IBM Bigfoot rescue

[Wodan]

Heya,

My current project is saving a nice old IBM Bigfoot. The Model I have seems to have seen some wear and humidity and refuses to talk through a Soarer converter. Checking all the contacts I realized Vcc is shorted with one of the muxstrobe pins. This isn't supposed to happen ... I thought.

My first suspect was one of the two identical 14-pin DIP packages next to the connector. Desoldered both and one of them has a short circuit on between the Vcc pin and one other pin. The other identical chip doesn't have that.

Now I'm looking for a replacement IC. The IC name is OG 767368. The same IC is available from other manufacturers with the same numer 767368 With their own prefix replacing OG.

Does anyone in the EU have a broken/Harvested bigfoot with those chips? Looking for buy them.
They are available on aliexpress but take ages to arrive ...

Maybe someone else is having strange issues with their Bigfoot? If you connect a soarer and the first chip on the board feels warm, you might have the same problem. If I can't find a donor for such a chip I will order some on aliexpress. Will have leftovers then!

Les Chips:

[Nuum]

Don't you need Soarer's Controller instead of Converter for a Bigfoot?
I have a Bigfoot that I intend to use as donor, but I'm not sure if it works, looks pretty rusty as well.

[Wodan]

Oh yeah right it's the soarer controller of course. Very confusing those two.

My Bigfoot was really messe up but I sandblasted every part of it ...

[Nuum]

I'll have a look at the chips of mine for any obvious damage. If they look fine, I could send them to you.

[Wodan]

That would be awesome. Really curious if I can bring that thing back to life!

[Wodan]

Can any IBM vet explain to me what the layer of foam between the barrels and the plate is good for?

The one on my Bigfoot was so rotten, I completely blasted it off ...

Will this just make my Bigfoot louder or does that actually affect functionality?

[andrewjoy]

it keeps the barrels in place between the plates, it wont work without it .

I have been lucky , every model F i own ( and i have allot of them) has had foam that is serviceable.

Usually craft foam is used to replace it , you need something that will give so you can close the plates , but stiff enough to now let things move.

[tigpha]

Hi Wodan,

I believe that the foam is supposed to press the barrels onto the PCB, with sufficient pressure to maintain contact, and suppress rattling, but without the full force of the steel plate pressing down.

I am not sure if the sound changes a great deal. The neoprene foam seems to subdue the clicking just a little bit compared to the original foam. My Bigfoots have fortunately good foam, with no serious degradation. I replaced the foam as an experiment, and I am pleased with the result, but the change is minor compared to good original foam in my experience.

[Wodan]

Oh meh!

Well ... to the foam store!