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Thread: How to burn 2708s

  1. #81
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    I wonder why the extra VR was left out then.. hmm. Back to the documentation.

  2. #82
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    Ok so the 7912 is there for power supplies that are 19v, 'like the Smoke Signal Broadcasting 6800'. Since mine is a stock SWTPC and I don't believe the MP-P psu is 19v, I think this is ok.

    Info on the H/V switch is maddeningly non-existent. There is no mention of it whatsoever in the manual. The only thing that possibly refers to it is a brochure for the card, where it talks of a 'safety switch from the high voltages generated'. So I'm wondering if the 'is HV on' prompt is an instruction to flip the HV or high voltage switch, to begin programming. Kinda makes me a bit nervous given my 6800s age. Maybe I want to have a fire extinguisher handy?

  3. #83
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    Okay yeah, you need the HV switch on. I did that, and it definitely worked. Sort of. I got hard errors from 0130 to 013F. I verified the contents of the rest of the chip and it all looks good. For 0130-013F, the second digit for each byte were all 0s. So for example 68 would be 60, A1 would be A0. I'm going to try erasing again. I think the programmer is working ok, but maybe this old 2708 is hooped.

  4. #84
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    Dunno--I'd think that if you managed to erase the chip to all FFs, it wouldn't seem as if a bit would spontaneously flip to 0.

  5. #85
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    Yeah I think I goofed. On going through the burning software more, I realized when I had done the Erase test, it had been warning me that some addresses were not FF. So I will attempt another erase and try again.

  6. #86
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    If the 2708 won't fully erase, it's time to bronze it and use it as a tie clip. Or something, but not as a PROM.

  7. #87
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    Yeah. I tried with the eraser again last night.. but it's the same thing.. the burner software reports that 0130-013F is still not FF. Strange that it's a neat segment like that.. not like, 0130-0133 or 0136-013A.

    I'll try one more time with the eraser. Otherwise, I guess we gotta buy another.

  8. #88

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    Make sure the window is absolutely clean. If it is a clear hard quartz, I often use a dull knife to scrape it clean. If it is the frosted cover, you have to use cleaner, like googone.
    Dwight

  9. #89
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    Yeah I gave it a really good cleaning. There wasn't any tape on it from what I could see. I ran it in the eraser again and initially it looked good.. all FFs.. but when I switched on the high voltage and did another erase test, same addresses were wrong again. I don't think it's my burner, although without another 2708 it's hard to be sure. I'm looking for another one and we'll see what's what.

  10. #90

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    Actually, now that you mention it, it sound more like a problem in the programmer than the EPROM. I was thinking, what a strange failure for the EPROM. It wouldn't be all that strange if it were the programmer.
    Dwight

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