Amstrad GT65-2 Green Screen Monitor repair.

[tibbs1972]

Hi all,

I purchased a GT65-2 Green Screen monitor on Ebay a few weeks ago for nostalgia, as that's what I had as a child.

On the website photos, it worked, but when i received it, it didn't.  Beware Ebay. 

For £50, it was worth the risk.

Anyway I took it apart and had a browse inside after discharging the tube.

I spotted 2 Diodes missing, they looked to be cut out intentionally, maybe used elsewhere, they were D704 Hitachi V09C and D705, Hitachi V06C. 

These are general purpose rectifiers dodes, luckily datasheets still exist online.

I found some UF5406 3Amp 1.7V diodes online to replace them, which I've just done. D704 feeds the Flyback transformer.
  
D705 looks like its the Flyback Diode handling voltage spikes and feedback when the transformer de-energises.

So far everything is working and I've tested with my CPC6128. Fingers crossed this did the job. The new diodes are overrated, but are doing the job required.

Now I need another project to repair/refurbish. Back to the web to browse for another project. 

Regards
Tibbs

[Bryce]

That's pretty nasty. The monitor could never have worked without them, so the seller took photos of a working monitor and then removed the diodes??

Bryce.

[tibbs1972]

Hello Bryce,

Yep, seems like the Diodes were removed or the vendor swapped it with another Monitor.

I've seen plenty of damaged circuits in my time, I don't think the Diodes blew, all was left was legs and no sign of other damage on other components, no Black marks, or any melted components.

I've attached the picture of it working from Ebay.

Luckily for them, I wanted to clean it up and refurbish it in any case. It gave me a bit more experience working with monitors as well.

Just glad I could fix it and that I could find circuit diagrams on the internet.

Regards
Tibbs

[tibbs1972]

Goods news this morning, after presenting the facts, I've been offered a refund and an apology, all's well that ends well.