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| HP 5335A Timer / Counter - Anything i should know? |
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| David Aurora:
Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work. Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work? |
| Dr. Frank:
--- Quote from: David Aurora on May 24, 2023, 08:59:07 am ---Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work. Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work? --- End quote --- Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval. |
| David Aurora:
--- Quote from: Dr. Frank on May 24, 2023, 09:43:04 am --- --- Quote from: David Aurora on May 24, 2023, 08:59:07 am ---Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work. Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work? --- End quote --- Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval. --- End quote --- Thanks for confirming! Back to the naughty shelf it goes until I find another IC |
| Dr. Frank:
--- Quote from: David Aurora on May 24, 2023, 09:52:59 am --- --- Quote from: Dr. Frank on May 24, 2023, 09:43:04 am --- --- Quote from: David Aurora on May 24, 2023, 08:59:07 am ---Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work. Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work? --- End quote --- Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval. --- End quote --- Thanks for confirming! Back to the naughty shelf it goes until I find another IC --- End quote --- Better search for a front end replacement, as this IC might be unobtainium. This double channel electronics was identical to another HP 500MHz counter, I just don't remember the model No. This other, elder counter was quite cheap to acquire. |
| David Aurora:
--- Quote from: Dr. Frank on May 24, 2023, 11:16:57 am --- --- Quote from: David Aurora on May 24, 2023, 09:52:59 am --- --- Quote from: Dr. Frank on May 24, 2023, 09:43:04 am --- --- Quote from: David Aurora on May 24, 2023, 08:59:07 am ---Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work. Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work? --- End quote --- Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval. --- End quote --- Thanks for confirming! Back to the naughty shelf it goes until I find another IC --- End quote --- Better search for a front end replacement, as this IC might be unobtainium. This double channel electronics was identical to another HP 500MHz counter, I just don't remember the model No. This other, elder counter was quite cheap to acquire. --- End quote --- Yeah, I'll keep an eye out for whatever I can get to button this thing back up I guess. IC's, whole boards, junked units, other units with the same part, whatever pops up first and gets it working again :-// Frustratingly I didn't even really want it but grabbed it because I'm always loaning gear to people and thought another counter couldn't hurt. But I think by the time I sort this out I'll have pumped far more effort into it than it was worth :-DD |
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