Author Topic: Gossen MetraHit 23s rescued from leaked battery death  (Read 5288 times)

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Offline mianchenTopic starter

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Gossen MetraHit 23s rescued from leaked battery death
« on: November 13, 2013, 11:26:45 pm »
I got hold of a Gossen MetraHit 23s that was advertised as "working order", only to find it not working at all except DC mA, A stop watch and pulse gen.

Here are some pictures of its guts.















Other functions didn't work at all, here's what happened when measuring 10V DC



I took the whole thing apart, washed and scrapped off the horrible stuff, here is part of the repair board



Took me more than 4 hours from washing, drying to repair...and the hard work paid off:

Measuring 2.5V DC




10V DC



240V mains AC



DC Amp




I am happy :)   :-DMM  :-DMM  :-DMM
« Last Edit: November 14, 2013, 03:06:26 pm by mianchen »
 

Offline trackman44

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #1 on: November 14, 2013, 12:24:28 am »
Use an old toothbrush and isopropyl alcohol to clean it up and get rid of all that crud. Lets us know if it improves.

Will
How 'bout them Maple Leafs?
 

Offline nanofrog

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #2 on: November 14, 2013, 12:33:16 am »
Nice  :-DMM rescue.  :-+

What all did you have to do besides clean the leaked acid off of everything?
 

Offline lowimpedance

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #3 on: November 14, 2013, 12:35:15 am »
Good job, maybe change your 10 V pic  :).
Leaked battery gunk always gives me a scare when first discovered in a prized bit of gear.
Found a HP25 calc. in the bin yesterday, just took it apart and yes its toast  >:( damn nicads.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline mianchenTopic starter

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #4 on: November 14, 2013, 03:05:51 pm »
Nice  :-DMM rescue.  :-+

What all did you have to do besides clean the leaked acid off of everything?

I had to repair many traces that're eaten up by the leakage. The PCB is a 4 layer board, I had to use strong light from the opposite side to figure out the connections. It was painful especially when some of the vias were gone. I repaired 13 traces in total.

I also desoldered some of the big components (eg. pic 3)  to be able to reach and clean off the &£^$£ hidden underneath.

I was lucky, as soon as I finished, powered it on - everything was back to normal. I was worried that I might have missed something or connected something wrong - but I didn't  :-DMM
« Last Edit: November 14, 2013, 03:09:05 pm by mianchen »
 

Offline mianchenTopic starter

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #5 on: November 14, 2013, 03:07:02 pm »
Good job, maybe change your 10 V pic  :).

done
 

Offline retiredcaps

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Re: Gossen MetraHit 23s rescued from leaked battery death
« Reply #6 on: November 14, 2013, 07:42:08 pm »
It was painful especially when some of the vias were gone. I repaired 13 traces in total.
Great repair job.  The strong light is a good repair tip.
 


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