Subject: PEB woes?

From: "Sullivan, BR" <[email-masked]>
Date: Mon, 26 Aug 2013 18:15:43 -0700

Help!  After testing all the voltage outputs of the PEB that seemed 
to eat RAVE 99 TI Speech adapter cards, and then putting it back 
together it failed with a very loud squeal and a green & black F18A logo 
screen.  I started the isolation process by removing one card at a 
time.  It turned out to be the least likely card, a Myarc RS-232 card 
that I removed from the SNUG-TI, which was working well before this 
recent move, and installed in this PEB yesterday.

Now that the squeal is gone and the F18A is showing an excellent 
rendering of the TI title screen it appears that the TI console is not 
talking to the PEB.  The ED/ASM module says there is no expansion 
memory, so I removed the SAMS card and put in a standard 32K card.  I 
still get the same results--no memory expansion, so I tried some "CALLS" 
from TI Basic to the Myarc 80 track FDC and get "Bad name", the same 
results for the HSGPL card.  So now I think it's the TI console or the 
Flex Cable Interface.  I have spare TI consoles in my closet, and at the 
CF7A+/NanoPEB station, so I try rhese first as of this morning I had not 
found the two spare interface cables I know are in the garage some 
where.  Once I proved the same test results for these other TI consoles 
I go to the garage, guess what box to start looking in first--good guess 
as I find both cables, but I still get all the same test results with 
all interface cables.

I'm at a loss as when I first started testing this TI-99/4A and PEB a 
week ago it was working well.  The only problem to begin with was a lack 
of speech, so I swapped out the RAVE 99 TI Speech adapter with another 
including a different TI Speech Synthesizer also, and it failed 
immediately.  I inspected both and found, in both cases, that a 15 ohm 1 
watt resistor was blown near the 7905 regulator which I guessed must 
also be fried.  Fortunately both TI Speech Synthesizers still work as 
sidecars.  Next the user defined "CALLS" in the 3MB HRD-16 card stopped 
working.  Later some other "CALLS" would also become flaky.  I thought I 
had found a pattern in one of the flaky "CALLS", but it turned out to 
not be the case.  Next an HSGPL CALL also becomes flaky, so I start 
thinking that the damaged RAVE99 cards may have also damaged the PEB 
power supply in some way.  That's when I completely disassembled the PEB 
and tested all the output voltages.  All to no avail.  So now I'm 
looking for new clear-headed ideas from anyone knowledgeable.

Bill R Sullivan (fdos)

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From: [email-masked]
Date: Tue, 27 Aug 2013 02:30:16 -0000

Bill...
I don't remember what all you have checked; but, what about your
household wiring at the wall sockets.  Are the voltages within specs? 
Are the wall sockets properly polarized?  Neutral is usually bonded to
earth-ground at the service entrance box—are neutral and ground at
the same potential at the wall socket(s)?  If you're using two different
wall sockets for console and PEB, are the two neutrals and the two
grounds at the same potential?  Stabs in the dark...
...lee

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From: Jeff White <[email-masked]>
Date: Mon, 26 Aug 2013 22:32:32 -0400

I think you might have a back plane problem close to the -12V line.  The speech card 7905 is a -5V regulator, fed by the unregulated -12V.  The RS232 also uses the -12V.

Jeff White

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From: Bill R Sullivan <[email-masked]>
Date: Mon, 26 Aug 2013 19:50:28 -0700

Hi Lee,

I have checked the AC, and it is very high, but that should not matter 
as both the TI console and PEB are connected to the same UPS.  Which is 
monitored by the Win98SE PC via USB.

Bill R Sullivan (fdos)

On 8/26/2013 7:30 PM, [email-masked] wrote:
>  Are the wall sockets properly polarized?  Neutral is usually bonded 
> to earth-ground at the service entrance box---are neutral and ground 
> at the same potential at the wall socket(s)?  If you're using two 
> different wall sockets for console and PEB, are the two neutrals and 
> the two grounds at the same potential?  Stabs in the dark...
>
> ...lee
>
>

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From: mark wills <[email-masked]>
Date: Tue, 27 Aug 2013 12:52:30 +0100 (BST)

Sounds like you've blown the buffers in the console. They are right next to the IO port.

>________________________________
> From: "Sullivan, BR" <[email-masked]>
>To: [email-masked]; [email-masked] 
>Sent: Tuesday, 27 August 2013, 2:15
>Subject: [TI994A] PEB woes?
>  
>
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>Yahoo! Groups Links
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From: Bill R Sullivan <[email-masked]>
Date: Tue, 27 Aug 2013 07:30:53 -0700

Hi Mark,

Not the case as I also switched out the TI console with two others and 
got the same results with both.  I believe Jeff got it right even though 
I can't find a 7905 -5VDC regulator on the Myarc RS-232 or a TI either.  
Maybe they use a simple voltage divider circuit on the unregulated -16 
volt line for -5VDC.  Anyway, I moved all these cards to The SNUG-TI PEB 
after removing the SNUG-TI cards, of course, and they seem to be working 
normally in this PEB, so I have to find cross on the -16 volt line some 
where on the bus or at one of the 8 bus connectors of the bad PEB or 
finish the adaptation of a mid-tower PC case I started doing several 
years ago for the SNUG-TI system.

How goes the TF project?  I also lost my TF cart in the move along with 
80 GramKracker and SuperCart, so I can't do any Forth development (TF or 
X4th99) until I can get both PEB systems back to fully functional.

Later dude.

Bill R Sullivan (fdos)

On 8/27/2013 4:52 AM, mark wills wrote:
>     *From:* "Sullivan, BR" <[email-masked]>
>     *To:* [email-masked]; [email-masked]
>     *Sent:* Tuesday, 27 August 2013, 2:15
>     *Subject:* [TI994A] PEB woes?
>
>     <mailto:[email-masked]>
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