Author Topic: Fluke PM6666 counter freezing after 3 seconds from turning on. (Read 11089 times)

pizzigri · « **on:** September 16, 2020, 10:24:04 am »

Ok, so I just received this counter from an Ebay seller. It looks brand new and has options pm9604 (gpib) and pm9607 (vtcxo). I connect it to mains and turn it on: it checks the display, passes whatever test it does at power-on, and works for three seconds. Then it freezes completely, with what ever option or command I managed to input in those three seconds. I tried connecting a function generator to an input, sending a 10mhz signal, and the counter actually works, for three seconds.... then it freezes up with the frequency displayed on the screen. Using 0.2s measuring time it samples the frequency until it freezes again. Does not matter if it starts from cold or after twenty minutes of being powered up.... i looked at it with a thermal camera and some chips do seem to run quite hot (around 50 C) but it should not be a problem. Can anyone help me?

PS: it seems the previous owner replaced the mains filter - that shows a trend of exploding- with a standard IEC socket and standard fuse.

Haenk · « **Reply #1 on:** September 16, 2020, 11:14:29 am »

My 6666 manual mentions a "local lock-out" function (GPIB only?) and a "display hold" function.
Not that I ever use those, but one of those might be the issue?

Here: http://na.support.keysight.com/pna/help/latest/Programming/GP-IB_Command_Finder/Local_Lockout.htm

Another thing I found is a service status request, which the counter sends out to attached GPIB units and requires a feedback (but gets none) - I'm sure some GPIB expert might help there...

pizzigri · « **Reply #2 on:** September 16, 2020, 11:53:25 am »

Thanks for the help, but it still freezes.... the command should lock out everything except the local key and that locks as well. Actually, even when locked out the display should show frequency of the DUT, instead it freezes as well, I just programed a sweep to test this.....
It’s driving me crazy

pizzigri · « **Reply #3 on:** September 16, 2020, 12:04:04 pm »

However, you ARE onto something! I pulled out the GPIB board, and the PM6666 is not freezing any more. Either it’s a broken option board or something to do with it.... I have never used it in my HP34401A, so I sincerely do not know anything about the interface. How can I troubleshoot the GPIB? I was indeed planning to use it. At least I know the counter works!

Haenk · « **Reply #4 on:** September 16, 2020, 12:42:09 pm »

Funny enough, the german and english manual differ in the "local" mode. The german manual states (translated) "If the counter is commanded via GPIB, it is possible to deactivate the LOCAL key by a command." Of course this command is nowhere mentioned. And this part is missing from the english manual (however that's the first edition, compared to third edition on the german one...).

tunk · « **Reply #5 on:** September 16, 2020, 12:45:57 pm »

If the eBay listing said it comes with a GPIB card,
maybe you could get a partial refund from the seller?

pizzigri · « **Reply #6 on:** September 16, 2020, 05:42:34 pm »

Quote from: tunk on September 16, 2020, 12:45:57 pm

If the eBay listing said it comes with a GPIB card,
maybe you could get a partial refund from the seller?

Well, it seems I’m stuck so yeah, since the listing did describe the unit as fully functional, I sent a friendly email to the seller describing the fault without filing a claim, so I’ll see how he replies.
Still beats me whether it’s some command that got stuck (?) or the GPIB board that’s broken. Is there any way I could troubleshoot it? Anyone actually use the GPIB interface of this fluke?

Haenk thank you that is most interesting! Maybe someone familiar with the instruction set for this protocol could chime in....

And thanks to everyone that helped!

