Recent content by mrthreeplates

Still looking... thanks!

updated the label so I don't forget years later!

Well, since adding the additional capacitor, my model 1 has booted reliably. No more failures after many attempts. I can only assume it was caused by c43. So, I'm calling it fixed for now and buttoning it up. Thanks for the help and suggestions! On to the next project!

Hi, Is there any differences between in the level 1 roms? I see here there may be at least two versions https://www.trs-80.com/wordpress/zaps-patches-pokes-tips/rom-comparison-page-model-i/ I searched in vain, so would appreciate any insight. Thanks,

Well, I have a new crystal to test which is spot on at 10.6445 mhz (thank you Frank!). Unfortunately, it didn't fix the issue. When I removed the suspect original crystal, it checked out fine in my crystal checker. And replacing it with the new one made no difference. So, I figured the...

Here is an snapshot of my model 1 running the diagnostic image, stored in the free rom slot, selected via switches: The diagnostic image is available here: https://github.com/misterblack1/trs80-diagnosticrom

Thanks, a replacement crystal is on its way, will report back!

BTW: Here is how I ended up mounting the switches controlling the 4 banks of roms: Now that there is a diagnostic rom option, I'll have to re-do the labels.

I was checking out YouTube when this post from Adrian's digital basement caught my eye: a diagnostic rom image for either a m3 or m1: As I happen to have one free rom slot in my 4 bank adapter, this diagnostic rom is perfect! Although I don't currently have a ram issue (that I know of), this...

Thanks again for the suggestions: I did some more poking around based on the suggestions above. The PSU outputs have very low ripple (a few mV), so I don't think that is the problem. I carefully reflowed the solder on the crystal (twice), but it didn't make any difference. As far as I can...

Thanks for the suggestion, and lead on the crystal. I'm continuing to debug the problem and will report back! Much appreciated

Hi, Has anyone had good luck with replacing the power switches on their model 1 or Expansion interface? I've used these: https://www.digikey.com/en/products/detail/c-k/F4UEE/417520 The one I got for my EI has worked great (so far). Unfortunately, I've gotten two for my Model 1 and they both...

Hi everyone, I have a M1 that I've been trying to get working a bit more reliably. The latest issue I'm chasing is a flaky boot issue. The M1 boots intermittently. It is a rev-G board, with relatively few mods. What I've noticed is that when it fails to boot, I get garbage on the screen...

Well, I feel dumb. I spent a few hours debugging and swapping parts between monitors and computers. Before long I was able to get both of monitors to exhibit the problem! At this point I knew something was fishy. It then dawned on me that this might be simple rf interference. I unplugged...

Great, thanks for the pointer. I have been reading through the sams computerfacts for the model 1 as it has a section on the monitor. And thanks for the PM, very much appreciated!