total novice seeking to repair Porta-B

[muddywires]

I found an abandoned Hammond Porta-B in a warehouse and I am trying to get it playing.

It powers up and the tonewheel generators are screeching like hell, so I ordered some hammond oil on ebay.

When I play the keys there is a very very faint sound from the speaker (volume pedal all the way up). I'm wondering if that might be a symptom of the tonewheel generator being badly in need of oil, or if there's likely some other problem (bad tubes etc). additionally, if I hold down a single key for a few seconds, it sort of fades away and doesn't sound again unless I lay off it for a while

Does anyone have any suggestions for troubleshooting? Do these symptoms strike of any known common issues?

I have very little experience troubleshooting electronics so I'm hoping for some general guidelines of what to look for and how to go about diagnosing the issue.

Thanks!

[enor]

If the generator is screeching then it is turning much too slowly, so slowly that the generator notes are being filtered out by the band-pass filters on each pickup. That's why you have very faint sound. Regarding the sound that sort of fades out: it sounds like you might have percussion turned on. Don't run it any more until it's oiled and running silently! Then you can start trouble shooting; it's too early to say if you actually have a problem or not (apart from the generator sluggishness).

[Papus]

Replace the motor run cap IMMEDIATELY.
It is toxic and prone to exploding, sending carcinogenic material everywhere

[Tim Rinkerman]

http://www.captain-foldback.com/Hamm...orta_b_wir.zip Here's a link to Porta-B wiring diagrams. If you need parts, the Porta-B is basically an L-100. Clean all the tube sockets and pins, disconnect and clean all the multi pin connectors, if the tin can looking capacitor next to the run motor looks swollen, replace it before you do anything else..it is full of nasty stuff, and will squirt toxic junk everywhere if it blows up. It may take a very long time for Hammond oil to get to the bearings through the normal oiling routes...put some WD-40 in the oiing cups before you add Hammond oil to give the oil an easier path to get to the bearings.

[muddywires]

thanks for the tips everyone, will try these things and post an update

[David Anderson]

I have to push back against the WD-40 recommendation. WD-40 contains compounds that even the makers of WD-40 say are unsuitable for sintered bronze bearings over the long term. WD-40 is for keeping tools from getting rusty.

If necessary, use a combination of naphtha and oil. Naphtha is a clean solvent and will eventually evaporate, leaving only the oil behind. The only thing useful in WD-40 for this purpose is the kerosene.

[muddywires]

thanks david, I wound up just using the oil and the TWG is 80% better, there are 3 or 4 tone wheels that are still screetching so I'm gonna let it sit a little longer then try manually oiling the bearings on those individually.