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Is this a bad cap? (jenix DRO)

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  • #46
    SLK and gang --- I have some new news, I tried all kinds of things including Pauls suggestion of just a simple cleaning of the entire main bored yesterday along with soldering some connections I did not like that where done from the factory, still no change, the X scale has been the most recent culprit and like I say they "take turns" and it seems like once one dominates you can pretty much count on it being the one to act up ------------ all fingers did point to the scales but was hard for me to accept the fact that they both basically went bad at the same time although alternated but so it did start with the X, and when you swap the X with the Y read out the glitch does indeed go to the Y readout and you would think that verified the X scale...

    But ----------------------- I tried something very different this morning --- and yesterday after testing and being disappointed I just shut the DRO off and left it overnight,,, so today I had an idea, what if I swapped the X with the Y readout WHILE the DRO is off and sat overnight? what would happen? so I just got done trying it,,, the results? the X scale that is now showing on the Y readout is flawless, move the mills handle back and forth and instant registering --- then go to move the Y handle and the glitch is on the X readout, IT"S NOT MY SCALES and it's not the X readout either because remember when My Y scale would decide to act up it was connected to the Y readout and the glitch was there and the X scale and readout was flawless,,,,,,,,,,,,,,,, this is like I stated before almost like it's low voltage to run both scales and readouts at the same time and it just has to randomly choose one, and maybe that kinda gets locked away in some form of convenient memory glitch and repeats itself for the same scale and readout until you pull the old switcharoo when the unit has been shut down for awhile???

    This is progress - Im going back down to check the basic power boards voltage except this time im doing it while it's connected to the main board and under "load" meaning lighting up the display and everything

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    • #47
      I just ran the power board test and it appears its fine, no load and just testing the board I told you guys I had 5.08 volts and just now with load it reads 5.01 to 5.02 volts....

      the freakishness is in the main brain board or whatever you call it...

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      • #48
        Hey - back into the main board and hoping for a miracle ----------------- I found a resistor that isn't resisting,,, it's the blue one upper left corner, it's got nothing but an open circuit both ways (in case it was some kinda diode i checked) it's got a twin in the lower right corner and that one is instant response - I don't know what the numbers mean just was testing all random resistors and I get numbers except upper left corner blue one, could this be the problem? im going to try and find a duplicate in my computer stuff --- looks like it's one that goes to ground, same thing with it's twin...



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        • #49
          The Actel chip has a 2005 date code. The Dallas Semi chip is probably the same age. That suggests to me that the backup battery in the Dallas chip my be depleted, after 16 years of use, leaving it unable to store operational variables or data reliably. If nothing else works for you try to find the same Dallas chip with a newer date code.

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          • #50
            Originally posted by A.K. Boomer View Post
            Hey - back into the main board and hoping for a miracle ----------------- I found a resistor that isn't resisting,,, it's the blue one upper left corner, it's got nothing but an open circuit both ways (in case it was some kinda diode i checked) it's got a twin in the lower right corner and that one is instant response - I don't know what the numbers mean just was testing all random resistors and I get numbers except upper left corner blue one, could this be the problem? im going to try and find a duplicate in my computer stuff --- looks like it's one that goes to ground, same thing with it's twin...



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            Blue component is small value capacitor so its no suprise its not measuring anything on resistance range.
            Location: Helsinki, Finland, Europe

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            • #51
              Originally posted by genea View Post
              The Actel chip has a 2005 date code. The Dallas Semi chip is probably the same age. That suggests to me that the backup battery in the Dallas chip my be depleted, after 16 years of use, leaving it unable to store operational variables or data reliably. If nothing else works for you try to find the same Dallas chip with a newer date code.
              Wow --- there's a battery in the dallas semi-chip? you sound like you know your stuff thanks - what about that resistor? could it give fits or is it just there for surge protection or something (since its connected to ground)

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              • #52
                Originally posted by MattiJ View Post

                Blue component is small value capacitor so its no suprise its not measuring anything on resistance range.
                crap I think your right - now it seems it's twin wont give a reading and though it had

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                • #53
                  Originally posted by genea View Post
                  The Actel chip has a 2005 date code. The Dallas Semi chip is probably the same age. That suggests to me that the backup battery in the Dallas chip my be depleted, after 16 years of use, leaving it unable to store operational variables or data reliably. If nothing else works for you try to find the same Dallas chip with a newer date code.
                  15 years is stil probaby ok.

