Overhead Compass/Temp Fix

A little off topic, I got tired of re-soldering everytime it got over 100 degrees and the glare making the display unreadable, so on my new vehicle I decided to forgo the temp display for a guagepod and aftermarket temp guage (auto dims) works much better for me.




guages are from http://www.digital-auto-gauges.com/products/Auto-Thermometer-Gauge-for-Trucks-and-Cars.html

guage pods: http://www.gaugepods.com/toyota.html

 

So I ordered the previously mentioned 510s from DigiKey, but it was the wrong part. This is the next one I'm going to try if anyone was interested in getting some. Would be nice if someone that knows about these could confirm this is the correct part we should be using to fully replace these resistors. I accidentally broke mine in half when removing it originally, didn't realize they were so fragile!!
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P510XCT-ND

UPDATE!! Even though it was too small, i figured i would try since i paid for them. This worked. Although i need some advice.. When testing it, the whole area got hot as shit. I'm sure they do since it already has an issue with de-soldering. But anyone that knows anything about these resistors, does the picture below look as if it will be ok? does it matter how small these are? I thought about putting 2 next to each other on the same circuit but wasn't sure if it would work right.





TLDR - Will this catch my truck on fire?

Edit: I tried this 2nd variation. With 2 of the 511's. This ALSO works. Will this help take some of the load on these tiny ones? Which variation should i use. I bought 4 of these little ones total.

 

The physical size of a resistor is its ability to absorb and handle the heat. That resistor is way too small. Resistors are used based on their resistance in ohms and their heat wattage. The "ohms" can be correct but the wattage can be too small. Going larger in wattage is OK electrical wise, it generally just becomes a "space" issue.

The "511" resistor you have on there now is 10 times too much resistance as well. A 511 marked SMD resistor is a 510 ohm resistor. The 510 marked one is a 51 ohm resistor. Check out this link for an SMD size calculator.

http://www.hobby-hour.com/electronics/smdcalc.php

 

Do you think if i lined up all 4 of the ones i have, like in the 2nd picture i added, that it would be ok? sorry for the retarded question.

 

No, in the second picture you have now halved the resistance to around 255 ohms total, still too much. You might get away with doing all 4 like this as the wire ends will offer some heat handling capability.

 

The "510" resistor is a 51 ohm resistor (first two digits are the number, last is the power of ten, so 51 x10^0 = 51 ohm).

A "511" resistor is a 510 ohm resistor. Four in parallel will be the equivalent to a 128 ohm resistor, which is still about twice what you need.

As someone else pointed out, it is also smaller, which means it is less able to dissipate heat (probably rated at half or 1/4 the wattage of the larger resistors).

Regarding the digikey part 06RadiantRed linked to, please measure the size of the original chip, length and width at least (thickness if you can measure it). The part you linked to is 0.252" long by 0.126" wide. Does it match?

 

Thanks for the reply JKD and 45longcolt,

I called up digikey when I noticed they were smaller than I expected. I should have done more research instead of blindly order off a link posted here but I didn't. O well. Anyways, when I called up, he suggested I try the one I linked a few posts ago. I do not have any calipers easily available so its hard to get an exact measurement. But comparing the two sizes:
511: 0.126" L x 0.063" W
510: 0.252" L x 0.126" W

The 510 is twice the size in both L and W.

When lying the 511 on a stock 510 from our PCB this matches up almost perfectly. So I'm fairly certain the one I linked, that I have on order should fit.

Is there any way I can link these to work like I want? The 511 from the pictures is a 1/3w and the bigger 510 i have on order is a 1w.

 

0606RadiantRed,

As JKD said, there are a couple minor issues with your choice of surface mount resistors.

They are a bit too small physically, and heat dissipation (wattage handling) is going to be a problem.

In a properly working display, the two 510 (51 ohm) resistors offer 25.5 ohms of resistance in parallel.

In your first pic, you have 47 ohms total, and the second pic (with three resistors) you have 43 ohms. You are going to have more heat generated, and a dimmer display due to the use of small 510 ohm components.

My suggesting is ditch the surface mount components. Go to Radio Shack and get a couple 1/4 watt 51 or 47 ohm axial resistors.

Read my guide here for repairing your Tacoma compass.

There is no reason for a DIY'er to use surface mount components. I repair these professionally as a side business; I use SMT resistors but I heatsink them. Axial lead resistors from Radio shack will give you a similar heat dissipation advantage.

 

mine just went out

 

mine is out.....lunchtime then fix-it time.

I love TW!!!!

 

omg no. please dont.
1. you need to use a little bit of flux next time..
2. use the correct resistor only. those solid state jobbies are pretty dang accurate and for a reason.
3. you wont catch your truck on fire.. but that may ground and short out.. making the rest of the circuit unusable.
4. holy jesus holy jesus that is one ugly solder job! (no offence man)


it may work for a short time, but that is definitely not good.

 

fixed. it works again....i had it off for a long time.....just gonna always leave it on now.
it was clear the weak solder OEM jobby.

my solder jobby....a little COBBY as my Soldering kit was a tad HUGE for the micro-solder job that it was.
I'm happy with it.

 

secretsquirrel, Thanks for your great write up, just pulled mine down and the 510 was hanging down like it was on a hinge, soldered both and now im back in business, thanks to everyone for their input

 

Thanks for the replies. I will definitely just wait for the right resistor to come in. And Transplant, I know I'm not any professional solder guy, but I thought I did a pretty good job! I dont know if you have done this yet to yours but those resistors are small as shit. And the tiny ones i got are only 0.126x0.063 inches. Here is one shot with my thumb in the pic, I couldn't really solder it any more cleanly than that with my regular soldering iron

 

yeah you right, my bad. im an electronics tech...ish. i forget sometimes not everyone is well versed. i mean.. the job of solder is to make an electrical connection.. doesnt matter how it looks as long as it does that! so bravo for even attempting, and more so for getting it to work!

 

FYI, Even if your resistors dont look like the solder has broken, resoldering them will fix it. At least it did for me anyway. I took mine apart today cause mine didn't work, but the solder joints didnt look bad. I resoldered them myself anyway. And now it works! Thanks TW!

 

Awesome fix. All of 30 minutes.

Thx

 

Thanks for the write up! Great fix, saved some major $ and it's on for the first time in 3 years!

 

I soldered all the 510s and no luck. The display has a burn mark in the top left corner. Anyone know where I can order a new board?

How much does a board cost from the dealer?

 

See my sig.