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martin1b

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About martin1b

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  1. Ok. I'll get a Z80A on the way. Will check in once installed.
  2. BUSRQ (25) is at 5v. Yes, confirmed clock signal on pin 6. WAIT is not pulsing, but holding at 5v. Interesting, I always thought Z80 was only a CPU. So, would you agree the next step is a new Z80 CPU?
  3. @NIAD - Great info. It really helps. Thank you! Yes, ChildofCV is VERY helpful! @ChildOfCv I've confirmed continuity between U9 and the memory ICs. I also confirmed RESET goes low when the reset switch is pulled. MREQ and RD do NOT pulse on reset (at least I didn't see anything on the o-scope). MREQ (19) is at 1.25V and RD (21) is at 1.68. WAIT (24) is at 5V. Is that normal? I as able to get it hood up to a monitor, using composite out (FWIW). See below: VID_20210614_141227369.mp4
  4. Took every trick in the book but I finally got it replaced. Going through the RF output, I now get this (sorry for the rough video). At least I see characters on the screen. VID_20210610_125640411.mp4
  5. Trying to get the IC out and it's not easy. Doesn't budge. I would think the pins would move some. Are these glued down?
  6. Yes, 33, 34 are 5v and 12 is gnd. Ok, going to replace the VDP. Will let you know.
  7. Pin 36 has no signal. Pin 40 has a good clock signal.
  8. Q9 : one pin is 11.98, one pin is 5.59 v, other is 4.89. Resistance from E3 to the emitter of Q9 is 385 ohms. Looked all over and couldn't find Q6. Yes, I have an oscilloscope. Using it, I could not find a video signal on Q9 or E3.
  9. Good catch on NIAD's question. Yes, the picture doesn't change when pulling the right hand reset. I took the top board off and pushed on the socketed ICs on the lower board. After assembly, I noticed what appears to be a video reset when I power it on, using the composite monitor. You can see it and what happens when I use the reset button in the attached video. Does the ADAM have sound output other than from RF other than the DIN connector? When running RF, all I hear is a quick bit of static when turning it on (attached). VID_20210604_125626921.mp4 VID_20210604_130637422.mp4
  10. I'm feeding it into a vcr, then composite output into a video capture device. Here is the VCR with no input (to confirm we see video): Here is from the RF output of the ADAM through my setup: Here is from composite : I had a composite monitor laying around and confirmed I could see the VCR picture on it. When hooking up to the ADAM's composite out, this is what I get : I did notice a flicker when I turn it on. However, overall, it's the same. FWIW: I see scan lines when the ADAM is on. They disappear when it's off, so something is coming out : As I cycle the power, after about 6 or 7 times, they monitor goes dark on startup (not sure if that's my monitor. Likely not as it only happens when turning on the ADAM) Hope this explains what I'm seeing. Is there a special startup sequence, or buttons I need to push?
  11. When I turn the computer on, nothing changed on the screen (static) as if there is no video signal being sent. No BIOS screen, no sound or anything. I measured for video signal on the 'Monitor' output looking for video signal and there is none. I've hooked it up from 'TV' (RF output) through a VCR. Same issue. Then, from 'Monitor' (composite output) to composite in to my monitor. Also no signal. To confirm my video set up, I brought in another computer (TRS80 CC1 with RF out). I could only test RF output through the VCR and it worked fine. I would expect to see video signal on 'Monitor' but saw nothing. Notes: This had 2 data drives. To take it apart, I disconnected both of them and only installed one. It will still work, right? Other tests : I tried typing, nothing from the printer. I typed more, pressed 'Print', 'IV', 'V' (read that in the tech manual) and still no printing. I put a data pack in and I heard something very faint but but no actual tape movement. It must have moved some as there was a bit of tape out of the data pack when I removed it. On the printer startup, the carriage adjusts left, then the daisy wheel rotates for about 2 seconds. Assuming that's correct? I'm pretty new to the ADAM so don't know what you mean regarding 'Stand-Alone Memory Console with CV built-in'. The 2 green wires connecting to the print head look connected properly. Didn't see any socketed chips, but I'm only looking at the processor board.
  12. I recently bought my first ADAM. Turning it on, printer does it's start up, keyboard light comes on, but I get no video. I see no video signal out of the 'monitor' output. After doing some checking, on the processor, NMI (17) is low, but HALT, INT and WAIT are all high. To confirm, these are inverted, so NMI is active, correct? I have clock signal on pin 6. Looks like one of the places NMI connects to is U9 (TMS9928A) - video display processor. Thoughts on next steps?
  13. Thanks for the info! I have one on the way. Excited to get this system going. Now for some disks...
  14. Thanks for the reply. I'm not wanting to sell it. I love collecting vintage computers. I'm just wondering if it's worth the effort and cost to get it going and if there are a lot of them out there. I have 50 in the computer and the new ei to CPU cable will add to the cost. If the computer isn't worth 100, it doesn't make sense to do it. Glad to be part of the forum! Bill
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