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Geneve 9938 issue


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#1 BeeryMiller OFFLINE  

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Posted Tue Jan 22, 2019 8:37 AM

I noticed this issue last spring, and this past weekend, switched things around to confirm.

 

I am not seeing red on my Geneve.  Has anyone ever observed a specific color missing to know the likely cause?  I pulled up John Strain's schematic from the 9938 to the video port, but have not started testing anything with an ohm meter to see if there is a break in connection yet as I have to find my ohm meter.

 

Any thoughts on a likely failure?  I do not know if the video lines run on a layer below the surface, or if they are visible.

 

Any thoughts appreciated.

 

Beery



#2 mizapf OFFLINE  

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Posted Tue Jan 22, 2019 9:55 AM

Cable OK? Solder joints on the board OK? I had that issue now and then until I made a completely new cable.



#3 BeeryMiller OFFLINE  

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Posted Tue Jan 22, 2019 10:02 AM

Two completely different cables.  I will be testing solder joints once I find my meter.

 

Beery



#4 InsaneMultitasker OFFLINE  

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Posted Tue Jan 22, 2019 10:20 AM

Is the video jumper near the neck of the card set to the right position?



#5 BeeryMiller OFFLINE  

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Posted Tue Jan 22, 2019 10:51 AM

Is the video jumper near the neck of the card set to the right position?

 

I will have to investigate.  I looked for a video jumper the other day when I was swapping/testing eproms for Mike, but did not see a jumper.  Guess I need to take another look.

 

Beery



#6 Schmitzi OFFLINE  

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Posted Tue Jan 22, 2019 1:46 PM

Hi, here are some infos I´ve gathered together over the time,

for the jumper settings have a look at page 3.

 

Attached File  GENEVE-9640-&-TI-99-4A-&-MONITORS-PINOUT-v16c.pdf   5.96MB   8 downloads



#7 BeeryMiller OFFLINE  

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Posted Tue Jan 22, 2019 1:53 PM

Thanks for the information.  I guess I will have to squint a bit more to confirm the pin selection.  As this Geneve was given to me something like almost 5 years ago, I assumed it had been properly configured since it was an RGB monitor that was being used.  In hindsight, that may have been an error on my part and the previous owner may have had it improperly configured for all these years.

 

I will know the answer in about 4 hours.....

 

Beery



#8 InsaneMultitasker OFFLINE  

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Posted Tue Jan 22, 2019 3:27 PM

 

I will have to investigate.  I looked for a video jumper the other day when I was swapping/testing eproms for Mike, but did not see a jumper.  Guess I need to take another look.

 

Beery

It's close to the 8 pin DIN and easy to miss.  Hopefully that's all it takes to resolve.



#9 BeeryMiller OFFLINE  

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Posted Tue Jan 22, 2019 6:06 PM

Thanks everyone for the comments.  Turned out, it was just a dip switch set to composite instead of RGB.  

 

Beery



#10 RickyDean OFFLINE  

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Posted Tue Mar 19, 2019 10:15 AM

Does anyone know of a reliable source to purchase a couple of 9938 video chips. I bought one from china a few months ago, and believe that I documneted a failure here on atariage concerning it. But that chip I believe caused a new ram chip to go bad and even after replacing the ram chip the 9938 is showing artifacing all over the screen. But when I put a known good 9938 onto the board the artifacting is gone. All the ones I see on ebay are from china, so does anyone know of a source here in the states? Thanks


Edited by RickyDean, Tue Mar 19, 2019 10:16 AM.


#11 atrax27407 ONLINE  

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Posted Tue Mar 19, 2019 10:31 AM

Maybe Jim Fetzner will chime in here. He can tell you what to look for in a genuine chip online.



#12 RickyDean OFFLINE  

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Posted Mon May 13, 2019 7:27 AM

Well, I bit the bullet and purchased two more 9938's from China, 1 came in Friday, waiting for the other.

But that being said, the one that came in Friday is not operational, and I expect that the one coming in behind it will be no different.

They were both purchased from the same seller on ebay, but not the seller that the prior bad 9938 was purchased from a few months ago.

If this next one does not work, I will attempt to modify a 9958.



#13 helocast OFFLINE  

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Posted Mon May 13, 2019 3:31 PM

Well, I bit the bullet and purchased two more 9938's from China, 1 came in Friday, waiting for the other.

But that being said, the one that came in Friday is not operational, and I expect that the one coming in behind it will be no different.

They were both purchased from the same seller on ebay, but not the seller that the prior bad 9938 was purchased from a few months ago.

If this next one does not work, I will attempt to modify a 9958.

Slightly OT, but did you pay (or is anyone else) pay premiums (tariff increase or actual customs fees) on China orders lately? Jameco, Digikey, and a few others charge up front, but so far Ebay hasn't tagged me though I try to keep restock orders on my parts bins under $100 actual value.

Just curious.

 

Doug



#14 RickyDean OFFLINE  

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Posted Tue May 14, 2019 5:51 AM

Slightly OT, but did you pay (or is anyone else) pay premiums (tariff increase or actual customs fees) on China orders lately? Jameco, Digikey, and a few others charge up front, but so far Ebay hasn't tagged me though I try to keep restock orders on my parts bins under $100 actual value.

Just curious.

 

Doug

Sorry for the delay, helocast. No so far I have just made offers or paid the price listed on Ebay. I too, have paid some surcharge to Jameco, but not Mouser as of yet. Haven't done any business with Digikey recently. My question is why does a chinese seller, sell a product that will not work from the moment it is installed, where is the financial gain from that when I am just going to ask for my money back. I have waited patiently for this to arrive, just to discover from the get-go, it is worthless.






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