Got a TDR1502 (not working for parts) for small money some days ago.
I selected this against a (more expensive) working one, as the working had no cover and seemed to have been kicked around more. And a working one would lack the fun of repair...
First thing was removing the chart recorder. And it had ugly goo all around where once the rubber drum transported the paper
So I had to disassemble the whole chart recorder and clean up the mess. I
measuredestimated the size to 14mm diameter, so I ordered silicone tube with 6/10 and 10/14mm diameter to try a cheap repair first (I know a service that rebuilds rubber drums, but this is not the cheapest solution).
I dismantled the TDR and the dead PB battery was removed. After I found a dead capacitor, the unit powered up, but no backlight. Inverter was humming and I measured 0V after removing the display and let it run on the bench, so the EL foil is dead.
The rest seem to work OK, after cleaning I reassembled it.
Today I got the silicone tube and I cut one piece each and washed it carefully. After drying, I assembled the silicone to the shaft and trimmed it with a sharp cutter to the correct length. Reassembling everything, I assured the drum will transport the paper. Some gorilla had broken the knob to fix the module to the TDR, so I printed a replacement.
Installing it to the TDR and throwing the power switch, I waited for some magic smoke, but nothing happened.
So I used a
2m 6.56167979ft BNC cable and pressed the print button. Paper was slowly ejected...
So the only remaining problem is the backlight, will buy a new EL sheet and try to attach it to the display. Or I have to get a diffusor from a broken flat screen and try with LEDs.