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dphirschler

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Posts posted by dphirschler

  1. Posted

    Concerning the RF Modulator mod... I just discovered the connector easily come apart if you slide the rubber cover off. I desoldered the original connections and soldered in an A/V cable (Red and White=audio, Yellow=video). It looks profesh after I put it all together!

     

     

    Darryl

  2. Posted

    Joysticks that don't work right

     

    I had a joystick that would not go up. And it was not the Alpha-lock key. I described my problem here in this thread (http://atariage.com/forums/topic/230818-joystick-horror-story-with-a-happy-ending/).

     

    The solution is to clean the contacts on the flexible circuit board inside the joystick. I used 90% isoprohyl alcohol. Take care not to "clean" the silver pads painted inside the TI joystick. If you do, it will just rub away like a scratch-off lottery ticket. But even that can be saved by either painting it again with conductive paint, or applying a small square of conductive tape.

     

    Darryl

    • Like 1

  3. Posted · Edited by dphirschler

    Bad (currupt/garbled) video

     

    When I first dug my TI's out of the basement and blew the dust off them, I powered up my beautiful beige console and the screen looked garbled, like this.

    post-39934-0-72915400-1415493591_thumb.jpg

     

    I asked the folks here and they quickly identified bad VDP RAM as the culprit (http://atariage.com/forums/topic/228756-diagnose-this-sick-ti/?p=3053085).

     

    1) Modify my console by installing an F18A board. The F18A is a snap-in replacement to the 9918A video processor which gives VGA output from the TI. This board uses its own VDP RAM (baypassing the bad VDP RAM on the motherboard). The TMS 9918A chip is socketed, so it literally is a snap-in mod. The more difficult part of the mod is cutting a hole in your console casing to make a spot for the VGA connector. There are some photos of other people's case mods for the VGA connector here http://atariage.com/forums/topic/228626-who-has-vga-out-on-their-console/.

     

    2) Identify and replace the defective VDP RAM chip(s). It seems the easiest way to identify the bad one is to stack a good one on top of the supposed bad one, making sure all pins make good contact, and look for the video to improve. The technique was mentioned in the first thread above (diagnose-this-sick-ti). There was one other thread which described how to possibly identify a bad VDP chip out of circuit (http://atariage.com/forums/topic/229064-testing-4116-ram-chips-out-of-circuit/).

     

    I went with solution 1, and am happy about it. The TI never looked better than on this VGA screen.

     

    Darryl

    • Like 1

  6. Posted · Edited by dphirschler

    No sound from the console

     

    One day my otherwise good console stopped producing sound. Two possible solutions were presented to me here on this forum (http://atariage.com/forums/topic/231542-no-sound-from-ti-console/).

     

    1) Replace the sound chip, which might have gone bad. This solution fixed my issue. I just happened to have another TI motherboard which was bad. It powered on with an angry sound and glitchy video. The angry sound was enough to tell me that at least the sound chip worked. I swapped it out and my silent TI was again producing sound. It was an easy fix as the sound chip is in a socket. What I should have done before swapping the sound chip was to test speech. I am not certain, but I believe speech would have worked even with a bad sound chip. Am I correct? It would be an additional useful diagnostic step. PM me if you know the answer and I will correct this post.

     

    2) Re-solder the back A/V connector which might have come loose through years of plugging/unplugging. One user reported that this was the problem and simply re-soldering the connection fixed it.

     

    The sound chip is highlighted in blue in the following picture. The audio/video is shown in the upper left corner.

    post-39934-0-53013500-1415468197_thumb.png

     

    Darryl

    • Like 2

  16. Posted

    I have a black console that suddenly stopped outputting sound. Any recommendations how to proceed with repairs. OLD_CS1, this is your old console that you had done some work on trying to get s-video working. Not saying your work caused this, but maybe you'll have some special insight.

     

    Darryl

  24. Posted

    OK. I had to sit on this for a while. I was confused by what looked like conflicting responses. What I think I understand is that the chip WILL work for me, just not with the 512K image. Seems this chip has a maximum capacity of 64K. Is that correct?

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