348 Speedo Burned Internals

Wade, the color bands on the resistor were Blue, Gray, Gold, Gold. That equals 6.8 ohms with a 5% tolerance. HTH.

 

I took a ton of pics of the board in my speedo while I had it apart looking for a problem, thanks to posts I've seen here where people were unable to identify burned components after the fact. Glad it was of some help to you.

I wonder if there's an intermittent wiring problem somewhere that's causing your speedometer to toast itself...

 

Guys,

On these old boards, often time the root cause are leaking/shorting/failing electrolytic caps. You should examine them for bulges, leaking electrolyte and even if not found desolder these, check capacitance and replace, maybe with tantalum ones. Hopefully there are not a lot ones to fix/change and good news are once you do this you are good for another 25-30 years ;-)

 

Excellent advice, Bart! This is true in vintage audio components and cars typically endure harsher conditions. Caps are cheap and easy to replace, so why not?

 

Wade, I went through the shots I have and created a zip file that will hopefully provide a complete component list with the exception of two components. There is an electrolytic cap mounted horizontally and its values happen to be on the bottom, against the board itself, so I couldn't read those even with the board in my hands. There is also a red device that looks somewhat like a ceramic cap that is near the resistor that burned. I think there's an image of all of the identifying marks on it but I'm not sure since they don't mean anything to me. If you can post values for either or both of those components I'd like to have them for my records, as well as for the archives.

I also included a couple of shots of the "mystery part" I found inside the rear housing of the speedo as I went to reassemble it, in hopes you'll be so kind as to examine yours to see if you can tell me where it goes.

The pics are probably not all that useful in 800x800, although I may try resizing them to see if they'd work for the archives. So I put the full res versions in my Dropbox and will leave them up for a while, but they likely won't there permanently. Here's the link: https://db.tt/jIp5pSgA

HTH,

///Mike

 

In case they might be useful to someone in the future, here are some shots cropped & resized.
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A few more...
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And the "mystery component", in hopes someone can tell me where it goes, assuming it even belongs in the speedometer.
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I've learned so much from this forum it's a pleasure to have the opportunity to contribute.

Just wish I'd made the effort to light the shots better. Will try to do so next time. I'm not a photographer by any means. At least the full size versions can be blown up to provide better detail, so by all means grab those if you want.

 

Here's a more or less comparison shot to your bottom pic. The main difference I see is that you're a far better photographer than I am.
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What is written on your red cap(?) next to the black connector?

 

What's embarassing is that I have a decent camera. I was just too lazy to set up any proper lighting and the overhead can lighting was blocked by the camera. I could see some of that on the camera screen so I grabbed the LED work light that happened to be lying there, which helped but totally screwed color rendition.

Fortunately, between your shots and mine I think we have values for all of the components except the red thing. Sourcing some of them may be another matter entirely, but having the values in the archives is a good thing.