Haenk · « **Reply #7 on:** September 16, 2020, 07:58:45 pm »

(sidenote: Got mine from ebay as "working", too. When powered up, it made noises like it was going to explode. Turned out to be the installed battery option, which failed to charge the loooooong gone NiCd battery. After removing the option, it worked fine. I really like the formfactor and ease of use.)

pizzigri · « **Reply #8 on:** September 17, 2020, 10:17:59 am »

BTW, does anyone have the complete service manual for the PM6666? Not the philips 48 page draft that floats around, the one that is supposed to have 120 pages by Fluke.
And again thank you to all that chimed in!
Franco

coromonadalix · « **Reply #9 on:** September 17, 2020, 11:08:25 am »

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjJgLHKhfDrAhWnUt8KHf5NDRoQFjAAegQIAxAB&url=https%3A%2F%2Fwww.vintageshifi.com%2Frepertoire-pdf%2Fpdf%2Ftelecharge.php%3Fpdf%3DPhilips-PM-6666-Service-Manual.pdf&usg=AOvVaw030wI2m3EeITr3s1VYs2Ui

has schematics in it ?

41 pages Phillips around 6 megs

Just uploaded to KO4BB, should be in the recent uploads ...

pizzigri · « **Reply #10 on:** September 17, 2020, 11:41:08 am »

Thank you Coromonadalix,

that is the draft I was talking about... I know that Fluke has an updated service manual for its version of the PM6666 (the one that officially supports 160 MHz instead of Philips' 120) that is over 120 pages long, and that is nowhere to be found.
That service manual is in fact branded Fluke....

schematics in the draft are good, however no silk screen, no part placement on the PCB and a pain overall the trace back parts on it....

FransW · « **Reply #11 on:** September 17, 2020, 11:59:51 am »

PM6666 operation manual (English) 1989.pdf, 2.8Mb, 70pages no schematics
PM6666 operation manual (English) 1996.pdf, 601kb, 46 pages, no schematics &
"What Happens When I Switch to Local?", page = 33
PM6666 service manual (English) 1989.pdf, 6,8Mb, 41 pages with schematics & parts list

PM me & suggest where to send (if any)

Regards, Frans

coromonadalix · « **Reply #12 on:** September 17, 2020, 01:22:41 pm »

i think the sv manual at 41 pages is the same as the one ive sent to ko4bb

FransW · « **Reply #13 on:** September 17, 2020, 05:05:49 pm »

From the Fluke 1996 Manual:
FLUKE , Timer / Counter , PM 6666, 4822 872 20017 7/October 1996

GPIB-INTERFACE OPERATION.............................. …….23
Introduction .............................................................. 23
What can I do using the bus? ................................... 23
Connecting the controller.......................................... 24
Giving the counter an address................................... 24
Checking the communication.................................... 24
Two ways of programming ....................................... 25
Syntax........................................................................ 25
Selecting output separator........................................ 26
How to select function.............................................. 26

GPIB address-selector Location ..................................5
GPIB interface-connector Location .............................5
GPIB-INTERFACE OPERATION....................................23 - 36

What Happens When I Switch to Local?
Switching to LOCAL causes the counter to adapt the set- tings indicated on the display, see ‘How to select function’. This means that the counter will never have settings in LO- CAL which are not possible to set via the front panel.
When switching to remote again, the LOCAL-setting will re- main. Bus-functions like SRQ mask, output separator, EOI, etc. will not be altered by switching to LOCAL and back again.
Summary of Bus Commands Function Selecting Commands

FransW · « **Reply #14 on:** September 17, 2020, 05:08:25 pm »

Manual (OCR) attached:

pizzigri · « **Reply #15 on:** September 18, 2020, 03:52:45 pm »

That is a wealth of information, thank you!
I will check it out immediately. Frans, I'll PM you immediately!

pizzigri · « **Reply #16 on:** September 18, 2020, 05:11:08 pm »

So. I found an ebay listing with the ever slippery service manual:
https://www.ebay.it/itm/PHILIPS-Timer-Counters-PM-6665-and-PM-6666-Service-Manual-2nd-Edition/324162530080?hash=item4b7997ab20:g:aiQAAOSwVkVeuMGp

I can't justify the price being asked though it is the one that is indeed complete (120+ pages), with this reference

PHILIPS Timer / Counters PM 6665 and PM 6666 Service Manual
90-10 2nd Edition
9499 465 01311

coromonadalix · « **Reply #17 on:** September 18, 2020, 05:30:05 pm »

@pizzigri or you buy it, and you ask for a few $$$ when people need the schematics

pizzigri · « **Reply #18 on:** September 18, 2020, 08:58:37 pm »

