Recent content by cruff

What is the 112926.jpg trace?

Is C12 good? What does the BSCK signal look like at pin 8 of the 74LS14? Is there any voltage differential between GND at pin 7 and the GND at pins 1 and 4 of connector J1 where power is fed to the display board? Is the keyboard that you had disconnected the button matrix at the bottom of the...

If you disconnect the keyboard will the unit come up enough to see the same signal being routed through the 74LS14? Does that signal improve then?

The voltage levels on the output of the 74LS14 don't look right, they should not go negative unless the ground of the scope probe wasn't really at ground like the trace on the input side. Also that low to high signal transition isn't good. Can your replace the 74LS14?

I haven't gone back and reread the whole thread, but have you resoldered the DOC II chip's pins (or those of its socket)? Have you checked the caps in the power supply? Are any of those leaking? Is there noise on the power supply rails?

You should also check for bad solder joints, a microscope or magnifier (or magnifying camera) might be necessary. It may be possible when you cleaned it a bad joint opened up.

Gotta love those spinning tapes to show things are happening! Thanks for the post.

Had to do that to install my Qprobe 2023 into my BA23. DEC certainly didn't make it easy to do stuff quickly inside the enclosure.

For completeness:

Do you have an addressing conflict between the rqdx3 and the dhu11?

Do you perchance have another emulated device on the Qbone that might be causing some interference? What happens if you move the Qbone after the other devices?

A specific model of CFL may actually be driven at a higher frequency than the AC line if it has a switching power supply in the base.

I took a look in my BA23 power supply a while back thinking I'd need to change out soon to fail RIFA caps, but found a different brand in there that used a different encapsulation material. Looked at my VAXstation 4000/60 and didn't find any RIFAs in there either.

I built a PC532 years ago and had Minix running on it, I didn't end up using it much and I no longer have the hardware.

Are they 1/2" tape reels? Something else? Further description or pictures would help.