I've recently purchased an '88 coupe. The mechanics and body are sound but interior and electronics have needed lots of attention.

When I bought the car the cluster was really dim, flickered on and off and sometimes random segments would light up. After combing the other cluster posts and Batee sight I've changed the bulbs, cleaned all pins and connections, installed a new ground and gone through the Batee bench top testing process. During all of the tests the cluster works great. It fully illuminates when turned on and I can change between all the different display options.

My problem is this, 1 to 2 minutes of use/testing the voltage display comes on, then beginning at around 12V it climbs to around 17V and then the cluster goes black.

My only other pieces of information are that the dimmer isn't working and I've replaced the light bulbs with LEDs.

Any advice on what to try next would be appreciated.

 

You mention doing the bench tests etc but a bench test is generally a "quick check" more or less and not a durability/reliability test. I'd think I'd look further into a power supply problem and maybe a bench check of the cluster supplying known voltage powers and maybe random increases of that voltage until maybe you can create the situation in the car.

I'd likely scrap the LED's and trouble shoot with known good and reliable product.


1st step I'd think - LED's to the trash.

 

There is a power supply on the cluster. You may want to look in to that. It's an easy change if you can do some minor soldering.

 

Thanks for the replies,

The LED's are out and I've got Halogen bulbs in there now. Interesting note, I got the same voltage readings with both sets of bulbs.

Following the Batee steps on the link below I've looked into the 8 pin connection between the power source and main board, I used the sites reference so 1 is on the bottom and 8 is on top if the cluster is upright and your looking at it from behind. This is what I found.

http://www.batee.com/corvette/dcrg/power_supply/

When cluster is illuminated and working pins 1 and 6 have 4.7V between them, after it shuts down (mysteriously and by itself) the voltage goes to 0.3V. So when lights are on the power source is working and when lights are off its no longer working?

The AC voltage between 1 and 6 always reads 0. However, my metre isn't sensitive enough to measure mV so this data doesn't help too much. Therefore the filter capacitors may have failed. Does anyone know what these look like?

Pins 1 and 3 have a similar drop going from 5V while working to 0.4V after the shut down. My guess is that this sensor is what causes the seemingly random shutdown?

Pins 1 and 2 consistently read 0V between them. Batee says that this indicates failure in the standby voltage regulator. Does anyone know what that looks like?

My goal here is to pinpoint what components of the power source aren't working. I don't feel confident replacing them but if I could take it to a shop and ask for specific things to be replaced it would be way cheaper than shipping it away.

Any ideas for next steps? If I was able to identify each part of the power source I could point to the exact component that needs replacing.

 

I thought that Batee offered up a description and an image of each component of the power supply. Using your link I clicked on power supply repair kit and ended up with this:

http://www.batee.com/corvette/dcrg/services/pskit.html

Each part is identified and I would think there would be no issues with a local shop ID'n each component.

Maybe borrow or buy another DMM

 

There is a photo-cell that detects light and shuts off the dash lights when it detects darkness. In my case I thought it would be easier changing out the power supply instead of the handfull of parts that were the usual culprits (I was in a hurry).

 

The dash uses PWM (Pulse Width Modulation) to adjust the brightness of the back light bulbs (or LEDs). It doesn't matter whether you have bulbs or LEDs in there. See this link for WAY more info about dash backlighting than you probably want to deal with:

https://www.corvetteforum.com/forums...ull-story.html

They are the black cylinders in the batee photos.

That would be the 2N4403 transistor in the center of the power supply schematic.

To do that you would need to test to verify that a part is bad. Do you have the expertise to do that? From your questions I would guess no. If you're not an engineer, electronic technician or otherwise have knowledge of electronics I would say the odds are slim that you could identify a bad component.

 

Okay, I'll admit to being out of my depth here. I've put so much time into figuring this out I wanted to see it through to the end. I've ordered a new power supply and will have it soldered on when it arrives (hopefully before the weekend). In the meantime I need to pray to the Vette gods that this is the actual issue.

Thanks all for your support, its good to know there are others willing to share what they know.