
smoothing capacitors charge, and it may stay glowing, but dimly. If it's
bright, I think you have a shorted rectifier or smoothing capacitor or
similar.
Of course findign a 100W bulb these days is a problem :-(
-tony