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Simpson 260 problems.

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sbs_2010

Sat Feb 11 2012, 05:18AM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

Just got a 260 series 3 off of eBay. (yeah, I know). The voltage ranges work good, the resistance ranges I had some trouble with, but after resoldering *most* not all, of the connections, I got it goin good. Now the problem is the current ranges. Any time I try to measure current, it pegs the meter, No matter what the current is. I connected it in series with a small red LED, and set on the 500mA range, it pegged it out. What's goin on? Something shorted somewhere?

Patrick

Sat Feb 11 2012, 05:42AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

sbs_2010 wrote ...

Just got a 260 series 3 off of eBay. (yeah, I know). The voltage ranges work good, the resistance ranges I had some trouble with, but after resoldering *most* not all, of the connections, I got it goin good. Now the problem is the current ranges. Any time I try to measure current, it pegs the meter, No matter what the current is. I connected it in series with a small red LED, and set on the 500mA range, it pegged it out. What's goin on? Something shorted somewhere?

thats a possibility, the other problem may be people (students) over currenting' the meter in its past life. Check to make sure you didnt short or change anything. then post back.

sbs_2010

Sat Feb 11 2012, 05:54AM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

[quote]
[quote]
thats a possibility, the other problem may be people (students) over currenting' the meter in its past life. Check to make sure you didnt short or change anything. then post back.
[/quote1328939250]
Well tomorrow I'm going to take the pcb out and go over all the solder connections and clean it all up really well and make sure nothing is out of place. Anything I should keep my eyes open for? I love the meter so far, I bought it for something to tinker on, and so far, it's been perfect for that. lol

Steve Conner

Sat Feb 11 2012, 07:46AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Sounds like the current shunt resistors could be blown.

Sulaiman

Sat Feb 11 2012, 07:59AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I agree with Steve, something in the current-shunt chain is open circuit,
most likely a resistor.
Using low voltage and a high resistance,
(e.g. 9Vdc, 1MOhm)
increase the current range until the meter reading drops
then you will know where the open circuit is.
(the resistor for the previous range) .

sbs_2010

Sat Feb 11 2012, 03:00PM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

Sulaiman wrote ...

I agree with Steve, something in the current-shunt chain is open circuit,
most likely a resistor.
Using low voltage and a high resistance,
(e.g. 9Vdc, 1MOhm)
increase the current range until the meter reading drops
then you will know where the open circuit is.
(the resistor for the previous range) .

But it affects all the current ranges, so would this method still apply? Anyone know which resistors I should be looking for?

Electroholic

Sat Feb 11 2012, 03:57PM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

Maybe this will help.

Patrick

Sat Feb 11 2012, 06:52PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

if there blown, then they're closed circuit--short, not open.

sbs_2010

Sun Feb 12 2012, 12:22AM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

Patrick wrote ...

if there blown, then they're closed circuit--short, not open.

Well, i did that test, sorta. 8v into 470k ohm resistor, connected into 50 microamp jack yielded about 17 microamps. Connect lead into the + jack,it still reads the same place, the needle never moves in any current range.

sbs_2010

Sun Feb 12 2012, 01:05AM

Registered Member #4392 Joined: Mon Feb 06 2012, 01:04AM
Location: Duffield, Va
Posts: 10

Well, took it apart and cleaned the backside of the pcb. Someone before me let a AA battery leak. Put it back together and now i lost Rx10,000. Gotta be a bad connection somewhere. Let my buddy use my soldering iron, so i'll have to wait till tomorrow then I'm going to reflow all the solder points. What's a good method to get battery gunk off of pcb's?

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