Hello!
I recently have obtained a non-working Fluke 1653 installation tester.
When switching it on I receive an Err 1 which means I shall send it to Fluke for repair.
Well, this is too easy and I started to investigate the problem.
I have a 2nd working unit of this installation tester available.
First I did an optical check and found a gold-cap (type panasonic EECEN0F204AK or similar) to have leaked on the front PCB.
I replaced it but still get the Err 1. The cap seem to be used to backup the internal RTC. Calibration values and saved measurements are stored in an external EEPROM.
Some say Err 1 means that the input protection may be broken, so I started to swap boards between the working unit and the broken one. I found the analog daughterboard (see attached photo) to be the cause of the problem.
With the board from the working unit the defective tester works fine, Err 1 is gone. So far so good.
Now I started to compare the supply and reference voltages on both units and all match.
The unpopulated connector P305 draw my attention and a quick check with my scope showed some kind of serial data - bingo (the pinout is added to the attached photo)
I connected a USB <-> TTL serial converter to these pins and captured some data from both testers.
The different outputs are quite obvious.
These messages might be some error flags from the defective board, but not sure:
{FTA00000004}{FTF}{FTL0000}{SID0000}{SB005A}{SR10001}{SR20001}{SH0001}{SIT002A}{SP10000}{SE30000}{UWP0000}{FTA00000004}{FTF}{FTL0000}{SID0000}{SB005A}{SR10001}{SR20001}{SH0001}{SIT002A}{SP10000}{SE30000}{UWP0000}0
I wonder if someone can help me to do some interpretation of the messages.
I suspect one of the analog switches (ADG711 [U320 & U319], ADG704 [U318 & U310]) to be the root cause but I don't want to replace them without beeing sure
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Any feedback welcome!
Best regards,
Bernhard