Hi,
I've got my hands on one a few days ago. It is not working stable. It can be working for hours one day, but the other day it has one of the 3 behaviours:
1. Upon turning it on it continuously clicks relays very fast, buzzing actually. "Fail 1" on the display.
2. Upon turning it on it shows "Fail 1" on the display. No relay sounds.
3. But most often it seem to be resetting itself repeatedly in a matter of seconds to minutes. Sequence of action on the display is: OL, Fail 1, reset, normal. Relays clicking slowly meanwhile.
I have checked power rails, those are within specs and seem stable over time. I have not logged voltages, but I have measured on multiple occasions either cold or warm, good or failed state.
IC103 clock is stable.
I've got impression that it generates some signal on the HI input which causes overload or autorange fail. It can be vice versa of course. Autorange works normally when it is in a "good mood".
I have seen the following. Usually voltage fluctuates a bit (nothing connected). OL happens when the fluctuations go from last 2 digits to next one(s). I tried to catch it on the scope, it goes up to 0.2-0.7V when that happens.
I have read posts here about this model. I have not found any with similar symptoms. Elsewere out there too.
I would like to continue to debug it, but have not enough knowledge. Any advice, suggestions, ideas?
Schematics
http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Solartron/Solartron_7150/Solartron_7150_Maintenance_Manual.pdf. I have newer model from the two described, first power schematic from two.
Veiksmi,
J?nis