[GreenKeys] Model 33 progress (sort of)

Fri Jan 6 21:44:27 EST 2017

"So tomorrow or on the weekend I hope to finally test this thing with an
actual computer and see where my problem is."

Heh, you still haven't tried this, eh? You really are a glutton for
punishment.. cleaning away on the key contacts to cure a fault that might
just as well be in the TU. ;-)

As for the hot fault (gibberish) have you considered hooking up a scope to
view the PS output waveforms? Ultimately, this will tell you if your
problem is (or is not) in the filter caps. Start the unit up cold, and
while it's working well, view & measure ripple and DC output (avg.) on all
of the supplies.  Then let it run until it acts up.

Then once it begins to show the fault, re-do all of the checks and see
what, if anything, has changed. If you have a dying cap, you're definitely
going to see notably increased ripple and/or reduced DC voltage.

(This is mostly a mechanical system, so the typical / allowable ripple
might be a bit higher than you'd see in audio or digital gear, but if it
increases notably with temp - that's a problem).

On Fri, Jan 6, 2017 at 6:22 PM, Brad via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> Thanks Dave!  Will try that.
>
>
>
> A detail I forgot to mention but did to Wayne privately is that you don’t
> have to operate the machine at all for it to go nuts.  Simply plugging it
> in and leaving it on ‘Off’ for 30 min is enough to cause it to start going
> all gibberish immediately when you power on.  So I do think I must have
> some kind of cap problem there.  But that one key.. I mean maybe that could
> be the cap, maybe not.  Odd that only that and I think one other key have
> problems.  Anyway, I’ll try what you suggested and see what comes of it.
> Many thanks!
>
>
>
> *From:* David Tumey [mailto:davetumey at yahoo.com]
> *Sent:* Friday, January 6, 2017 3:20 PM
> *To:* Brad <unclefalter at yahoo.ca>
> *Subject:* Re: [GreenKeys] Model 33 progress (sort of)
>
>
>
> excellent.
>
>
>
> A can of spray coolant, or easier yet, a can of air (keyboard duster)
> turned upside down, can be used to troubleshoot your problem.
>
>
>
> When the machine starts acting up, you spray some suspect components with
> the coolant and see if it fixes itself.  If it does, the culprit may be the
> sprayed part.
>
>
>
> Also, you could benefit from an oscilliscope - take a look across the caps
> and monitor the ripple to see if it gets worse as the machine warms up.
>
>
>
> --dave
>
>
> ------------------------------
>
> *From:* Brad <unclefalter at yahoo.ca>
> *To:* 'David Tumey' <davetumey at yahoo.com>
> *Sent:* Friday, January 6, 2017 1:26 PM
> *Subject:* RE: [GreenKeys] Model 33 progress (sort of)
>
>
>
> Yes I gave it a real good clean.  It actually wasn’t that bad to begin
> with.  One of the few areas of this thing that wasn’t completely covered in
> grime.
>
>
>
> *From:* David Tumey [mailto:davetumey at yahoo.com <davetumey at yahoo.com>]
> *Sent:* Friday, January 6, 2017 5:46 AM
> *To:* Brad <unclefalter at yahoo.ca>
> *Subject:* Re: [GreenKeys] Model 33 progress (sort of)
>
>
>
> Brad,
>
>
>
> I am assuming you thoroughly cleaned that relay in the rear section of the
> UCC-6.  Lots of signals are routed through her contacts.
>
>
>
> --dave
>
>
> ------------------------------
>
> *From:* Brad via GreenKeys <greenkeys at mailman.qth.net>
> *To:* 'GREENKEYS BULLETIN BOARD' <greenkeys at mailman.qth.net>
> *Sent:* Friday, January 6, 2017 12:44 AM
> *Subject:* [GreenKeys] Model 33 progress (sort of)
>
>
>
> I guess I was kidding myself about having time during holidays, but
> tonight I finally did the 20ma wiring change on my 33.  I continue to be
> frustrated by an L coming up most of the time as an H.  I’ve really cleaned
> the key contacts as much as I think I can.  And the L is coming out more
> often than before, but still not there.  So tomorrow or on the weekend I
> hope to finally test this thing with an actual computer and see where my
> problem is.
>
>
>
> I’m also dogged by an issue where after about 30 minutes, the typing
> becomes jibberish.  I’m sure this must be a cap, but I’ve tested every cap
> even when it’s going wrong and unless I’m doing something wrong, they all
> come back ok. Ditto for resistors.   I’m thinking this must be one of the
> big caps given the time it takes for a problem to materialize.  I can’t see
> anything else that could overheat slowly like that or start putting out the
> wrong voltages.  I have the 1500uf cap Wayne was kind enough to give me
> which made a massive improvement in operation (prior to changing that, the
> machine buzzed loudly and mostly produced garbage when typing).  But it is
> second hand, so it’s possible maybe it has issues I’m not diagnosing.
> There are also two, I think, new old stock (or new) 250uf caps I got off
> ebay.  I’ve tried swapping them around but the problem still crops up
> around the same time.
>
>
>
> Anyway, looking forward to testing her out tomorrow, if I can figure out
> how to wire it up to my SWTPC.. which is my other question.. where are the
> wires for the connection to whatever you’re connecting to coming from?  I
> do have a two wire (black and red) pair coming from Connector 2…
>
>
>
>
>
>
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