| Electronics > Repair |
| Vintage chip Programmer : " Micropross ROM 3000U " |
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| Vince:
OK, just tried my computer monitor (LCD too), fourth and last monitor I have here. Deos the same as the previous monitor : does detect a signal but no picture because it does not like the timing. I says,in scary red background : " OUT OF RANGE ". So it confirms the diagnosis from the other monitor then. OK I will see if I can find a decent CRT monitor locally, and will get back to you ! >:D |
| pcprogrammer:
Hi Vince, it might be that the sync signals need to be inverted. And maybe they also need a resistor in series. Could not find the levels of them with a quick search. https://xess.com/blog/vga-the-rest-of-the-story/ Edit: And you will probably need a monitor that can handle the ~15KHz. It is basically old TV standard so indeed a CRT based monitor would do. Otherwise some upscale device can probably be found. Adrian's Digital Basement uses one. Regards, Peter |
| Vince:
Upscale device ?! didn't know about these things, thanks will keep that in mind :-+ Sync signal amplitude ? Yes I did think of looking that up because I wondered if tehy had to be 0.7V as well or not. They don't, they are considered digital signal so are meant to stay at TTL levels. HOWEVER you were right about polarity ! I forgot to pay attention to that, and indeed they are logic NEGATIVE not positive ! :scared: Let me invert them and see how we are doing after that !!! >:D Well not sure I will embark into that this evening.. .it's already 21H30 am getting tired and the 4 day long week-end is now over, I must resume work tomorrow ! :( So that might be rather for tomorrow evening after work. I could invert the signals using a couple transistors but I think using a TTL logic chip will be more tidy and compact. Stay tuned ! >:D |
| Vince:
Done. Was quick in the end. PIcked a 74LS04 in my stock, added that to the breadboard. Need a 5V supply for it... I have one handy ! Pin #8 that I thought was ground whch turned out to be +5V instead ! :-DD Well I now I am using it for what it actually is ! 8) Scoped my HV Sync signals, they are inverted properly and are clean. Monitor still complains as before, but well, it needed inverting no matter what ! OK so now the hunt for a CRT begins... |
| Vince:
Had a look for local ads.... many hundreds of screens within 20kms around me, incredible... but only 2 or 3 CRT monitors ! :scared: Found this one real close to me https://www.leboncoin.fr/informatique/2020623493.htm A few minutes drive away. 10 Euros (I offered 6 Euros via the website), says it works. A DELL, looks decent and although ad says nothing about model or screen size, it does not look too big which is good as I have zero space, my back is fragile and since we need it for very low resolution pictures, 14" would be plenty enough, so anything above that is already questionable... but you get what you can find, and this one looks overall OK. Sent the guy a message, asking if the thing is still available because... well the ad is a year and 3 months old ! :scared: |
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