dave97

I have a 98 C2S with a tach that has OBC display. It has started to act up. It stays lighted, but the display goes to unrecognizable digits. It can then switch back to legible. When it goes out changing the mode doesn’t make a difference. I have read that the later models don’t have the transistor. I’m not sure if the transistors fix is just for dim or out lights. Could it be the LED screen? Thanks. Dave

TheBen

Call north Hollywood speedometer and see what they say.

ToreB

This is a typical failure in the LCD or its connections, and indeed fixable.
Cheers,
Tore

bb964

I had mine fixed by Palo Alto Speedometer and here is a DIY that might help 911/964/993 OBC TACHOMETER

geolab

Fixed mine by giving it a big slap when it flickers with palm of hand

else:

https://rennlist.com/forums/993-foru...-repair-2.html

pp000830

I have not opened one of these up on our cars but I have serviced segmented LCD displays.
If the display is intermittent but seems to work properly some of the time, the display itself is probably OK. I would inspect the connector to the display and maybe clean it with some electronic spray cleaner.
If it is a ribbon connector I would detach the ribbon and clean the ribbon end and its socket and reassemble it. After 25 years of heat cycling and atmospheric humidity, the connector can have issues. While you have things open check for cold or broken solder joints and you may want to consider replacing electrolytic capacitors you come across.
Andy

Porsche-ah

I give it a flick with my finger when it happens to mine and it goes right back to normal (Been this way for the last 10 years lol)

Knight

Somehow the tap on the OBC has done the trick for me to the last 5+ years