Monitor fault

[Mike Brett]

I have been given a Amstrad PC ECD monitor that had no screen image. Having removed the back I managed to get a light blue screen image by adjusting the two controls on the tube transformer, not sure if its called that but it has one thick wire that goes to the side of the CRT. However after turning of the set to replace the back on switch on I could not get any image again. Do you think by adjusting the transformer I have blown something.
Cheers Mike

[Silicon]

Look for 'dry joints' on the pcb. Use a bright light and magnifying glass.

Transformers, large resistors and anything that gets hot or vibrates are a good starting point for intermittent faults.

[McMurdo]

The knobs you have turned on the back of the transformer are for focus and A1 voltages. By turning up the A1 voltage you have forced the tube to show some light, but it should be returned to where it was. Having the voltage too high can cause the monitor to trip out amongst other things.
Please consult someone who knows what they're doing!

[mike_newcomb]

Hi Mike,

in case you are unaware, please be careful what you are doing, as there are voltages inside monitors and tv's that can kill.

Also capacitors remain charged after switching off and/or disconnecting from the power supply and can give you quite a shock.

If this is only a monitor, why bother with it?

Amstrad equipment is not the best in the world. A local pc shop almost certainly has a working 14" monitor they can give you, as no one wants them nowadays.

Good Luck - Mike

[cmjones01]

It may only be a monitor, but it's not a run-of-the-mill VGA/SVGA one. It's an Amstrad 'ECD' (Enhanced Colour Display). If I remember rightly, that means it supports EGA resolution (640x350) with a horizontal scanning frequency of 15.7 or 21.8kHz. There aren't many monitors left which support this resolution, and therefore it's a hard thing to replace if you want to keep such a computer original.

Mike, what are you thinking of using the monitor for? It should work with 1980s home computers like the BBC Micro which give a TTL RGB output, as well as with EGA-era PCs. It won't work with anything more modern, or anything which needs an analogue RGB connection like an Archimedes, ST or Amiga.

Chris

[AC/HL]

The two controls on the LOPT will be focus and the high voltage for the tube's first anode.
Raising it will upset the black level and probably the blanking, but should not cause any damage.

[paul.brett]

The issue has been resolved.

The monitor has been deemed beyond repair, and we instead decided that a stand-alone power supply was the way to go.

The voltages (that supply the computer) have been identified, and an old PC power supply has been 'bodged' into something that works.

The onboard graphics were disabled (something which some websites say is impossible) and a suitable VGA card fitted.

I have asked my dad to keep the monitor plastics, and I may yet find a way to get a modern LCD screen attached (at least to the base, which fits snuggly in the main PC unit.)

TTFN.

Paul.

[Nickthedentist]

Well done.

Your pic brings back memories of my PC1640 from J.Bull Electrical, with some weird and wonderful uncased SMPS powering it via a huge DIN plug (fun to wire ), and an ancient IBM green CRT VDU as the display. It worked wonderfully and I used it until I could finally afford a s/h Win95 PC.

Nick.

[jay_oldstuff]

Snap Nick I too bought one from J Bull Electrical and bodged my own PSU mine I think was from a dead IBM TX and i used an old Wise terminal monitor i dug out of a skip, did most of my GCSE course work on that computer.

Jay

[paul.brett]

Originally Posted by Nickthedentist

Well done.

Your pic brings back memories of my PC1640 from J.Bull Electrical, with some weird and wonderful uncased SMPS powering it via a huge DIN plug (fun to wire ), and an ancient IBM green CRT VDU as the display. It worked wonderfully and I used it until I could finally afford a s/h Win95 PC.

Nick.

I seem to recall, it was you who gave me an Amstrad about five years ago.

Paul.