UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Nascom repair

SiriusHardware · 4th Nov 2017, 10:56 am

It looks like you're back to trying to write some test code, or 'belling out' every single interconnection on the PCB in case the fault is a physical fault like a cracked track or failed through-hole connection. Not a task I would relish.

Some EPROM programmers of a certain vintage have an 'eprom emulator' mode where they provide a connector for a flying flat ribbon cable with a male DIL connector on the end of it: This plugs into the target system's EPROM socket and the EPROM programmer uses internal RAM to emulate the action of an EPROM, the advantage being that it only takes a few seconds to download altered / amended code to the programmer.

If your own programmer(s) had this feature I'm sure you would already be using it, but it might be worth looking out for an old programmer with this feature. I have one unit which is a serial hex -> eprom emulator only, not a programmer, made by a little outfit called 'JPD' many years ago, and I also have a commercially made EPROM programmer made by ICE TECH which includes an EPROM emulator feature. There surely must still be a few of these around.

You'll still eventually need an eraser of course: I wonder if you can now get UV LEDs which produce light of a suitable wavelength? My understanding is that some LEDs used in LED lighting actually natively emit UV, and they are coated in phosphor which converts the UV light into light of the required visible wavelength. Is anyone already working on a LED eprom eraser?

4th Nov 2017, 10:56 am	#24
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,548	Re: Nascom repair - Looking for clues please It looks like you're back to trying to write some test code, or 'belling out' every single interconnection on the PCB in case the fault is a physical fault like a cracked track or failed through-hole connection. Not a task I would relish. Some EPROM programmers of a certain vintage have an 'eprom emulator' mode where they provide a connector for a flying flat ribbon cable with a male DIL connector on the end of it: This plugs into the target system's EPROM socket and the EPROM programmer uses internal RAM to emulate the action of an EPROM, the advantage being that it only takes a few seconds to download altered / amended code to the programmer. If your own programmer(s) had this feature I'm sure you would already be using it, but it might be worth looking out for an old programmer with this feature. I have one unit which is a serial hex -> eprom emulator only, not a programmer, made by a little outfit called 'JPD' many years ago, and I also have a commercially made EPROM programmer made by ICE TECH which includes an EPROM emulator feature. There surely must still be a few of these around. You'll still eventually need an eraser of course: I wonder if you can now get UV LEDs which produce light of a suitable wavelength? My understanding is that some LEDs used in LED lighting actually natively emit UV, and they are coated in phosphor which converts the UV light into light of the required visible wavelength. Is anyone already working on a LED eprom eraser?