Yet another one...

  • Greetings,


    Last Friday another Spanish unit appeared. With both overCLK 's and mine's this is the third known unit to appear. This one is like mine and different from overCLK 's. As both units were found in Catalonia while overCLK 's was found in another autonomous comunity the conclusion is that the units sold in the Catalan market were different from the ones of the rest of Spain (which have that stylish Triumph-Adler badge).



    As seen, the case is the standard one for the P2, but with the distributor badge (Guillamet) under the Alphatronic Sticker. My unit doesn't has the badge, apparently it was lost long ago but the glue is still there as a reminder of what once held.


    On the technical side, the computer is also a little different. Up to that point all known P2 units were 64K units (even mine, which is not a "U" model). This one is the unupgraded 48K unit.



    Now, the tests... the power supply is defective. It was shorting 5v, 12v and ground. All the boards were fine, there was no dead capacitor, even in the 48K DRAM card. With the boards in good shape I considered the computer to be ready for a test so I explained his owner how to wire an ATX into the backplane. After he checked the supply voltages from the backplane we considered it to be secure for the power up so he connected the three boards required for minimal operation: CPU, Keyboard and Video. The system resets correctly when powered on (also beeps as it should) and reacts to commands from keyboard. But the video display seems to be faulty.





    The monitor is known to be working fine, so the fault is up to the video interface. I think his problem is CSync but I would like to know what do you think the problem would be. VTAC? :grübel:


    Note: this unit is not mine and I haven't even seen it other than i pictures and a couple of videos, the images posted here were uploaded with the consent of his owner. I'll try to convince him to come here. When he rescued it he said there was some possibility he had the Spanish manuals but after a search he found none. Still, the simple fact to appear was enough to give me one of the best days of the year.


    Regards,

    Jaume

    When I tried to list all retro systems I have at home, the "The message is too long, must be under 500 characters" error appears! :lol:

  • Hello Jaume,

    thank you for your work to "experience" the alphaTronic P2 successfully.


    After the first look - I would think the VTAC 5027 or similar type was defective.

    With my P2U and I mean with gpospi and/or netmercer these error images had on the screen.


    The CRT-controller is from sks, but near TA controller.


    I had simply exchanged the 5027 and only had to adjust the horizontal and / or vertical controls a little on the screen. Then that's fine after that.


    Helmut

  • Yes I had a similar issue on my P3 (just some flickering horizontal bars on the screen instead of proper images). I replaced the CRT controller and everything was fine.

  • Hello Helmut,


    That's a relief. I told him the failure was most likely caused by the VTAC, but I wasn't completely sure. If that's the cause, the computer may be working very soon.


    I haven't only guided him to find what was preventing the computer to start, but I supplied him my remaining ATX adapter and 48K replacement kits.


    gpospi I was writing this when you replied. Thank you! ;)


    Regards,

    Jaume

    When I tried to list all retro systems I have at home, the "The message is too long, must be under 500 characters" error appears! :lol:

  • Greetings,


    It's been some time. Last week the VTACs arrived and the one in the card was replaced by one of the Polish units. The image was stable, cursor moved but there was no character at all! The invert signal was also activated, so the screen was green with the exception of the cursor... This means, that the data path from the DIN to the VRAM and from the VRAM to the shift register should be checked. Being completely blank with the invert I imagine:


    A) some 2114 may be faulty.

    B) some 74 series IC in the bus may be faulty.


    He has no scope to check the signals in the card... so he was stuck with it. For this reason, we agreed I would be in charge of the board for some time as I received one of such instruments not long ago. I don't expect it to be a long repair: as the VTAC retains most responsiblity for the generation of the signals, it shouldn't be as complex as a non-6545 PET.


    Regards,

    Jaume

    When I tried to list all retro systems I have at home, the "The message is too long, must be under 500 characters" error appears! :lol:

  • Hello jlopez and Shiri,


    is the CRT chip a VTAC 5027 or a really compatible chip?

    The first screenshots showed a few characters - but distorted.

    Perhaps Shiri or Jaume could see something on the screen (with the new CHIP) as it appears after switching power on the P2?


    Jaume:

    Is Shiri very far from you?

    After your report from you, I will hopefully look through the misconduct with the sks screen controller at the weekend. But is the TA controller a bit modified (I mean the BAS signal level ..?)

    is from sks, but near TA controller


    Greetings @ helwie44

  • Hello helwie44,


    After the replacement, image seems stable, at least from what I've seen. It is a perfect blank, but inverted screen.


    Picture courtesy of Shiri


    The replacement is a legit VTAC, otherwise we wouldn't see the cursor (or anything at all). This seems a fault from the video RAM, latches or maybe some other common component coming before the shift register because (as seen on SKS documents and later with the EPROM backups) MSB is the invert signal. As you said, the TA board is a modified SKS but this remains unchanged.


    Yes, Shiri is a bit far, but even if he was near I couldn't meet him due to restrictions on mobility... Still, he sent me the board through mail. When it arrives, I'll give it priority over the PETs.


    Kind regards,

    Jaume

    When I tried to list all retro systems I have at home, the "The message is too long, must be under 500 characters" error appears! :lol: