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Offline cookee_nz  
#1 Posted : 27 March 2015 06:53:56(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,948
Location: Paremata, Wellington
Hi all,

Those of you with any 6041 switchboard units will want to take notice of this.

About 20 years ago, I embarked on a project to convert one of our club smaller factory original layouts to Digital. One of the things I thought would be interesting was a track-diagram control panel and a 6041 Switchboard was ordered as part of the project materials.

I duly made a diagram board, wired it all up and the rest is history. It worked very well and was great for the public to play with. After a few years with one thing and another I took quite a break from active involvement in that layout and somewhere along the way the control board became disused and/or faulty. Various wires had been disconnected and it was in a bit of a sorry state.

I recently decided to resolve this and set about getting it working again. Except it would not work - totally dead, zilch, zip, nada!! What the????

I had noticed something a little odd, there was some corrosion around the two connectors for the supplementary power for the status LED's. I didn't really think too much of it, until I had to dig deeper.

Opened up the cover of the 6041 and immediately recognised something I've not seen since the 80's.

Inside the 6041 (and possibly the 6040 also) is a smallish Varta Battery which had leaked quite badly all over the PCB (see photo's below). This is what was causing the corrosion around the connectors. The damage is pretty dramatic and I can only encourage anyone using a 6041 to check them immediately. If you see corrosion it needs urgent attention.

If there is not corrosion evident, I suggest that sooner or later the battery will leak - this type of battery are notorious for this problem.

I last saw it in the 80's when I was repairing German made Triumph-Adler electronic typewriters. They used a near-identical Varta battery, (a little smaller) and many logic boards were severely damaged before the factory finally got wise and started mounting them on a separate PCB. In fact the problem was so bad that we removed the batteries as a matter of course and ran wires from the battery to the PCB before they developed a fault - and before the factory modified the design.

Repair of this one is probably possible, identifying the damaged components will be the biggest challenge and running jumpers for any damaged tracks.

I'd be interested to hear if anyone finds the same problem.

Note, to remove the battery really needs a solder-sucker, but if you have a good steady hand, you can gently lever the battery off the PCB while holding your fine-tip soldering iron against each of the 4 pins. Start at one end and raise the battery progressively - ie a little on each pin at a time.

Edited by user 27 March 2015 12:16:36(UTC)  | Reason: Not specified

cookee_nz attached the following image(s):
6041-6.jpg
6041-2.jpg
6041-3.jpg
6041-4.jpg
6041-5.jpg
6041-7.jpg
6041-8.jpg
Cookee
Wellington
NZ image
thanks 5 users liked this useful post by cookee_nz
Offline Shamu  
#2 Posted : 27 March 2015 08:39:21(UTC)
Shamu

Australia   
Joined: 12/07/2011(UTC)
Posts: 1,068
Location: In a building site in Yeppoon
Bit of a bummer Cookee,

I hope for your sake its only a 2 layer board and not a sandwich board...... kiss it goodbye then.

I lost track of how many PC motherboards I had to trash due to "battery cancer" before they realised plug-in battery packs and finally button cells were the norm by the mid 90's.

I used to use a thin baking soda paste to clean them up before any remedial work on the salvageable ones.

Does make me a tad concerned if there are any batteries in my CS2 or MS2's, can't see why but you never know.

All the best with getting it going again.
Sad when its cheaper to buy a new 29640 starter set from Germany than a CS2 on its own in Oz, welcome to the joys of Marklin down under .
thanks 2 users liked this useful post by Shamu
Offline Chook  
#3 Posted : 27 March 2015 13:59:04(UTC)
Chook

Australia   
Joined: 15/08/2012(UTC)
Posts: 234
Location: Perth, Western Australia.
Cookee, Shamu is right on the money with the baking soda.
I have repaired a couple of these types of faults and usually begin by removing any mechanical connections (like the DIP switches) and binning them.
The next step is to neutralize the acid - I use not paste but a wash and a toothbrush - in fact I immerse it. The problem is its the gas exuded from these batteries which does most of the damage. The next step is to use Meths or alcohol, again in a bath with a toothbrush. the problem now is that some of the electrolytics may also be damaged underneath which is what you can't see.
Next step is several baths in distilled water and a final dry with a hair dryer.
Next is to coat the whole lot in automotive clear coat after it is perfectly dry.
The clear coat is great as it seals everything and also allows you to solder/desolder after without causing too much mess. And it prevents the same thing ever happening again and locks any corrosion at that point in time. ie you may still have corrosion but it wont get any worse.

I rebuilt a Sharp M1 video camera which had fallen into salt water many years ago using this method. It was time consuming and tedious but I got it working reliably again and learned a whole lot about colour television in the process.

Regards....Chook.
thanks 4 users liked this useful post by Chook
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