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repetto74

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Everything posted by repetto74

  1. Hi Jedimatt42 Thanks for your advice :-). Sorry If I ask but despite the fact I do have soldering skills I am really a noob concerning IC's architecture and how they work :-).
  2. Hi Jeddimatt42, So that means I can do the wirings according to the tutorial pinouts and consider I am wiring a CY7C199 i/O the Hynix SDRAM ?
  3. So a close look to the two datasheets will give some differences with the address lines which have different pinouts positions. I will have to pay attention to this when doing the wirings. Hynix SDRAM 32K Datasheet.pdf
  4. Hi Ksarul, Thanks for the datasheet :-) Good to have this one also
  5. Hi Jedimatt, Ok thanks a lot :-). Yes I think I may try using this SDRAM and see the result. Anyway the mod requires a lot of wiring so if not working it would be just a matter of removing the piggybacked SDRAM and replace it with a Cypress one. My soldering iron is heating.....
  6. Hi Guys, I am willing to perform the 32K internal mod as per the Tursi tutorial. I have a 32k SDRAM labelled HY62CT081ED70C and I was wondering if this one is pin compatible with the CY7C199 ? (they are both DIL 28 of course but the CY7C199 is shorter in width). Thanks Rick
  7. Hi Casey, This is exactly my feeling :-). The TI lower case just look as Upper Case and did make the mistake again as I was convinced having typed words correctly
  8. Hi Mizapf, No worries I do not consider your consideration as a bashing .I am glad to have the speech synth fully working. My knowledge of the TI99/4A is very poor and as I said the C64 has been my childhood companion 2 machines and 2 philosophy somehow different which makes a couple of things quiet confusing for a noob like me
  9. OK guys it has been sorted out thanks to Ciro from the Italian TI99 community Actually I was NOT writing words in CAPITAL letters so the TI99/4A does not understand this ....I know I am dumb All is working perfect now !
  10. Hi Guys, I have a speech synthesizer with me, great piece of hardware but either I do not understand how to make it work either there is an hardware problem. I tried to test its functionality with a TI Extended Basic module and keyed-in those lines 100 CALL SAY ("THIS IS A GOOD PROGRAM") 110 GOTO 100 The only speech sound I can get is a kind of continuous "OH OH". I have tried on two different TI99/4A and using different words to spell but always same result. Anyone can point me to any thing I may check? Thanks Rick
  11. Hi Arcadeshopper, Thanks for your advice. I have ordered a couple more of different brand SD modules and hope those will fix the problem. :-).
  12. Hi Guys, I have build up this nice device myself by seeking for components and outsourcing the PCB to Elecrow. The build up is pretty much straightforward and the ATMEL programming + fuse programming was done according to instructions. Now the only thing I can get from the device once inserted into the slot and the TI99 powered up is a 2x blinking of the led . The troubleshooting state a 2x led blinking is a bad or corrupted filesystem. I have tried 4 different SD card brand and sizes all in FAT32 format but still the same. Any of you had this problem using a particular SD card brand or has solved it in any way? Does anyone can confirm a working SD card brand? I have 3 areas where to look at : the 377 TLL is not an HCT but a LS instead (was not available at time of purchase) and should work but not tested by Ralph. The second is the Arduino SD Module I got from E-bay and it may be faulty. (it as a 3.3v and a 5v pin input and as far as I understood only the 5v input is used by the Flashrom99 PCB). Third one can just be all my SD cards not compatible even if this is really an unlucky situation. Thanks Rick
  13. So finally a fixed TI99/4A . Burned the TMS-2532A and installed it into the TI99 + pull-up resistor between pin 21 and 24 for the CS enabled. All is working good now !
