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Hand held exhaust analyser

Hand held exhaust analyser

(OP)
Hello everyone,
another headache,my portable 4 gas analyser has stopped working. The SMPSU that plugs into mains is supplying the 10vdc to the pcb,as I have checked the power lead,and I've checked the DC socket solder points on the board. But where do I check next? (The picture is large so it can be downloaded and view with Windows Viewer)

RE: Hand held exhaust analyser

Can you contact the OEM for a repair manual?

Without a schematic, trouble-shooting can be very difficult. But it's perhaps worth examining the PCB under a microscope, especially around any components that are hot or mechanically strained, for cracked solder joints. But the odds are quite low you'll find anything that obvious.


RE: Hand held exhaust analyser

HAHAH. I was about to suggest you clean your very dirty board before I noticed the dust didn't move as I scrolled across the picture.


Unfortunately your supply check and perhaps some other voltage checks on the board are about the most a neophyte can do on these types of failures.

There is one more easy thing to check. Cast about the board a little trying to look up the data sheets on a few different integrated circuits you find there. Looking at the data sheet find their supply pins, be they plus or minus supplies and measure them carefully without shorting to nearby pins to see if they are what they should be. +5V, +7V, +10V, +12V, -5V, -10V, -12V, etc. This will show if an on-board regulator has taken a walk or not. If one has they are usually fairly easy to fix.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Hand held exhaust analyser

I would start with the surface mount electrolytic capacitor (I think it is) that's just below and to the right of the O2 sensor plug in the picture. It looks a bit bulgy, but that could be lighting...


Other than that, with a schematic or a repair manual, it would be TOUGH.

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx

RE: Hand held exhaust analyser

(OP)
Wow...thanks for the replies fellas (thinking you are all men)

Quote (itsmoked)

HAHAH. I was about to suggest you clean your very dirty board
The cheek of it bigsmile not that dusty,it must be your screen bluegreedy
I'll try your other tips later,need to get to work.

Quote (IRstuff)

I would start with the surface mount electrolytic capacitor (I think it is) that's just below and to the right of the O2 sensor plug in the picture
That has 470uf 35v on it. Just done some googling on how to test it with a DMM,using an EM129 on 20M ohm setting,it reads 5.56.
The analyser is an SPX which got bought out by Bosch. Quite possibly Bosch won't have anything to do with it,little chance for any repair manuals/schematics
Thanks again

RE: Hand held exhaust analyser

re: fellas -- I think women here will tolerate "guys"

Caps are generally cheap, under a couple of bucks. I can only say that my ludicrously expensive to repair fridge was brought down by a cap that cost $2.35 at Fry's; it was going to cost $400 to send the board to someone in Kansas to replace that cap.

TTFN
FAQ731-376: Eng-Tips.com Forum Policies
[IMG http://tinyurl.com/7ofakss]
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers


Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx

RE: Hand held exhaust analyser

The caps are definitely the go to shotgun repair attempt. You would take careful notes while carefully removing each one. Then find exact replacements or ones that match datasheet to datasheet.
Those SMD aluminum caps can be a real pain in the butt to solder in or out.

Often, the pin voltage tests I described above would show anomalies if caps were a problem.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Hand held exhaust analyser

How old is the device?

RE: Hand held exhaust analyser

(OP)
The analyser is ten years old,give or take. Bosch acquired SPX in 2012,quite possibly Bosch won't have much about the product. There are several other brands,that are quite similar,such as Kane Auto 4-1 and Probike Microgas. Possibly they were made at the same factory,but branded according to the company

RE: Hand held exhaust analyser

Age ten years is old enough to follow the capacitor related advice given above.

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