Hi all,
I've recently scored a Philips PM6303 LCR that was dead.
After some investigation, it looked like the CPU had died and, upon replacing that, I got signs of life from the meter.
However, the content displayed on the LCD didn't make much sense so, I thought maybe the display driver IC was damaged too (after all, it does have three lines coming from the CPU via some resistors).
So, I ordered a replacement LCD driver IC but, when testing the new one, I got the same display issues.
To see what I'm talking about, please see the attached pictures:
- the first one is supposed to have all segments turned on
- the second one is supposed to show a "6303" number plus some symbols and measurement units
Now, interesting thing that Dave has just decided to make some nice videos exactly on LCD's.
However, this one seems to be a multiplexed LCD and Dave is yet to cover that.
So, with not much understanding, I tried to troubleshoot this issue, but all seems to check out (i.e. BP1 and BP2 signals look like they should and there is data coming in from the CPU: CLB, DLEN and DATA lines have life in them).
What I wasn't able to confirm is what data is being received from the CPU (i.e. the value) or if there may be some data line syncrhonization issues.
Other than that, I did check the few passive components on the display board (some resistors and a couple of capacitors) and they appeared good.
Anyone has any suggestions what to check next, please?
Thanks!