  14. Hi Classic GMR Thanks :-). I have tested the ROMS coming from the working TI99 and swapped them to the faulty board and magic the TI99/4a will boot up ! :-) So it is just a matter of programming a 2532 eprom with the ROM code and I am good to go. Anyway I did find that the ROM position is the U611 and I do have the BIN file for it. :-)
  15. Hi, I have successfully managed to found what was wrong on a faulty TI99/4a. One of the two console ROM is bad and need to be replaced. I do have already a spare eprom to be programmed (2532) but can someone point me out to which ROM is the High Byte and which one is the Low Byte? The faulty rom is located left side from the two scratchpad rams and dame orientation. Thanks Rick
  16. I have desoldered the faulty rom and soldered a socket. Now anyone can tell me how to replace this chip with an Eprom? Which one and what file to program in ? The TI99/4A is a PAL version. I would like to do things simple and just replace the faulty ROM then I may consider later the PCB upgrades as explained . The ROM is the one sitting on the left of the two scratchpad Ram IC's and labelled : 8228 C71077 Many thanks for your help.:-)
  17. I would like also to replace one of the two ROMS because it is faulty and TI99/4A won't boot. So as far as I understood Thierry's page the original ROM must be kept into the console and a piggyback is required for the replacement? What about if the ROM is faulty? Is this going to work?
  18. Hi Guys, I have troubleshooted a faulty PAL TI99/4A and luckily I had another working machine to test by swapping the IC's. The faulty TI99/4A gives a black screen with a continuous pitch sound. It appeared that one of the two ROM chips is faulty, when swapping this rom into the working machine I have exactly the same problem. The ROM is the one sitting on the left of the two scratchpad Ram IC's and labelled : 8228 C71077 My question is to know the best action to replace this ROM. Is it affordable buying one or can it be replaced with any compatible Eprom ? I do have a programmer so in case this can be done I would like to have a guideline on how to proceed :-) Many thanks! Rick
  19. Hi Guys, So I had some extra time to continue the troubleshooting of this TI99/4A. What I did is to swap the suspect TIM9904 from the bad board to the board of the working TI99/4A. The good board will boot up to the prompt but now with the continuous beep sound. On the bad board the power up is giving the continuous sound with a black screen. So I need to consider the TIM9904 as bad but I do think it is not the only faulty chip.
  20. I am continuing my T/S report...alone I have taken voltages on the 8 VRAM chips and there is something suspicious. RAM 0 and RAM 7 have both less than 1V input while all the other are stable to 4V so I think there is something wrong here. I have checked also the Clock Generator TIM9904 and voltages of 5V and 12V are ok. Could this low voltages be a consequence of a bad ram?
  21. So I have checked voltage outputs at the mainboard and looks ok. I have 11.78, +5.2 and -5.1 so this is within range. Next move will be to desolder all VRAM chips and test them one by one.
  22. Hi, I have the exact same problem with a TI99/4A machine. Black screen on boot up and continuous beeping sound. I have swapped all socketed chips to a TI99/4A working board and those chips are good (GROM, VDP and Sound chip). I would like to test the PSU board now. I wanted to swap the PSU board with the one coming from the working TI99/4A but the two PSU board looks different, the one of the faulty machine looks like being the old model of the TI99/4 despite de fact it is mounted on a machine with the TI99/4A logo on it but I do assume that voltage outputs are the same. I cannot directly hook up the PSU of the good TI99/4A to the faulty one because the connector are not the same. On the suspect PSU board the connection is done via a molex connector to hook up the motherboard while on the other PSU the connector is soldered on the PSU board (on the other PSU I have wires soldered and connected to the Molex) Where do I need to measure voltages on the MB? I should check then for +5,-5 and 12 V right? So one lead of the multimeter on the GND pin and one on each pin to test the voltage? Sorry to ask I do have some basics in electronics but need a refresh. Thanks Rick
  23. So today I have tested all socketed chips by swapping them to my working TI99/4A. There are not many of them, the VDP, GROM and the sound chip. All are working good as my TI99/4A will boot up normally. I could also test the clock generator (socketed on my board) but on the dead machine this chip is soldered to the board but I do not think this chip is faulty considering that I do have a black screen boot with the continuous beep sound. What could be the next move? I am considering to invest in a desoldering station to easily take out all soldered chips. Maybe now removing the full bank of rams? I still have a doubt on the PSU board, do not know if a missing voltage can cause this problem and do not want to test it on my machine to avoid frying something if the PSU is at fault. Any idea where to measure for correct voltage outputs? The idea would be to hook the PSU of the working TI99/4A to the faulty board but the molex connector is different and need to find out an adapter for it.
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