                  I’d connect the scales to the dro and measure all the voltage levels at the main pcb scale connector.
                  (supply voltage, Signal A low state and high state, signal B low state and high state.)

                  post the findings here for both X and Y and we can guestimate more.
                  Location: Helsinki, Finland, Europe

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                  • #54
                    Probably should not have been doing this but curious got the best of me - flipped the board over with the dallas chip in mind and could see at one corner the row of connectors last one looked like it went to a big ground block and the other opposing row opposite corner a power block as in leading to vast large area's for lots of stuff down the board to be soldered into - to i set my meter on auto volts and it picked up .009 volts... checked allot of the other connectors and they did not have anything... i better stop i don't know what im doing lol

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                    • #55
                      Originally posted by MattiJ View Post

                      15 years is stil probaby ok.

                      . . . .
                      I don't know the part number on this chip but I looked up a similar Dallas Semi SRAM chip and it specs the typical backup time ( power off time ) as 10 years. Granted, that's typical, not best or worst case. It's a long shot.

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                      • #56
                        Im pretty sure "hillbilly tech." has taken things about as far as he can handle,,, my original concern about the "build of the board" is really moot anymore also as I learned that there's little collars that are pressed into the two sandwiched boards so all's you have to do is have good connection on one side and it will get to the other - I did not know that until i looked very closely at part of the board that has options for other circuitry that are not being used and inspected the vacant holes and verified the collars...

                        If you guys come up with some easy tests i can make that are simple enough for me to take I will do so but even what Matt just suggested is over my head as I would not know where to start, thank you for all your help.

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                        • #57
                          Originally posted by genea View Post

                          I don't know the part number on this chip but I looked up a similar Dallas Semi SRAM chip and it specs the typical backup time ( power off time ) as 10 years. Granted, that's typical, not best or worst case. It's a long shot.
                          I have replaced few bad Dallas SRAM's but those were closer to 25 years old. Overall pretty much trouble-free part considering there is a tiny battery inside.
                          Even EPROM's seem to corrupt more often and flash/EEPROM problems with some equipment are more of rule than exception.
                          Location: Helsinki, Finland, Europe

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                          • #58
                            every time I think I got it --- I don't, but who knows this might help you guys,,, so looking into the units lead connections from the scales I did notice something suspect so undid the leads holder from the back of the box, I looked up close with my magnifying lens and it looked like the center "chassis ground" (big green wire with yellow stripe along with little green connector that goes to same center pin on other axis) wire was contacting another lead, I tested this on the pin side and sure enough it was!!!
                            upon closer examination it looked like it was the pin to the boards ground wire (black) that it was connecting with and since that ends up going to the chassis ground anyways maybe it does not matter - But - it also it seems to do so through the boards resistors so could be important to have them separated and in fact they must have them separated for a reason ???
                            anyways --- I had to take a razor and cut through the nub of solder that was not connected to the black pin wire but protruding enough to rest against it and i just shaved it all down --- reassembled the entire unit to try and no change,,,,,,,,,,, im burned out once again and going to go buy some beer... Click image for larger version

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                            • #59
                              Probably not the Dallas NVRAM chip. If it was bad it just would not remember settings when you turn it off.

                              My guess is you have a bad IC someplace. You might just want to get a new head unit to use with your old scaled. Unless you have an oscilloscope to start digging in there.

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                              • #60
                                You might want to check if the suspect scale axis works better/worse when the reader head is cooled down or heated with hot air gun.

                                If the opto is borderline working the symptoms get worse with increased temperature.
                                Location: Helsinki, Finland, Europe

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