oldrx

Circuit board repair - possible? *pic*

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Below is the circuit board from my Podi oil pressure gauge. I managed to fry it as you can see and the manufacturer wont reply to my many requests for quote on a new board. I assume its a goner but not knowing anything about tiny black rectangles that somehow know things thought I would check if anyone can enlighten me?

I think it was my fault trying to run it off a double relay that feeds the fuel pump also, too many on/off cycles in quick succession when i was trying to fill float bowl and turn off before it overfilled (too much fuel pump).

image1.JPG

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Got any docs?

Circuit diagram, pics of undamaged unit, etc?

Happy to help, it looks pretty saveable, assuming the rest of the bits ain't pooched.

Give it a clean w/ isopropyl alcohol or somesuch, a gentle buff, see if you can read the part numbers.

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Thanks man, I will clean and report back. I dont have any data on it but will have a hunt on the net and maybe try the manufacturer on the off chance. If I put a pic of a fried board on their facebook page it might elicit a helpful response!

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Got it cleaned up a bit, so its labelled Q1 on the board but the part marking on the component is melted off. However Q2 below that is the same size im guessing is probably the same component - it has printed on it 2306A. Could be one of these? which according to that website is this from element14  - datasheet

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Could well be. It's connecting to the oil sender or the guage?

What is U2? (markings).

Flicking the relays on and off might have caused a voltage spike (like points), trashing the devices, but it should have been designed to cope with that.


I can't see the PCB traces, so not sure how it's wired. That section of the board could either be a regulated DC power supply, at lower than 12V or perhaps a constant current supply, depending on the rest of the system. Normally I'd expect to see a BJT in that kind of role, not a mosfet, so tricky to tell without more info about what it's doing and how it's connected.

 

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Yeah im not sure its been designed that awesome. Its a small company with no aftermarket support.

It is connecting to the gauge side pretty certain.

U2 has a symbol like a rugby ball with two parallel lines angled through it, then 7550-1, then i think maybe a #

 

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http://www.e-ele.net/DataSheet/HT75XX-1.pdf

Just a simple 5V power reg, capable of 100mA out.

Still need more docs or better pics to work out the function of the other but bit of the board, to guess if the blown transistor is the same as Q2 (there's zillions of different things in that SOT-23 outline).

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I took another photo using my kids magnifying glass lol may be of some help not sure. Damn this drag and drop funtion on OS is awesome!

image1 (1).JPG

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I think your best bet would be to replace Q1 with the similar part (solder sucker, and a temp controlled iron at ~700F, 60/40 solder not plumbers 70/30) and then hook up the battery (not the rest of the system) and test the output volts (should be 5V?).

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Oh yeah, are @kempy or @Ned anywhere near you? They're bother clever chappies who know electrickery, I'm more of a digital hack, I just know some basics.

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@h4ndWash your mouth out young man!, I'm a tinkerer!

@oldrx  I have a temp controlled soldering Iron but nothing specifically for SMD's , Ive been avoiding that world

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If you just want to send it to a man who will likely be able to figure out whats going on and will likely fix it (but will charge you) send it to Peter at ProTechNZ 09 818 5115 and tell him Ned sent you. His workshop man Ali can fix just about everything, the mans a magician!

if you're near auckland and want me to replace a couple parts for you (have decent irons and a little bit of skill) then im happy to do that for you too and just hope for the best :)

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1 hour ago, Ned said:

If you just want to send it to a man who will likely be able to figure out whats going on and will likely fix it (but will charge you) send it to Peter at ProTechNZ 09 818 5115 and tell him Ned sent you. His workshop man Ali can fix just about everything, the mans a magician!

if you're near auckland and want me to replace a couple parts for you (have decent irons and a little bit of skill) then im happy to do that for you too and just hope for the best :)

Yeah!? Ok I wont turn that down thanks man. PM incoming...

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