Overhead Compass/Temp Fix

Which repair guy is that?

 

SOLD

 

SOLD

 

You could repair it your self, I did mine.

It's easy, buy a solder gun, take apart the unit, solder on new resistors.

I have extra resistors.....

 

I did this fix and it went out again a few years later. Are you saying that if I soldered on New Resistors it should resolve the problem?
If so, I’d be happy to take a couple of those resistors off your hands.

 

This is what I did, recently - through advice from TacomaWorld.... and so far so good!

I actually bought the incorrect Resistors twice, and had various degrees of lumination.

Send me a PM w contact info



My inboard, longer leg is too far inboard... keep yours over the green board area only. You have some room vertically to be away from the green board, more than mine is.

Original below

 

So when I took mine apart, the 510 was missing completely. I ordered a new one on Amazon for like a dollar fifty, when they showed up, it was a strip of fifty of them, they are about half the size as the OEM one's, soldered one on a year ago and it still works perfect. So, if anyone needs one I'll send u one for free, or you can send me your board and I'll solder one on for you for a 10 dollar fee, thanks and good luck

 

510 is the resistance. 51 x 10^0 ohms. X^0 = 1, so 51 ohms.
There is another very important part of the equation that isn't printed on the body of the resistor, which is the size code.
Its really hard to gauge the size from a picture, but based on it them being a similar length to the width of the SOT223-4 packaged chip (edit: That is a BCP54 1A NPN power transistor) near them on the board, I'd gauge those resistors to be probably 2512's.


The rest of this post is a general message about doing this repair:

https://www.arrow.com/en/categories...ance+Value:51;Package/Case:2512;In+Stock:Yes;

Now I've noticed a number of people showing that they've replaced the resistors with AXIAL packaged resistors. That isn't necessarily a problem in and of itself, HOWEVER, it is important to note that the physical size of the package is related to the part's POWER RATING. The surface mounted 2512's have power ratings of mostly 1W, but occasionally more (as high as 3 watts), whereas those axial resistors being used as substitutes are only rated to 1/4 watt.

Does that mean that the circuit actually *requires* 1W+? Not necessarily. Sometimes you pick an oversized component because it is more convenient to use. There is a massive difference between soldering a 2512 and soldering an 0605. So if you're a HOBBYIST, you'd probably favor the physically larger 2512 where possible. HOWEVER, circuit boards that are installed in cars are NOT assembled by hand. They are assembled by ROBOT, and the robot doesn't care if its an 0605 or a 2512. That means that the question of what size they will choose is going to come down to the COST. The least expensive 510-2512 at the above link is over $0.25 per volume of 1. But if you drop the package size down to 1206 to get 1/4 watt rating like those axial resistors, the price drops to just $0.06. That is a difference of $0.19, which doesn't seem like a terrible difference if you're buying 1 or 2 resistors, but if you're buying 10 for every vehicle and a million vehicles per year, that adds up pretty fast. Now granted, they're not buying them individually, they're buying them by the millions at a much lower price per unit, but you still end up with the proportional difference multiplied by 10 million units. Little things like that add up to a lot, which tells me that they didn't decide on 2512 just for the fun of it. That circuit actually *NEEDS* a bigger power buffer than is afforded by a 1/4 watt resistor.

Now those resistors also happen to be run in PARALLEL.
That means that the overall resistance is going to be 1/R = 1/51 + 1/51, R=25.5 ohms.

So why then didn't they use a SINGLE resistor that is approximately equal to the overall resistance?
The answer again, is POWER.
Because now you drive that power rating up to a total of 2 watts.

With the two 1/4 watt axials in parallel, total power is 1/2 watt.
With the two 1 watt SM's in parallel, total power is 2 watts.

Now as people with the 1/4 watt axial resistors have noticed... it works. Yep, sure does. But here is the thing; those resistors are almost certainly running more power through them than they are rated to withstand. They don't suddenly go into STOP mode if the power goes too high, they keep working, but outside of their designed specifications. The consequence of this? The resistors will run hotter than they should, and could potentially fail. And a failure of a resistor? If your luck is good, they fail DISCONNECTED (infinite ohms). If your luck is bad, they fail to 0 ohms, potentially destroying whatever is being powered through them.

EDIT: That is a BCP54 1A NPN power transistor. Basically, its a low side switch. Normally, you would use a component like this at roughly HALF its rating, so about 500 mA. If that is a 5 volt circuit, 500 mA means potentially as high as 2.5 watts, however there is another set of resistors (the 181's) taking the output from that transistor. If its a 12 volt circuit, 500 mA means as much as 6 watts. They definitely chose those resistors big to handle big power.

My advice would be to NOT use 1/4 watt axial resistors, or any resistor rated at under 1 watt.
In fact, I would DEFINITELY stick to surface mount resistors. Huge surface mount components like those ones are actually a lot easier to work with than trying to stick axial components onto SM pads. You just need to pick the right tools and perform the proper preparations.

