Jump to content

repetto74

Members
  • Posts

    282
  • Joined

  • Last visited

Everything posted by repetto74

  1. https://forums.arcade-museum.com/threads/lets-design-some-pokey-replacements.515774/page-10
  2. Ok moment of truth... It was indeed the Pokey chip unfortunately. Swapping it with my own unique good spare has just fixed the problem 🙄. Bad luck and it is very difficult to source this chip at a decent price (especially the version that works with the Atari 8bit line of computers). Are there any open source projects for an FPGA Pokey in progress recently?
  3. Noted I will put it aside then :-). Hope to see one day an open source FPGA replacement for it. Actually the replacement Pokeys are quiet pricey!
  4. Hi, I have the exact same issue on my 600XL. Cursor on top left but no ready message. Cartridge works. Did you solve it finally? If yes, which IC was the bad one? 🙂 Rick
  5. HI, I was playing on my Atari 800XL and suddenly the video turned to garbage. Since then there is no normal boot to the prompt. I just get a weird brown screen and a humming sound. I checked the power supply voltage at the pin connector with no load and oooh damn I read 15v!! 😑 I checked the 800xl with another PSU I have and miracle the machine booted again! This post is just to tell users to not freak out if the original PSU fails. In my case it was the internal BD303 transistor who failed and was probably outputting less more that the 5v required under load. Better anyway to stay away from those old PSU and prefer a din-usb cable to be used with a standard usb phone charger 😄 It was close!! IMG_5871.MOV
  6. Thanks I'll pick from there and start the troubleshooting. There is although a change. I tried to hook the console to the composite output and now I do see an image but very very distorted which let me think that at least CPU, VDC and RAM should be fine. I think something is wrong on the video circuitry and maybe the TMS-RGB board is fried which may explain the total absence of an RGB signal. IMG_5170.MOV
  7. Hi, Some progress 😇 I have hooked the Colecovision to the composite mod just to test if that was making any difference and indeed I do have a very scrambled picture in a loop with a black screen. With the RGB mod I just get nothing as I said, no video sync. Could this be a dodgy videochip? I am measuring only +4.6v on the board pcb so wonderign if the insufficient voltage can cause this. IMG_5170.MOV
  8. When you say a "blank screen" do you mean black screen or white noise (snow), as the former would generally suggest the video output stage is operational (creating a video singal) but the unit is not producing any video graphics, while the latter would generally suggest that the video output stage (i.e. RF modulator) is not working and so there is no video singal being produced. It is a blank screen not black screen, meaning that my TV is reporting a "no signal" so there is absolutely no video generation from the circuitry (either the clock is missing or either the VDC is fried). I will start to troubleshoot and check all ICs voltages (I want to bypass the power switch for that first as on the Coleco it is a well known issue that power switch just fail with time and do not provide correct levels of voltages required by some ICs). Next will be to check the clock and reset from the CPU. Is there a place where I can find a good schematic for the Coleco?
  9. Hello, Drama 😨. I was having some graphical glitches recently on my Coleco and decided to desolder and give a good service to the infamous power switch. After cleaning and mounting the switch back, glitches where still there. I started to wobble the switch and noticed indeed weird graphic things happening on screen leading to the conclusion that he switch is very flaky and may need to be just replaced. Unfortunately I suddenly noticed a weird graphic pattern on screen and all turned to black. Since then, the console will not boot anymore. The video signal is not hooked up by the TV, just nothing (referred as a blank screen). I checked voltages at the power Supply connector and we have steady +12v and +5v. I randomly checked voltages on the video ram and notices +4.6v which seems to be a little bit low (+12v and -5v looks ok) I though that the power supply did fail completely but there are voltages when switched on. Where can I start to look at? I do have a logic probe and an oscilloscope even if I am not a super expert on hardware troubleshooting but any advice would be appreciated. I do have also some spare 4116 and 2114 rams in case but wondering how much they could be the cause in a total absence of video signal. Hope I did not fry the VDC or the crystal? I would like to make a test and bypass the power switch. But before hooking any wires at the back of the switch vias I want to be sure that I will not short anything. The switch has 6 pins, left side is the +12v and right side +5v. Where I should bridge to power the board? If I refer to the schematic below I should bridge top pin with the center one on both +12v and +5v rails. Just as extra information, this Coleco has 2 video mods, one is the composite mod and the second is the TMS-RGB mod (both working good). I was hooked up on the RGB connector when troubles started and did not had a chance to try to connect to the composite circuitry (the pcb was on the test bench and not connected to the RCA jacks mounted on the Coleco case). I am willing to try to hook it up with composite although I do not think this will make any change.
