I just read your post again and missed that you reflowed the solder joints. I will have to stop reading posts with my phone.
Todd On Wed, May 20, 2015 at 3:52 PM, Todd Micallef <[email protected]> wrote: > Frans, > > I had two 3458a fail that resistance cal. I eventually replaced the > front / rear switch. The easy way to test it is to measure the resistance > with the front panel jumpered and then short the internal black and white > cables at the A1 board and measure the difference. I also had one with a > bad cable in addition to the switch. The cables develop small breaks just > behind the crimps. Wiggling the cable showed how bad it was. Both were > available for order the last time I needed them. > > Todd > > > On Wednesday, May 20, 2015, Electronics and Books via volt-nuts < > [email protected]> wrote: > >> my 3458 was getting troubles with the calibration of the zero. As volts >> where no problem and ohm were pretty accurate, my conclusion was that there >> is basicly nothing wrong. the calibration stopped at the ohm-10. so it must >> be in the sense lines somewhere. on de dc print there where 2 big resistors >> (Dale ?) in the sense lines. with a magnifying glass i could spot litle >> cracks in the solder. after heating with some fresh solder the fault was >> over. >> >> i have red several times that the standard resistor for ohms should be of >> a better type. In my 1998 production unit it is a vishay vhp101 40k. that >> must be one of the better ones that were made by vishay. in an older 1994 >> unit there was no brand or recognisable type code on it. >> >> Regards >> >> Frans >> >> >> [email protected] >> Netherlands >> >> Discere ne cesses >> _______________________________________________ >> volt-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