1) Clean off all old solder using solder wick:

Vastar Solder Wick, 3 Packs Desoldering Wick, Solder Braid 2.5mm Width, 1.5m (5ft) Length

https://www.amazon.com/Vastar-Solder-Packs-Desoldering-Length-x/dp/B073TRWY19 (or similar).
2) Clean the board with alcohol or acetone. Paper towel works well for this.
3) generously apply rosin flux to the pads:

$14 MG Chemicals - 8341-10ML 8341 No Clean Flux Paste, 10 milliliters Pneumatic Dispenser (Complete with Plunger & Dispensing Tip)

https://www.amazon.com/MG-Chemicals-milliliters-Pneumatic-Dispensing/dp/B00425FUW2 (or similar. Note: DO NOT use ACID CORE / PLUMBING solder unless you want a fireworks display)
4) Heat up your soldering iron, clean the tip using brass tip cleaner or a damp sponge:

Pointed Tweezers, Stainless Steel Long Tweezers for Electronics, Anti-static ESD Tweezer Kit Non-magnetic ESD Tweezers Jewelry-making, Laboratory Work, Hobbies, Y & R Direct Electronic Tweezers

https://www.amazon.com/Electronics-Anti-static-Non-magnetic-Jewelry-making-Laboratory/dp/B07BKRL3QV
5) apply a blob of solder to the iron tip:

KESTER SOLDER 32117 24-6040-0027 60/40 Stand, 0.031" Diameter, 44", 1.5" (Pack of 2)

https://www.amazon.com/KESTER-SOLDER-32117-24-6040-0027-Diameter/dp/B01MSWYSUU
note: most people prefer leaded solder, not the ROHS lead free mamby pamby stuff which is a lot harder to work with and doesn't stick as reliably. Possibly one of the reasons these resistors pop off for people is BECAUSE of the lead free solder they use.
6) Grip the component with tweezers: https://www.amazon.com/Electronics-Anti-static-Non-magnetic-Jewelry-making-Laboratory/dp/B07BKRL3QV
7) Rest your left wrist and pinky finger on the table, keep fingers of left hand all touching together, maneuver the component centered over the pad and HOLD IT THERE.
8) Touch the soldering iron tip to the joint between the component and the pad on the board, hold it there until you see the solder flow evenly over the joint, then retract tip, KEEP HOLDING TWEEZERS IN PLACE FOR A MOMENT UNTIL SOLDER SOLIDIFIES, then remove tweezers.
9) Repeat solder blob and solder the opposite side of the component. It is NOT necessary to use the tweezers on the second side, since the first side is already in place.

Optional: You can use alcohol or acetone to clean up the mess of flux from the board, if you care to make it "pretty" again. Its not necessary though.

Surface mount soldering is not difficult if you have the proper tools and learn a few basic techniques. Things like cleaning the pads before you try soldering to them, and using copious amounts of flux. These 2512 resistors are so huge that a moose could do it. I regularly solder surface mount components that have multiple legs that are as small as a quarter of a millimeter wide with pin center-to-center spacing of 0.5 mm. These things need to be aligned to within well UNDER a quarter of a millimeter. And I do this withOUT the benefit of "surgeon's hands" -- I have unsteady moose hands.

 

Wow

 

I could use a couple..

 

Now that’s a thorough reply!

 

PM me ur address and I'll send u a couple

 

Now that's Tacoma World worthy! Also the first time anyone explained that the correct 51 ohm resistors are actually 1 watt each and why, instead of only 1/4 watt - and the 1/4 watt ones are being used by a guy charging $59.95! Used the link provided by 96carboard to order four of the 1 watt 51 ohm resistors. Guess what? The right ones cost $1.04 total delivered in two days...

 

Like I mentioned earlier in this post, PM me ur address and I'll send you the proper 510 res. For free

 

Can't beat free, address inbound!

 

PMed

 

Hold your horses there a moment. You mentioned that the ones you received were "about half the size". That would make them probably 1206's, which are likely 1/4 watt. Not the 1 watt resistors that the original's would be.

 

There actually 511s, they are bigger than half, and wer ordered as a direct replacement/fix, mine has been in over a year with no issues, don't know what the math is, only that they work, u need any ?

 

No, I certainly don't need any (if you saw my components shelf and electronics workstation, your jaw would hit the floor). I'm also concerned that you switched 510's for 511's. Instead of 51 ohms, they would be 510 ohms. Why it works.... ? I guess there may be some flexibility in the circuit it drives. Are you *sure* they're 511's?

Now one thing about using a higher resistance... less current means less power, so if they are 511's, then you're likely not running them over their spec. So what is the side-effect of this change? If the segmented LED display is actually powered through those, then maybe its not as bright as it would be with 51 ohm resistors?

In any case, glad that they're working for you, but I don't suggest that anyone would go out of their way to use those resistors as substitutes for the proper 510-2512's.

 

Thx for your wealth andknowledge, I do not claim to know any of that stuff, but it's nice to learn something new