Philips PM6662 Service Manual

[yngndrw]

Hello all,

Just wondering if anyone has a link to the service manual for the PM6662 frequency counter ? I've found some for sale online but the price is way too high, I'd prefer free.

My counter is working fine but I was thinking of changing the oscillator and adding some of the other options like the 1.3GHz input. Someone has already added an OCXO to the PM6665 (http://www.jackenhack.com/philips-fluke-pm6665-pm6669-ocxo-pcb/) but the PM6662 seems to be different - The standard oscillator is not a separate board and the silkscreen suggests I need to remove the crystal. I wanted to check over the schematic to be sure.

Thanks.

[SaabFAN]

I would suggest to build a small separate box with the ovenized oscillator in it. It would also give you the opportunity to later add a GPS-Receiver to it to achieve even higher accuracy.

About the 1.3GHz option: You should check if the counter uses the PM9610 as the input-module. I have designed a board that replicates the function with modern components.

[yngndrw]

I was actually thinking of doing both to be honest, fit an OCXO internally for convenience and then have a separate OCXO-GPSDO as a more accurate reference on the bench. Thinking about it though there might be limited benefit in having both so maybe I will just build a separate reference.

As for the 1.3GHz option, the datasheet lists the option as PM9608B sadly which seems to be used right across the PM666* range. I have no idea what the difference is, but the PM6662 mainboard looks to have a totally different layout to yours sadly.

[DaJMasta]

Have you tried looking around for PM666x counter guides?  I'm unfamiliar with the series, but Fluke seems to be pretty good about making service manuals and a lot of it is available - I know there are some meters that look a bit similar from the front, so if they just depopulated a couple chips and used lower rated ones for another bit, maybe it's the same board and overall layout of a higher end, same series counter.  In fact, looks like the fluke/phillips PM6665 and PM6669 have 1.3GHz options and at least the 6669 has a similar front panel layout - could be a good resource if there's documentation or parts available for those.


That all being said, you may not need a proper service manual to do what you're looking for.  Depending on the layout, the optional input could just be an expansion card (it is for my Fluke counter and I know it was with some of their Fluke/Phillips counters), so then you'd just need to find the card which could be available.  For the OCXO, it should be real easy to find the current crystal and remove it - then you can just bodge in a new one however you want.  It starts getting more complicated if the board already has an external feedback loop and software to give you warm-up time notifications or something, but the oscillator itself you can set up with just a few components on a breadboard if need be.  Given the cost of the oven and board you'd have to build, a cheap GPSDO may be a better choice unless you absolutely need the counter to be portable without the GPSDO setup time and pieces.... it would probably only be 4x more expensive or so than the OXCO alone, and it's a higher precision reference and something you can feed into other instruments if you've got them.

[yngndrw]

For some reason Philips seem to have used a different mainboard for each one, the entire layout is different for the PM6662 with only the input section resembling the same layout.

The only service manual I can find covers the PM6665 and PM6669:
http://www.jackenhack.com/slask/pm6665_pm6669.pdf

From what I can tell, the oscillator pinout seems to be the same but as I say the whole board layout is different. Also it looks like the PM6665 has its standard oscillator on a separate board which can be seen here, but the PM6662 has it on the main board with a note to remove the crystal if using the plug-in board: (But it isn't 100% clear if you just remove the crystal or if you have to remove other components like the trimmer)
http://www.jackenhack.com/wp-content/uploads/2015/12/old-oscillator-1-580x365.jpg

The best resource I've found is Jack Zimmermann's blog as I've been linking to, with some details of his upgrade here:
http://www.jackenhack.com/philips-fluke-pm6665-pm6669-ocxo-pcb/

I think I'm going to have to go over the schematics in the PM6665/PM6669 service manual and see how close they are to my board. I think the options are compatible but I don't know for sure. The PM6662 is quite basic so it doesn't have any indicators for warm-up times. (It doesn't have an OCXO at all as standard)


Like you say, I might just be better off with an external unit - Maybe even a Rubidium oscillator if I'm going that far. I'll have a more detailed look over the other service manual and see what I can work out from it.

Edit: I don't know how I missed it before but the PM6665/PM6669 service manual includes the schematics for the various options as well as board layouts and these have the correct option numbers, so I think I should be able to work from them. I didn't notice the options in there last time I looked.

[jackenhack]

You could just take out the old card and check which pins goes to the XO and which ones is +5 volt and GND. I'll have a look around to see if I can find the service manual for the PM6662.

Thanks for the links by the way! 

Jacken

[yngndrw]

Thanks Jack, that would be great. Your site was the only place I found with the PM6665 service manual so it looks like you're better at finding manuals than I am !

There isn't an old card in the PM6662, the standard oscillator is soldered into the main board with a bit of dodgy silkscreen text saying to remove the crystal if the option board is fitted - Meaning that the various capacitors are kept in circuit. The connector does look to have the same pinout as the PM6665/9 though, when I checked it over.

Here's a picture of the PM6662, you can see how the layout is different and the on-board crystal:
https://s14.postimg.org/4le0gq3m9/PM6662.jpg

[tabajaralabs]

Does anyone has the OPERATOR manual for the PM6665? Thanks!

[yngndrw]

Does anyone has the OPERATOR manual for the PM6665? Thanks!

Here's the operator manual for the PM6666, which I believe to be very similar:
https://www.eevblog.com/forum/repair/fluke-pm6666-counter-freezing-after-3-seconds-from-turning-on/?action=dlattach;attach=1068770

Also here's the datasheet for the PM6665 if that's of any use:
http://www.testequipmenthq.com/datasheets/PHILIPS-PM6665-Datasheet.pdf

[tabajaralabs]

Thanks, I already found these on the net. The 6665 is somewhat different, but I'll use the 6666 manual while not found...