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| | |-+  No 5Vdc at chip in EZ command unit
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Author Topic: No 5Vdc at chip in EZ command unit  (Read 893 times)
abe

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« on: July 29, 2009, 08:26:06 AM »

Hi,
I have an EZ command unit and it does not work. I have measured that there is no 5 VDC at the vdd input (pin 20 of the micro chip). The power supply input to the unit is fine. I think it is some were in the 5Vdc line that the problem lies. Does anybody have a schematic of the EZ command station? Has anybody ever has such a problem and found a way to fix it?
Let me know.
Thanks,
Abe
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #1 on: July 29, 2009, 10:16:18 AM »

Three thoughts immediately come to mind:
Blown voltage regulator I.C.
Unit is turned off (stop mode?)
Wrong reference.

I was going to add 'wrong pin,' but I assume that you have checked the pinout for the I.C. and know how to count pins.

With no schematic available, your best bet is to follow the +5 line back to its source and see where the loss is.  Marking the traces with a fine tip felt pen, preferably red, helps.  So does taking photos of both sides of the board and making enlarged prints.  Tape or glue them back to back and aligned.  Then do your tracing on the photos.

Jim
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