  10. Hello, Drama 😨. I was having some graphical glitches recently on my Coleco and decided to desolder and give a good service to the infamous power switch. After cleaning and mounting the switch back, glitches where still there. I started to whobble the switch and noticed indeed weird graphic things happening on screen leading to the conclusion that he switch is very flacky and may need to be just replaced. Unfortunately I suddenly noticed a weird graphic pattern on screen and all turned to black. Since then, the console will not boot anymore. The video signal is not hooked up by the TV, just nothing (referred as a blank screen). I checked voltages at the power Supply connector and we have steady +12v and +5v. I randomly checked voltages on the video ram and notices +4.6v which seems to be a little bit low (+12v and -5v looks ok) I though that the power supply did fail completely but there are voltages when switched on. Where can I start to look at? I do have a logic probe and an oscilloscope even if I am not a super expert on hardware troubleshooting but any advice would be appreciated. I do have also some spare 4116 and 2114 rams in case but wondering how much they could be the cause in a total absence of video signal. Hope I did not fry the VDC or the crystal? I would like to make a test and bypass the power switch. But before hooking any wires at the back of the switch vias I want to be sure that I will not short anything. The switch has 6 pins, left side is the +12v and right side +5v. Where I should bridge to power the board? If I refer to the schematic below I should bridge top pin with the center one on both +12v and +5v rails. Just as extra information, this Coleco has 2 video mods, one is the composite mod and the second is the TMS-RGB mod (both working good). I was hooked up on the RGB connector when troubles started and did not had a chance to try to connect to teh composite circuitry (the pcb was on the test bench and not connected to the RCA jacks mounted on the Coleco case). I am willing to try to hook it up with composite although I do not think this will make any change.
  11. Hi, I made the same mod with the TMS-RGB board and the Mini Din 8pin. I have a nice and crisp picture but sound is very low and I can barely hear it. I connected both L/R audio cables to the pin 5 of the DIN connector. I have a PAL machine by the way. I am missing something to get louder audio output? Rick
  12. Hi, I know this thread is old but I’ll try my luck. I have mounted a Uno Cart but today with cip shortage, the stm32f407vet6 can be sourced more easily and at a better price. This should be a straightforward alternative of the stm32f407gte6 (only difference is flash size of 512k i/o 1mb) I programmed the vet6 with a good checksum but all I get when I plug the cart on my 800xl is a red screen. Is there a specific setting when programming the firmware on the vet6? Any specific block where to write the firmware? Many thanks.
  13. MIC5504 is available on Aliexpress at a low price.
  14. I would like also to build the UnoCart2600 and use the VET6 alternative microcontroller. If I understood correctly the firmware originally developed for the VGT6 is 100% compatible? Do we need to recompile or amend it before flashing it?
  15. Hi zx-81, Indeed that was it!! Changed to a 1k pull-up and now the cartridge is working perfectly :-D. Thank you for your support and nice piece of hardware this one ? ! Sorry for the late reply I had many things to sort out in the past months so not so much spare time to dedicate to the 8bit retro computing :-). Cheers, Rick
  16. Hi, Can someone advise the correct value to use for the resistor? I want to use a 10k resistor by default but maybe if someone can confirm that this value is correct.
  17. The Coleco will usually crash when trying to load a game stored into the first eprom. I'll get a garbled screen like this one enclosed or a freeze on the cart menu. Pressing the reset will either load the same game stored into a certain position on the eprom (DK something) or show up the message to insert a cart into the module.
  18. I have tried to program another 27c801 in position 1 but same issue. I have checked the CE signal on pin 22 and I do have 4.5V when not selected then dropping to 0V when a game from that eprom is selected.
  19. If I swap the two eproms then the Coleco will load the game available on the first memory bank of the second eprom. As the menu is on the first eprom then i can only load this unique game but indeed it loads. It is maybe irrelevant but worth to mention. The 74LS688DW I have installed is marked 74LS688 and the package was not the good one (smaller then the pad positions on the pcb) but I managed to solder it properly without any shorts. Question is are pinouts different from one package to another?
  20. Hi 5-11, I have built this cart based on the gerber and schematics available for it. There are no bypass capacitors. I have made some extra testings after finally replacing the loose socket with a good one. Basically all games stored in the second eprom are working fine when selected from the menu (the pcb is making use of two M27C801 of 1024k each). If I select a game stored on the first eprom then the Coleco will either crash or load the prompt screen asking to insert a cart and reset will just do nothing. I have checked the first eprom with the programmer and it verified good with the original bin. Here is the schematic of this project.
  21. Hi Guys, I have built this multicart and used the two bin files to program the two eproms. I can get to the menu but the loading is very erratic. Sometimes the game loaded is not the one selected from menu and other times it crashes. I have I think an issue with a socket where the eprom is not fitting tight but is loose. Can someone let me know what is the value of the pull-up resistor? I put a 10K but not sure this is the correct value to use. Thanks and great project for our beloved Coleco :-)!!
  22. Hi CrossBow. Thanks for your inputs. I have a bunch of RGB scart cables here for other machines so I may try my luck with one of those or buy the dedicated RGB cable. My SMS is the PAL-G version for Europe by the way.
  23. Hi, I have tried with a composite cable I made a few months ago for the Dragon32 and it worked. Same pinout but I am not really satisfied with the result. Can the SMS be modded for the RGB output or is it native?
  24. Hi, I need a composite video cable for a SMS I recently pick-up as it came with aerial RF cable only. Is the pinout of this cable the same as the one for the C64/Vic20 composite DIN cable?
  25. That did the trick! Soldering a jumper wire has solved. I can connect now to the wifi and set-up the Plus Store account. I cannot really explain why there is a broken line here, I have checked the continuity and it looked fine. Bad PCB? Anyway it works that's the most important :-D. Thank you for your support, this cart is ra really nice piece of hardware :-). Let's put it in a cartridge shell now!
×
×
  • Create New...