EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: radiotek on May 05, 2015, 03:26:51 am
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Someone did some really sloppy rewiring on my ESI 250DE on the 1325 AC power pack. Ii looks like they added a resister to the output of the bridge rectifier. I still canb not believe that there was no filter capacitor after the bridge rectifier. I also measured the DC output voltage and it read 12 volts which seems a little high ? If anyone owns a ESI RCL bridge please contact me. It would be very appreciated if you could take a picture of your1325 AC power sully board so I could compare it to mine. Thanks, Frank
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Unfortunately no sites have schematics for the external ac power supply, here are some manuals
maintenance
http://www.ko4bb.com/manuals/75.140.215.49/ESI_250DE_Impedance_Bridge_Maintenance_Section.pdf (http://www.ko4bb.com/manuals/75.140.215.49/ESI_250DE_Impedance_Bridge_Maintenance_Section.pdf)
more
http://bama.edebris.com/manuals/esi/250de (http://bama.edebris.com/manuals/esi/250de)
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the power supply expects a set of Ni-cad batteries after it, these would normally act as the filter capacitors and a voltage regulator.
The resistor would be to stop the Ni-cads from overcharging.
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That explains why there isn't any filter capacitor after the bridge rectifier. Still the output voltage seems a bit high running at 12 volts but of coarse that is with no load and will probably drop down a bit under load. In my onion there should have had a safety switch so that the 1325 power pack could be isolated in case you wanted to use alkaline batteries.
Also wanted to mention that if the nicads are removed and someone plugs in the AC power cord there is a good possibly that the 12 volts coming from the 1325 power pack could damage the bridge.
Thanks for everyone's help.