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#1 Flottmann1 OFFLINE  

Flottmann1

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Posted Tue Sep 5, 2017 1:09 PM

I thought I'd look at a TI-99/4A Console, which only shows black Screen when switching on .
first I had changed the TMS9918A in this PAL Machine, nothing - Screen black

then I changed the SN76494N, and now - the original TI-99 Welcome screen

 

what is this Chip

Attached Files



#2 RickyDean OFFLINE  

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Posted Tue Sep 5, 2017 1:17 PM

I thought I'd look at a TI-99/4A Console, which only shows black Screen when switching on .
first I had changed the TMS9918A in this PAL Machine, nothing - Screen black

then I changed the SN76494N, and now - the original TI-99 Welcome screen

 

what is this Chip

Look here, this will get you started :) :   http://www.unige.ch/...i99/tms9919.htm



#3 Ksarul ONLINE  

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Posted Tue Sep 5, 2017 4:47 PM

It is the sound chip--and if it fails to initialize, you will get the black screen of death. . .



#4 schmitzi ONLINE  

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Posted Wed Sep 6, 2017 12:02 AM

I prefer the blue screen, © by Microsofft

 

:-D



#5 Flottmann1 OFFLINE  

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Posted Wed Sep 6, 2017 3:23 AM

I also found a TI-99 modified Console  by TI-Workshop Wiesbaden 32 K Memory

 

this show me

 

@1981  PEXAS INSTRUIEJTS

Attached Files


Edited by Flottmann1, Wed Sep 6, 2017 3:26 AM.


#6 Stuart OFFLINE  

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Posted Wed Sep 6, 2017 3:34 AM

I also found a TI-99 modified Console  by TI-Workshop Wiesbaden 32 K Memory

 

this show me

 

@1981  PEXAS INSTRUIEJTS

 

That shows that one or more of your video RAM chips are bad.



#7 Ksarul ONLINE  

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Posted Wed Sep 6, 2017 4:43 AM

Note also that the error is a bit intermittent, as the letter "E" is correct sometimes and bad at others. . .but it is definitely a VDP RAM issue, as Stuart noted.



#8 Flottmann1 OFFLINE  

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Posted Wed Sep 6, 2017 10:51 AM

I have also found a defect TI-99/4A Board with Ceramic TMS9900 ,thought these were only installed in the 99/4

Attached Files


Edited by Flottmann1, Wed Sep 6, 2017 10:53 AM.


#9 RickyDean OFFLINE  

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Posted Wed Sep 6, 2017 12:51 PM

I have also found a defect TI-99/4A Board with Ceramic TMS9900 ,thought these were only installed in the 99/4

If you don't want it, I'll gladly send you a plastic 9900, to take it's place, exchange.



#10 chue OFFLINE  

chue

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Posted Wed Sep 6, 2017 6:44 PM

I have also found a defect TI-99/4A Board with Ceramic TMS9900 ,thought these were only installed in the 99/4

 

Oh man, I have to open up my TIs now to check!  I'm not holding my breath though.


Edited by chue, Wed Sep 6, 2017 6:49 PM.


#11 Stuart OFFLINE  

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Posted Thu Sep 7, 2017 2:54 AM

If you don't want it, I'll gladly send you a plastic 9900, to take it's place, exchange.

 

Note though that it is soldered in, and would be a right pain to remove. White ceramic 9900's come up fairly cheap on eBay occasionally if you really want one. There are some rather fetching purple ceramic ones as well.



#12 RickyDean OFFLINE  

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Posted Thu Sep 7, 2017 5:27 AM

 

Note though that it is soldered in, and would be a right pain to remove. White ceramic 9900's come up fairly cheap on eBay occasionally if you really want one. There are some rather fetching purple ceramic ones as well.

I've got two, that I have had for over twenty years, I have desoldered them before  ;-) I thought about using this one on your 9900 board, All I have left to put on it at this time is the little stuff, that was not included in the package. All the IC's are mounted in sockets.






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