Infocenter disco mode

[Fietsaapje]

Hello everyone!

I am new to the board so i will introduce myself a little bit:
I am from Utrecht, the Netherlands and since last may i am the proud owner of a 1992 volvo 480es with 1.7l engine. Driving it has been great so far but now i am running into some troubles with the infocenter

Instead of useful information a random amount of segments will flash with an interval of about 1 second. Sometimes the segments that flash will change. I will add a video that i made today of the problem. Around 15 seconds you can see the changeover to a different set of segments.https://youtube.com/shorts/Gw_P3VXZx-M
I am fiddling with the selector switch because that seems to sometimes trigger the changeover. However it also happens at random times without me touching anything.

At first the problem would sometimes occur for 5 minutes and then resolve itself, but now for about a month it is permanent from the moment i start up my car in the morning.

Things i have tried to solve the problem:
- Resolder the infocenter green pcb. It had some dry joints.
- Open up the lcd unit and clean the rubber contact and pcb contacts that press on the strip (i only cleaned one side of the strip because it seemed to be glued on the other side?)
- Put a piece of paper for extra pressure on the contact strip.
- Clean the 5 pins that transmit info+power to the lcd unit.

However today after doing all that the problem is still around.

Does anyone have a clue what is going on and if there are other things i could try to solve the problem?
I can do soldering and have a oscilloscope + multimeter at hand to test stuff.

Thank you for reading

Fietsaapje

[WRDendy]

Does look a lot like a bad connection on the zebra connector - it does come apart completely, see pic of one currently on my desk:



Joints on the board and isopropyl alcohol on the zebra and LCD, although it sounds like you know what you're doing on that front!

Failing that, could be something wrong with the main PCB on the back:



Same faultfinding procedure applies, although I've had more luck by just replacing them.

[Fietsaapje]

Thank you for replying and for the picture
I think by "replacing" you mean replace the whole cluster? Sounds like a safe option but sadly this seems pretty hard to do at this point. I can not find a single unit for sale online
I might open her up again this weekend and attempt to resolder everything i haven't done yet, and also clean both sides of the rubber strip this time.
If this does not help the problem i can maybe attempt a measurement of the data pins. I found a really interesting project of someone who reverse-engineered the whole computer in order to fit it in a volvo 460: https://thomas-hardwaredesign.de/bordcomputer-projekt/. I think his explanations can help me do some more advanced fault finding using my oscilloscope.
If anyone else has had experiences with these kind of display faults i would still really like to hear about it!

Thanks, Fietsaapje

[WRDendy]

Not the whole cluster, just the PCB in the second image. Very unlikely to find one of those for sale either, however forum member Brinkie (a fellow countryman of yours) might well be able to help.

Also long shot but try cleaning up the info centre switch (or leaving it unplugged completely) - if the contacts are dirty it can cause confusion as well.

[jamescarruthers]

Hello Fietsaapje!

You are lucky that Brinkie on here is in the NL and hopefully able to help you out. Do you know him already as he is in the Dutch 480 club?

[Fietsaapje]

Good call WRDendy i will make sure the selector switch is working properly.
I have seen the legendary Brinkie give his expert advice throughout the Forums. This is my first post and i am not (yet) member of the Dutch club therefore i haven't spoken to him yet. Let's see if he finds this post

[brinkie]

Fietsaapje (which is Dutch for bicycle monkey ), I am living in Houten, just 10 km from your place and I have both profound knowledge of the 480's electronics and a large stock of spare parts. Orlando lives just 40 km further if there's need for more spares. You are cordially invited to take your 480 to my place on a Friday morning or Saturday afternoon, coffee/tea/beer is complimentary. Taking the cluster out and back in again will most definitely take longer than the fix itself.

[Alan 480]

Fietsaapje (which is Dutch for bicycle monkey ), I am living in Houten, just 10 km from your place and I have both profound knowledge of the 480's electronics and a large stock of spare parts. Orlando lives just 40 km further if there's need for more spares. You are cordially invited to take your 480 to my place on a Friday morning or Saturday afternoon, coffee/tea/beer is complimentary. Taking the cluster out and back in again will most definitely take longer than the fix itself.

well you cant argue with an offer like that?
this is what makes a forum useful, all trying to help each other

[Fietsaapje]

Wow Brinkie thank you for the invitation! This is probably the best thing that can happen to a person with Info Center troubles . I will do a final fix attempt this weekend and if the problems persists i will gladly come over!

[brinkie]

If anyone else has had experiences with these kind of display faults i would still really like to hear about it!

For the record: this problem is most probably not caused by faulty electronics, but by a faulty connection between the computer and the display. Communication takes place using 5 pins which carry +5V and GND for power supply, a clock and a data pin (I forgot which function the fifth pin has). If communication is disrupted, the display freezes or starts displaying values in Klingon.
It is usually fixed by both squeezing the 5 sockets of the display connector a bit with a set of small pliers and reflow the soldering of the print connector of the infocentre computer. As a preventive measure, you can also replace the electrolytic capacitors on the infocentre board.
I have repaired over 100 instrument clusters and have encountered only very few defective infocentre computers (display will be dead) and 1986/1987 displays with red stripes have a tendency to break, but then parts of the display will be dead.

[Fietsaapje]

Those are some interesting details Brinkie, thank you . According to this website: https://thomas-hardwaredesign.de/bordcomputer-projekt/ the 5th pin is for a 18.5kHz PWM signal that drives the LCD segments (they work on AC). He says it is also used to "switch registers" within the LCD driver but i don't know why that would be necessary. However, good to hear we can probably rule out a defective computer as the display is still very much alive.

[Fietsaapje]

Well well. To start off: it is not fixed yet.

Last weekend I once again opened her up and attempted the following:
-Clean both sides off the lcd zebra strip + respective contacts of the screen and pcb.
-Resolder the whole LCD PCB.
-Resolder the 16 pin connector on the main computer pcb (other side has already been done 6 months ago)
-Found that one of the 3 capacators was bulged on the bottom and leaking: replaced them all with new 100uF 16v caps (i somehow still had new ones laying around).
-Checked the selector switch and ran the computer without it to be sure.

However as i just said, no change in the behaviour whatsoever
Last week i even caught her showing the correct water temperature, even if it was for only 5 seconds. Still confirming that there is life in there. Somewhere.

Guess i'll have to take it up with mr Brinkie sometime soon