Gossen MetraHit 23s rescued from leaked battery death

[mianchen]

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       

[trackman44]

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

[nanofrog]

Nice  rescue. 

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

[lowimpedance]

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.

[mianchen]

Nice  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 

[mianchen]

Good job, maybe change your 10 V pic  .

done

[retiredcaps]

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.