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Topic-icon '88 r100rt Electrical Problems (New owner)

  • tomkilde
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2 months 2 weeks ago #4937 by tomkilde
Talking about electrical problems, do you have any suggestions for troubleshooting an uncooperative instrument panel? I'm about 99% done with a ground-up restoration of a naked '83 R80RT I bought last fall. I started the engine for the first time about a week ago, and everything seems to be working well except for the instrument cluster. The tach and speedo light up, and the oil pressure light works, but that's about it. The other indicator lights will not light up - I checked the bulbs, but they are good. Also, the tach will sweep around to the pin when I turn the bike on, but then the needle stays there and won't return. I took the cluster apart to check the bulbs and clean the glass, and everything inside appears to be in good condition, at least visually.

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2 months 2 weeks ago #4939 by Wobbly
Replied by Wobbly on topic '88 r100rt Electrical Problems (New owner)
Welcome Aboard !

Three things come to mind....
• First, disconnect the connector on the rear of the instrument cluster. While inserting an electrical test probe into the various sockets you should detect 12V on the various pins at the correct time. (The pin-out for the connector is given on the various schematics available on-line.)

Also, it is important to check the quality of the Return (what most people call Ground) contacts. When ever multiple lights or features fail... think "faulty return wiring". You can use the same test lamp, but this time connect to the battery Positive.

• The socket-to-pin contact has to be good. I'm always wary of that large molded connector. It wouldn't hurt to have a tiny dab of No-Ox-Id inside each of the sockets.

• Since the pins are made onto the flexible circuit board within the instrument cluster, that only leaves the flexible circuit board itself. The older boards are bad to break off right at the lamp positions. The circuit board is supposed to wrap down into each bulb position. The very small piece that makes that right angle transition into the hole is bad to break off so cleanly that it looks normal, but it won't make contact with the bulb holder. When that happens you need a new flexible circuit board. Luckily those are made by a 3rd party now, and have up-graded surface mount LEDs in place of the bulbs. See.... katdash.com/

Hope this helps.

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2 months 1 week ago #4951 by tomkilde
Replied by tomkilde on topic '88 r100rt Electrical Problems (New owner)
Thanks Wobbly. I broke out the multimeter and did some basic tests. No issues at the fat plug. The instrument cluster is a different story. At the working lights, the little copper tabs are OK and I get good continuity across the circuits. At the non-working lights I found two broken tabs (you can see one in the attached photo), and little to no continuity across the circuits. Not even between the pins and their corresponding tabs. Visually the printed circuits look fine, but something is definitely not right. Looks like I'll be placing an order with Katdash!
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2 months 1 week ago #4952 by Wobbly
Replied by Wobbly on topic '88 r100rt Electrical Problems (New owner)

tomkilde wrote: Visually the printed circuits look fine, but something is definitely not right. Looks like I'll be placing an order with Katdash !


And that's really the best idea because the Katdash unit does away with the bulb holders AND bulbs.

Glad to be of assistance.

Don't hide 'em, Ride 'em !!
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