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repetto74

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Posts posted by repetto74

  1. Posted 

    The bodger in me wants to suggest reassembling it in the case with a bit of folded cardboard positioned just where you need to apply pressure ...  

    I do not really catch what do you mean here? You mean putting cardboard to simulate the finger pressure? How can I do that ?

  2. Posted

    Hi Dragonstomper,

     

    Yes the clock generator is socketed and was initially suspecting a bad socket so desoldered it properly and replaced with a precision socket before I made this video so no changes. Moving the PSU wires does not make any difference, I have checked voltages and they are all fine + applied fresh solder on the wires connection. Will try to clean the VDP socket with contact cleaner then.

  3. Posted

    Hi Dragonstomper,

     

    This video speaks more than words on the issue I have. Putting pressure with my fingers on top of the clock generator and on the opposite edge of the board (close to the GROMS and Sound generator) will make the TI99 to boot up normally. As I release gently the pressure I start having the video getting garbled and when I totally release pressure than it goes black. Putting pressure again will make the TI99 boot sequence to start again (beep sound) so I do not think this is just related to a bad video connection. There is a cracked joint or track somewhere in the area where the finger pressure is bending the PCB. At first glance I cannot see anything from the solder side of the PCB.

     

    <iframe width="560" height="315" src="https://www.youtube.com/embed/YMzSjsBfFKI"frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

     

  5. Posted

    Little update. I found that when pushing hardly on the left side of the PCB board and firing up the machine then it will boot properly on the welcome screen! If I leave my finger then it goes black again. I tried then to wiggle gently the PCB and can see distorsions on screen. Sometimes when I put some pressure on the right side of the PCB then the video come back again. Weird and probably related to a broken track or bad solder joint? How can I proceed to find it out?

  6. Posted

    Hi Guys,

    Reposting here as first request was posted on wrong section.

    ********************

     

    Today I had to open my TI99/4A because there were a lot of video glitches on screen (top half part of the screen with a pink overlay and sometimes a lot of video glitches popping out). It turned out to be the cart connector making bad contacts. After a good cleaning and a test on the fly all seemed to work again but after re-assembling the machine then the TI99/4A will not power up anymore :-(. All I have is a black screen(no sound). I am maybe suspecting the power switch contacts having gone bad. How can I test it and how can I clean the switch? Is there any reference for a suitable replacement?

    PS : The machine has the 32K mod hard wired in it and done by myself so could be also that a bad soldering somewhere is preventing a good start up.

     

    Thanks

    Rick

  8. Posted · Edited by repetto74

    Hi Guys,

     

    Today I had to open my TI99/4A because there were a lot of video glitches on screen (top half part of the screen with a pink overlay and sometimes a lot of video glitches popping out). It turned out to be the cart connector making bad contacts. After a good cleaning and a test on the fly all seemed to work again but after re-assembling the machine then the TI99/4A will not power up anymore :-(. All I have is a black screen. I am maybe suspecting the power switch contacts having gone bad. How can I test it and how can I clean the switch? Is there any reference for a suitable replacement?

    PS : The machine has the 32K mod hard wired in it and done by myself so could be also that a bad soldering somewhere is preventing a good start up.

     

    Thanks

    Rick

  14. Posted

    Hi,

     

    the PSU of my 800 XL is this one below

     

    3) CO61763-11

    Input: 220VAC 50Hz 26VA

    Output: 5VDC 1,5A

     

    Fuse: T 2.5A

     

    Thermal fuse: 125 degr.C

    T40/E

     

    Approval signs: VDE (German) GS (Geprüfte Sicherheit (="tested safety", German)

     

    Brand: FWGB which stands for Friwo Gerätebau GmbH. from Germany

     

    Notes: The FW1599 Typenr. is a factory Friwo number. Although it doesn't say it was made in Germany it was produced by a German company and the unit is over a very very good quality. Construction, lay-out are excellent. I haven't checked the schematics, but the set-up is pretty extensive for a "simple" 5V DC power supply.

     

    The big filter cap is of the Frako brand (www.frako.com), a very high quality German capacitor brand. FRAKO stands for FRAnkfurter KOndensatorenfabrik or "capacitor factory of Frankfurt". I couldn't see the brand of the smaller caps but I measured all of them with a high quality ESR meter and all show excellent values still.

    I think this supply is the most common one for the XLs around here and my preferred power supply.

    I am glad to hear it is a quality one compared to others. I have checked the PSU pcb recently and did not noted anything suspicious but was thinking to replace the tree elec caps as a precaution. I have a doubt concerning the two 100uF 25V caps as I am not sure if they are or not polarised. Both caps have a white band on one side so I assume this is to identify the negative lead? It is the first time I see caps with this odd marking.

    Thanks

    Rick

  15. Posted

    3) CO61763-11

    Input: 220VAC 50Hz 26VA

    Output: 5VDC 1,5A

     

    Fuse: T 2.5A

     

    Thermal fuse: 125 degr.C

    T40/E

     

    Approval signs: VDE (German) GS (Geprüfte Sicherheit (="tested safety", German)

     

    Brand: FWGB which stands for Friwo Gerätebau GmbH. from Germany

     

    Notes: The FW1599 Typenr. is a factory Friwo number. Although it doesn't say it was made in Germany it was produced by a German company and the unit is over a very very good quality. Construction, lay-out are excellent. I haven't checked the schematics, but the set-up is pretty extensive for a "simple" 5V DC power supply.

     

    The big filter cap is of the Frako brand (www.frako.com), a very high quality German capacitor brand. FRAKO stands for FRAnkfurter KOndensatorenfabrik or "capacitor factory of Frankfurt". I couldn't see the brand of the smaller caps but I measured all of them with a high quality ESR meter and all show excellent values still.

    I think this supply is the most common one for the XLs around here and my preferred power supply.

    Hi,

     

    I have a 800XL with this PSU and glad to hear it is a quality one compared to other. I have checked the PSU pcb recently and did not noted anything suspicious but was thinking to replace the tree elec caps as a precaution. I have a doubt concerning the two 100uF 25V caps as I am not sure if they are or not polarised. Both caps have a white band on one side so I assume this is to identify the negative lead? It is the first time I see caps with this odd marking.

     

    Thanks

    Rick

  16. Posted

    a drive formatted to itself will pass it needs a known good disk from elsewhere to be sure... please understand, Chances are it is perfect but... a bad alignment means it all works on that drive or all drives aligned to it the same alone. These are the cautions I used when explaining some of this. Perhaps I am being too much of a perfectionist. But disks make their way around the world and I like to be sure.
    If you can load protected electronics arts titles etc you are more than likely golden...
    -That's my 2 cents, for what it appears to worth.

     

     

    I will try to dig out some Atari disks somewhere and test the drive with them ;-).

  23. Posted

    Hi Guys,

     

    So I have tuned the drive speed to a nice 208,1 ms but all test are ok except the Head Step/Settle which still fails. Rails are lubed and head is cleaned with IPA. If I want to boot the formatted diskette to DOS it will just read and load fine with no problem at all. :?

     

    Considering this drive as working unless there is something more I can do to clear the failure. :woozy:

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