Quote from: coromonadalix on September 18, 2020, 05:30:05 pm

@pizzigri or you buy it, and you ask for a few $$$ when people need the schematics

Price + sh and duty is almost 60 Euro, too steep for me...

pizzigri · « **Reply #19 on:** September 28, 2020, 01:59:07 pm »

Ok, so I got a bargain Philips PM6669 with GPIB option installed. I figured I’d have a “quick-n-dirty” stand-alone counter for casual use and one for more serious work, connected to a PC.
Argh. The transplanted GPIB i/f board freezes the PM6666 just the same. When I mounted the, assumed broken, board from the original Fluke PM6666 on the 6669, no problem. At this point I am sure the fault lies in the PM6666, as it freezes no matter what, including connected or not , and besides it came to me that way from the seller.
There must be something that crashes exactly three seconds after boot. Self test is OK. Maybe the GPIB board init? Can someone point me in a direction? What to do? Unfortunately I am not a EE but just a hobbyist, so very complex things (and fundamentally equipment....) are a bit out of my reach.

coromonadalix · « **Reply #20 on:** September 28, 2020, 02:26:09 pm »

Agin i"ll say this, there is or was a service manual on ebay, it could help you pinpoint some problems if there is ... in the end you may loose more time than necessary or you put a value on you time ??

maybe it could be a firmware compatibility ?? a setting ? dip switch if there is one ?? i dont know theses counters

without the gpib card does it operate fully ?

pizzigri · « **Reply #21 on:** September 28, 2020, 06:48:33 pm »

Hi Coromonadalix,
I have the old service manual, the “new” one on Ebay is essentially an update though, and I have no idea what it includes. I will ask the seller. However, the manual is still 60 Euro delivered and that is a Lot for me... Selling copies would be unethical (and maybe illegal).

Anyway the problem I believe is in the counter and not in the board. So maybe the "old" manual may suffice.

Yes the PM6666 operates fully, smoothly and without any problem. I believe that it is something that failed in a previously working complete product; from the PM6666 sn, the GPIB card was installed at the factory. So it cannot be an incompatibility.

Also, I ruled out the card itself, it works in the other counter I just purchased on Ebay, and the PM6666 freezes with both cards.
So it MUST be the data path interface on the PM6666, I followed the path from the connector (labeled BU105 on the service manual) and I have three lines of interest: one is a 5mhz reference, and the other two are SCL and SDA (yeah, I2C bus) which go to a series of IC, I believe the three that could have something to do with the problem could be IC 101, 113 and 114, all labeled I/O (and all PC8574).
Both lines go to the CPU obviously (MAB8461P, with 6K ROM and 128 bit RAM), and to a custom IC, labeled IC 104 -CNT (controller?) an obscure OQ0501, built by Philips. This chip takes the 10 Mhz from the main oscillator and I believe divides it, as it supplies the 5MHz to the CPU and to the I2C bus. The 5MHz also goes to the GPIB card, where it is used by both the onboard CPU (another MAB84xx) and the GPIB IC.

BTW, it makes me think that maybe it could be possible to build a simple I2C to USB bridge to control directly the PM6666 from USB bypassing GPIB, however this is way beyond my possibilities - and I believe it wouldn't work all the same, since the problem is in the main board anyway.

Now what to do?

coromonadalix · « **Reply #22 on:** September 28, 2020, 10:51:08 pm »

ok hum transplanting parts could be problematic .... maybe a bus buffer or your strange parts numbering ?

FransW · « **Reply #23 on:** September 29, 2020, 10:29:37 am »

I have a good readable and copyable service manual on the way.
A paper copy.
Please inform me about the uncertain info so I can attach it here.

I will check my PM6666 GPIB card and version.

Regards, Frans

coromonadalix · « **Reply #24 on:** September 29, 2020, 10:40:57 am »

Would be nice to host it on Ko4bb website if you can ? It would help the community


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Author Topic: Fluke PM6666 counter freezing after 3 seconds from turning on. (Read 11089 times)

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