Burnt trace? No idea what I am doing.

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Old 05-10-17, 06:23 AM
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Burnt trace? No idea what I am doing.

Trying to trouble shoot a bad speedometer in a 93 Toyota pickup 3VZE engine with auto and no speedometer cable.

Is this a burnt trace and if so is it repairable? IS there something else I should be looking for that caused it to burn?

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  #2  
Old 05-10-17, 06:36 AM
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Yes, it looks like a burnt trace. It could be repaired by bridging with a wire, but traces don't burn without some root cause, and fixing that trace likely won't solve the problem.

Anything else on the board look like it's been getting hot?
 
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Old 05-10-17, 07:51 AM
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Thanks for the response. I do not see anything that looks burnt. Would an electronics guy be able to test this and know what is wrong and fix?

I am out of my element here, I'm lucky I found the burnt trace, so don't have a clue and any input appreciated.
 
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Old 05-10-17, 10:54 AM
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What components are in the burned trace area? What components are connected by the burned trace? A burned trace is relatively easy to repair or install a jumper wire. Damaged components can be tougher as simply identifying the bad component can be difficult to impossible. You won't find a schematic for the board and most these days don't label what each component is so the only way to identify a component is by looking at it. If the heat damaged it's markings identifying it could prove difficult/impossible but if the board is toast already there is no harm in sticking in your best guess component and see if it works.
 
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Old 05-10-17, 11:30 AM
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Under the black circle is what looks like a transistor. That should be checked. The red line is the the power buss but from such a small view there is no way to tell its travel direction.

There is definitely a shorted component. The foils will not burn by themselves.

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Old 05-10-17, 02:11 PM
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Thanks for the input, greatly appreciated. This all above my pay grade and would not attempt a repair myself, can this be done by any electronics person or does it need a speedometer specialist. I contacted a speedometer specialist and his estimate is $150 for the repair. Is that an ok price or way out of line? I cannot find a used one local.
 
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Old 05-10-17, 06:07 PM
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The $150 estimate to repair an instrument cluster is pretty much a standard price.
Guys I know charge the same here.

I had a mobile electronics store for many years and if someone brought that to me I'd check it out for them. A lot of the parts used are unlabeled which makes repair more difficult. If it turned out that a meter movement/motor was shorted... that was an additional problem.

I'd recommend bringing it to the shop.
 
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Old 05-10-17, 06:49 PM
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That really does not look burnt, it looks almost corroded. And if it was burnt, it definitely would NOT be from a short. A short would've blown the thinnest part of the trace right off the board, which has not happened. If ANYTHING it would be an overload, which would heat the board up - but there is no discoloration on the north side of the trace. All of the discoloration is in that one etched area between the trace in question and the one below it.

Can you get any clearer and closer? If your camera has a Macro setting (the "Tulip" symbol), use that.
 
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Old 05-10-17, 07:45 PM
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Not easy to get a good close picture, this is the best I could do.

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Old 05-10-17, 08:03 PM
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Good pic. Several issues there. Can you post a pic of the other side....same area.

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Old 05-10-17, 08:34 PM
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CAnnot get a full picture of the other side, here is a view from the top which shows components where damage is.

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Old 05-10-17, 10:20 PM
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Ok... that's just the speedo board.... I thought it was the full cluster.
$150 for that repair would be on the high side.

Your pics are perfect.

I updated my picture so as not to add any more pics to the thread.
I labeled two parts.... C for capacitor and V for varistor (transient surge absorber).

Confirm that the foil is actually burned and not corroded.
I'm fairly certain that the varistor is shorted or is drawing an excessive amount of current and that is what caused the foil damage.

It's OEM part # ZNR 9k270
I'm looking for a replacement for it.

Info on it....
http://www.mouser.com/ds/2/315/ez016_erz_vd_dne-181976.pdf



On edit:
So far I've been hitting dead ends. I can guess the approx value for a replacement but would rather find the correct sub.
 

Last edited by PJmax; 05-10-17 at 10:45 PM.
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Old 05-11-17, 05:15 AM
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Thanks for the time and effort you have put into this, greatly appreciated. In the meantime I have been web surfing looking for options, I asked for 2 online quotes and got one back, $150 is the cheap option at the moment!

This is a 23 year old vehicle and was surprised to find the speedometer head is still available brand new for $250 including shipping from Toyota. At least it shows still available online.

James ,

Based on the information provided, we can repair your: 1993 Toyota pickup, not 4 runner, not SR5, pickup Cluster but need to see it for a firm estimate. Your estimated price range is $195 to $225 .

This quote is all-inclusive we never surprise you with extra fees. You get:

FREE UPS ground shipping both ways (within contiguous 48 states)
 
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Old 05-16-17, 01:35 PM
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I weighted my options here and could not bring myself to buy a used speedometer on line, if I could have sourced one locally I would have done it.

I opted to get mine repaired, the tech said that due to age that 2 of the capacitors had leaked and damaged the traces and some of the solder joints. The bill for the parts and labor was $150 with a 1 year guarantee.

He also mentioned that if speedometer is acting up it is best to have it repaired quickly before extensive damage is done.Name:  IMG_0001.jpg
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Old 05-16-17, 01:43 PM
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He did a nice job. Glad you got it worked out. Thanks for letting me know how it turned out.
 
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Old 05-16-17, 07:46 PM
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Thanks for the input always greatly appreciated.
 
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