GRALAB 450 - Repair

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titrisol
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GRALAB 450 - Repair

Post by titrisol » Wed Dec 02, 2020 7:48 pm

I bought one from eBay, and the seller sent me another one that said "not working" with a note saying that no one had bid on it and it was mine to tinker.

Well, the not working timer did work, as long as the start/reset bar was pushed.
Since I had nothing to lose, I asked my neighbor (retired electronic engineer) what could be wrong and he told me to open it and look at the board
Peeling the rubber feet gave me access to 4 screws in the back, and then had to do a bit of coaxing to remove the front dials and this showed up:

Image
Gralab 450 Board - built as a tank


His recommendation was to look in this order
1 Start/Reset switch (corrosion due to humid environment)
2 Capacitors (useful life)
3 Ribbon cable (broken)
4 Voltage regulator (broken)
I ruled out 3 and 4 because the timer-panel was doing what it was supposed to

I started on (1); which seemed the more logical one. I guessed it needed a good contact cleaner treatment (spray, actuate, spray, actuate) . Tested and that seemed to do the trick.
Just in case I also cleaned all the other contacts, and measured the capacitors (2) which seem ok for now but expect to replace them in 3-5 years as they naturally lose the electrolyte liquid inside of them.

So now I have 2 working timers.
Last edited by titrisol on Wed Dec 09, 2020 8:44 am, edited 3 times in total.
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alexvaras
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Re: GRALAB 450 - Repair

Post by alexvaras » Wed Dec 02, 2020 11:37 pm

Good job! Congrats!:)

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Philip
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Re: GRALAB 450 - Repair

Post by Philip » Thu Dec 03, 2020 8:27 am

Well done!
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Re: GRALAB 450 - Repair

Post by Julio1fer » Thu Dec 03, 2020 8:43 pm

Good work! Electrolytic capacitors will last a lot longer if they are kept polarised, i.e. under voltage. Be sure to turn the timers on every now and then.

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Re: GRALAB 450 - Repair

Post by Brazile » Fri Dec 04, 2020 7:03 am

Oh, that's a great story. Congratulations!

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