Chrysler Repair: 89 New Yorker digital display, electrolytic capacitors, electrical circuit

Question
Roland,
I have a 1989 New Yorker with the florescent digital display. Recently the dash has begun to buzz when I turn on the key. I suspect it may be some sort of chopper in the electrical circuit that supplies power to the segments of the display. I have a feeling it may fail which will cause the entire dash to fade and finally go blank. The buzz sounds like it is coming from the left side of the main speedometer display inside the dash. Do you know where I might get an electrical schematic for the speedometer electronics or do you have any knowledge of what may be causing the buzz? Anything you can pass on will be greatly appreciated.
H  

Answer
Hi Harry,
There is no circuit diagram shown for the clusters in the manuals. About the best I can suggest would be to remove the cluster and while still connected you should be able to find what is buzzing. I would look at any of the electrolytic capacitors as the most likely to fail components. There is company in Canada that rebuild clusters called Crescent Electronics at 519-972-0667. Best of luck on getting to the bottom of the noise.
Roland