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Delta

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  1. Sorry, I just saw your message now. My notifications seem to have stopped. I am still awaiting the arrival of my logic probe...although I do try all 3 motherboards every so often hoping by some miracle they will start working again!
  2. Thank you! It may arrive faster than the one I ordered last week! I even had to send him a follow up email asking when he intended to post it...I have 3 poorly Ti's desperate for a logic probe (I have given up on my oscilloscope as that has been sent from China despite the seller saying he is UK based 😂)
  3. You are quite correct about that!
  4. Thank you. I have replaced ordered a logic probe which should be here soon. Hopefully it is not being sent from China.
  5. I suppose I will have to wait...in the meantime, I could desolder the processor and get a socket in there...after all, what could possibly go wrong?!
  6. Is there no way to check the CPU without an oscilloscope?
  7. Yes, it is old electronics, but this fragile? Adrian (of Adrian's Digital Basement) is always replacing ICs on the Ti's he works on and doesn't seem to have this problem 😊 The power supply and capacitors were the first thing I checked and they seem to be fine. Maybe I did kill the VDP...but without another to test, how can I be sure?
  8. I have ordered an oscilloscope... What can I check on the processor with just a multimeter to determine if it is (sort of) working?
  9. I need a few more straws, however short! I don't have any more VDPs to test with and despite what happened with you is it really just a coincidence that the problem occurred after I desoldered the ROM and/or soldered the socket? I would say that both boards which exhibit the no display and continous beep show correct voltages on the video RAM and processor. However, they both show 0V on the bottom right pin of the ROM - it was 3.3V when it was working. However, the top left pin shows 5V.
  10. Just done it...no difference. Probably did a better job this time too!
  11. I'm afraid it's just the light or the angle. I have checked for both shorts to the tracks on either side and for continuity along the track. I have noticed pictures often make the solder points look much worse than they actually are.
  12. When you say "I acquired an f-18a popped it in", do you mean the VDP? That being the fourth VDP you tested which did work?
  13. The ROM is definitely in the correct way and I have checked the pads. It does appear to be ok. However, short of desoldering the socket and putting the ROM back in, I am not sure what else I can do. Have a look at the pictures and see if you can spot anything.
  14. There has been a development, but not a good one 😒 I managed to acquire another Ti which was working...I wanted to test the other ICs...however, this Ti only had a socketed VDP so I was initially only able to test the other 2 VDPs...at least that was a start. I then realized I would have to desolder one of the ROMs to introduce a socket...so I very carefully desoldered the ROM to the right of the processor and soldered the socket. I then inserted the ROM to do a quick check before testing the other ROMs. I switched the new Ti on and to my horror...no display and only the infernal high pitched sound! I have managed to break my newly acquired working Ti! I feverishly checked my soldering to ensure there were no shorts or dry joints... Nothing. I now have 3 non working boards with 2 showing the same symptoms.
  15. I managed to put the original strip back on...and all the voltages at the system board connection are now correct but the video RAM has the +5V missing. So both of my boards are in a better albeit non working state. The first seems to have all the correct voltages but that dreaded continous beep and no display. The second has no beep, no display and the video RAM voltage is not correct. I am using the same VDP, Clock IC and ROMs in both.
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