Re: [volt-nuts] Dekavider DV411 repair and question
To everybode who answered: Thanks, so it was not only me not finding the leftovers of delimiters. Still curious why they made it that way. No reason to replace! Dave: I am aware of the resistor wire alloys like Konstantan, Manganin, Isabellin, Evanohm and their variants. What I didnt understand yet is the wiring between the resistors and the decades and so on - its just not simple silver-coated or tinned cooper wire, it more looks like a resistive wire - big and massive, bad to solder. Bill: Do I understand right, they use the inter-resistor wiring to for compensation ? (Your mail worked fine) Sounds like a bigger but reproducable resistance than wildly drifting cooper wire scheme to me. I try to figure out. The repair itself worked out very nice, the workplace 34401A in dcv:dcv ratio mode was happy with the results. BR Hendrik Hendrik, I didn't catch that you were asking about the interconnecting wiring. That is likely to be the same material as used to make the resistors (Manganin). That would maintain the low tempco of the total unit, and avoid the comparatively large resistance drifts of copper wire. Manganin is hard to solder without a flux that can remove the surface oxide that forms on manganin wire. Flux used for soldering stainless steel might be a good one to try. Just be sure to clean the joints very well after using it. The old ESI standards are very nice instruments to have. I have an old ESI decade capacitance box built like the Dekavider and Dekapot units. It's quite accurate; good enough to allow me to evaluate RCL-type multimeters. Cheers, Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
Hendrik, I didn't catch that you were asking about the interconnecting wiring. That is likely to be the same material as used to make the resistors (Manganin). Sounds plausible. That would maintain the low tempco of the total unit, and avoid the comparatively large resistance drifts of copper wire. As I wrote in my If I understand right message. Manganin is hard to solder without a flux that can remove the surface oxide that forms on manganin wire. Flux used for soldering stainless steel might be a good one to try. Just be sure to clean the joints very well after using it. Fortunately the previous owner kept the material when he modified it. The old ESI standards are very nice instruments to have. I have an old ESI decade capacitance box built like the Dekavider and Dekapot units. It's quite accurate; good enough to allow me to evaluate RCL-type multimeters. Besides that Dekavider which was part of a power supply i have a also recently ebayed SR1010 that was the cheapest to get and needed some TLC but the 34401A at work is not really a good instrument to check it, and i have my noble thing a Dekavider RV722 which I use quite frequently for ratio measurements, simply considering it ok for me as i was not yet able to show any problems with it (HP3456A and 34401A in ratio mode are both happy.) Cheers, Dave M Cheers Hendrik ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
To everybode who answered: Thanks, so it was not only me not finding the leftovers of delimiters. Still curious why they made it that way. No reason to replace! Dave: I am aware of the resistor wire alloys like Konstantan, Manganin, Isabellin, Evanohm and their variants. What I didnt understand yet is the wiring between the resistors and the decades and so on - its just not simple silver-coated or tinned cooper wire, it more looks like a resistive wire - big and massive, bad to solder. Bill: Do I understand right, they use the inter-resistor wiring to for compensation ? (Your mail worked fine) Sounds like a bigger but reproducable resistance than wildly drifting cooper wire scheme to me. I try to figure out. The repair itself worked out very nice, the workplace 34401A in dcv:dcv ratio mode was happy with the results. BR Hendrik ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
From: Hendrik Dietrich don_he...@gmx.de Subject: [volt-nuts] Dekavider DV411 repair and question Hi List, I partially fixed a lowly DV411 Dekavider from the Electro-Measurements epoque and wanted to report what worked out and what still is and have a general question about such devices. The part in question (just look what the cheapest one on ebay was, one made a power supply out of it) had a working first and second decade, but the can with the 3rd switch and last decade potentiometer required some work. The switch freewheeled, it didn't lock onto the right on-digit position. That was due to the slotted wheel slipping on the drive shaft out of position so it was no longer pressed against the spring-loaded ball. I was surprised that this wheel was just soldered to the drive shaft, so it was enough to push it back into the right position and solder it down with some very agressive flux (Soldeen-1). http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=locking_cogwheel.jpg The 4th(5th) decade potentiometer seems to be electrically okay, but it turns 360? instead of 270?, I consider that it had some delimiters but these are scraped off. However, careful operation will be possible or replacement by a potentiometer and a adapter between the thin driveshaft of the switch to the axle of a new potentiometer. (Hoped to keep it original.) http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=potentiometer.jpg For Pronographic reasons, a overview is available too. http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=overview.jpg Besides hints for further repair, does someone know which alloy is used for wiring by ESI? Seems a bit hard for plain cooper. Best regards, Hendrik Hendrik, It's been more than a few years since I had my hands on one of these boxes, but I aeem to remember that the vernier potentiometers in these instruments are designed to rotate a full 360 deg. I don't know why; seems illogical, but that's the way they are. If the original pot works, I wouldn't bother changing it. It will be extremely hard to find a replacement pot with the low tempco that the original pot has. The wire used to make the resistors in these units is probably Manganin, an extremely low tempco compound. Manganin wire has been used by instrument manufacturers for many years for temperature stable resistors. I think that most lab standard resistors are made with Manganin wire, and thermally insulated from the outside world to maintain their accuracy. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
Hi Hendrick, I agree with David M, I also remember the POT being a 360 degree turning pot. So, I went out into my storage shed to check the one I have out there and sure enough it is a 360 degree pot. As for the wire, you may find that they used different wire alloys to provide different positive and negative tempco's. Not sure what to tell you in that regard, except the less repair changes the better. BillWB6BNQ Hendrik Dietrich wrote: Hi List, I partially fixed a lowly DV411 Dekavider from the Electro-Measurements epoque and wanted to report what worked out and what still is and have a general question about such devices. The part in question (just look what the cheapest one on ebay was, one made a power supply out of it) had a working first and second decade, but the can with the 3rd switch and last decade potentiometer required some work. The switch freewheeled, it didn't lock onto the right on-digit position. That was due to the slotted wheel slipping on the drive shaft out of position so it was no longer pressed against the spring-loaded ball. I was surprised that this wheel was just soldered to the drive shaft, so it was enough to push it back into the right position and solder it down with some very agressive flux (Soldeen-1). http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=locking_cogwheel.jpg The 4th(5th) decade potentiometer seems to be electrically okay, but it turns 360° instead of 270°, I consider that it had some delimiters but these are scraped off. However, careful operation will be possible or replacement by a potentiometer and a adapter between the thin driveshaft of the switch to the axle of a new potentiometer. (Hoped to keep it original.) http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=potentiometer.jpg For Pronographic reasons, a overview is available too. http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=overview.jpg Besides hints for further repair, does someone know which alloy is used for wiring by ESI? Seems a bit hard for plain cooper. Best regards, Hendrik ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
