Electronics > Repair
Fluke PM6666 counter freezing after 3 seconds from turning on.
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pizzigri:

--- Quote from: Ordinaryman1971 on September 30, 2020, 08:07:05 pm ---Far fetched idea but... maybe your firmware is somehow corrupted. Let me see if I can burn the copy of of my counter.
Could you see the version you're running?

I know it's silly for me to ask... but did you inspect everything for possible shorts... the seller stated that the meter is working fine.. so, lets assume that he did in fact turn it on and it was working, then... something happen in transit.

What is the frequency of the prescaller you've had installed... can it go more than 1.1 GHz, that's what I have in mine. Actually I've tested mine some time ago and it goes all the way to 1.6GHz.... and I have standard time base btw..

--- End quote ---

Ordinaryman1971....
do you have a PM6666?
I checked spec sheet of the MAB8461P cpu, it has Mask ROM therefore impossible to retrieve or program for that matter.
Can Mask ROM corrupt???? I find it unlikely, but hey could be.
I still hope it is something else.
pizzigri:
Additionally, I have run the Logic analizer on the surely working PM6669 counter, and I found that it is mostly silent: the bus stays completely quiet in high until a button is pressed or something else happens, and this, even including the GPIB board installed.
At startup it does a routine check of everything and then just stays listening.

The PM6666 is always "talking", but that could be because of the DAC? This component is not included in the PM6669.
pizzigri:
coromonadalix, looking at these info obtained with the Saleae clone, do you think that what you suggested could be true?
All my best, Franco
coromonadalix:
Strange bug i may say,   since i dont have the full schematic, i dont know if there are bus buffers, buffer with a latch / enable  etc ...


The i2c should be relatively easy to read,   i dont know wich software you use or witch version ??  normally you have the bus decoding option in it ?  i recall you have 2 compatible software who works with the clones ...

Could be the MAB8461P who's corrupt at one specific place when the gpib card is there, gpib protocol / enumeration, say a single bit ???

The best would be to have anoter 6666 and try this chip in the other ...

Or  the last option is to sell it "with the gpib not working warning" and try to find another 6666 ?


Your excel sheet  show  lots of "missing ack"   (acknowledge) ??
Ordinaryman1971:
I do have two.. they work like  a charm. One with gpib and C channel 1.1GHz second without C channel, both with regular oscillator. Let me open it up and see.... I also have a spare gpib port from 6680B.
Here are pictures of both before and after backlight hack.
It’s not perfect but it will do...
I will open it up later today and get a look.
Odd question... what's the address on your GPIB card... try different setting.... like first or the last address.
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