| Electronics > Repair |
| Fluke PM6666 counter freezing after 3 seconds from turning on. |
| << < (18/27) > >> |
| thinkfat:
It seems attaching the screenshots didn't work, however, I have a general advice on probing with an oscilloscope: Don't use a far-away ground point for probing. Don't use the frame as ground, in particular. Find a ground hook on the PCB or something similar. And of course, use the oscilloscope probe and nothing else. EDIT: there's obviously a TP100 next to IC104. It has a pin labeled "GND", connect the oscilloscope probe's ground lead to this pin. Put the probe tip directly on the chip pin. EDIT2: IF the waveform we see is real (which I doubt when I see the probing setup), it looks like the output driver on the clock output of IC104 is damaged. The high-side mosfet might be dead or deteriorated. It looks a bit like the recent "Intel Atom C2000 bug" that killed thousands of NAS, switches and other appliances. Maybe a similar "fix" could be used: You can try pulling the clock line up with a small resistor (200 \$\Omega\$ or something). |
| Dr. Frank:
Hello pizzigri, maybe it's a silly question.. have you ever attached the GPIB to a PC interface and tried to steer the PM6666 from there? Reading through this thread, I am under the impression, that you never tried that. I'm only asking, because I used a PM6669 with GPIB many decades ago, and I'm not sure if that was required also. Frank |
| pizzigri:
Hello Dr. Frank! the device freezes whether I connect a GPIB cable or not. However, I also have other devices with GPIB, a Philips PM2534 DMM, a HP34401A and of course the smaller sibling to the PM6666, exactly a Philips PM6669 which never showed the problems this one has. |
| 0xdeadbeef:
Mainly to get updates on this thread automatically: I also bought a PM6666 for cheap quite some time ago and it locks up (no reaction to key presses) occasionally directly after startup (probably three seconds, didn't measure that). Originally, it worked most of the time, lately, I needed to start it a few times to avoid it locking up. So this seems to be something becoming gradually worse. Never really looked into this as I upgraded my Tabor counter in the meantime and even if I needed the PM6666, I got it to work after a few trials. |
| pizzigri:
Ok, so here’s the updated measure. Did as told (thank you Thinkfat) and I do get a cleaner wave but it is still a sawtooth. |
| Navigation |
| Message Index |
| Next page |
| Previous page |