Products > Test Equipment
Keithley 2306 Dual Battery Simulator Repair (maybe)
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ottobad:
So, C186 ( shorted ) is 4.98Vdc and now SRMA is at 5V BUT STILL IN INITIALISING ( don't know the value of C186 so is out from the board )
TP110 is ok, 5Vdc.
I will buy the SRAm and after recieve, will try again. :-+
Kean:
OK.  C186 is 100nF 20% 50V Ceramic per the list of parts in the manual.  I don't think the exact specifications are critical.
Let us know how you go after replacing the SRAM.  i hope that fixes it.

For your two isolated analog power supplies that read 0V on the outputs, check the input fuses F100 (marked FH100/FH101) and F200 (marked FH200/FH201)
They should read approx 12V (relative to the non-isolated digital GNDD) on both sides of the fuses, or should at least not be open circuit.
Smokey:
Hey guys.  Sorry for not getting back sooner on this.  I actually never fully updated what I discovered on my unit.

Firstly I have about 10 of the SRAM chips that I bought when I was first doing my investigation, but never used because that wasn't a problem I actually had. 
https://www.eevblog.com/forum/buysellwanted/fs-r1lp0408csb-5sc-4mb-sram/

Before you go swapping that, here is what I did that actually fixed my unit (at least made it reliable enough that it appears to work without any of the errors I was originally having).

Firstly, if I remember correctly, the "Initializing" on the display is actually coming from the display board.  So it's not some informative error message that the main processor is trying to tell you, it's just what the display board shows at power up when nothing else is talking to it.

Ok, so what I determined was the actual problem with my unit was a bad cap on the DISPLAY BOARD that was pulling down 5V for the rest of the system.  Unfortunately, the cap is between the display and the PCB which are soldered together with a lot of pins.  So instead of disassembling that, I just stuck a TON of extra capacitance on the top side of the display board 5V rails.  There are at least two unpopulated 5V cap footprints on that display board, so I stuck two 100uF 5V tantalums which I had around on those pads.  That gave the board enough capacitance that it no longer pulled down the 5V rail, and everything was happy after that. 

Hopefully that helps.

ottobad:
H :-//ello, thanks for the advice, I disassembled the display module, checked all the capacitors, they are good. I checked 5Vdc, all good. All that remains is to get the SRAM and change it... maybe that will fix it
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