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Old 4th Dec 2016, 10:58 am   #1
skysat2
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Default Philips PM5544 Faulty

Hi there.

I bought an Original Philips PM5544 Testcard Generator, but the Circle doesn't display anymore. It just flickers. I have now replaced the capacitors on the Unit U02, but without success.

Have anyone an idea?
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Old 4th Dec 2016, 3:26 pm   #2
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Default Re: Philips PM5544 Faulty

It's not something silly like dirty switches?
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Old 4th Dec 2016, 3:54 pm   #3
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Default Re: Philips PM5544 Faulty

The switches are OK! It's really strange.
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Old 5th Dec 2016, 7:02 pm   #4
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Default Re: Philips PM5544 Faulty

The fault must be on this plate:

The two blue Capicators are already replaced.
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Old 6th Dec 2016, 10:04 am   #5
Malcolm G6ANZ
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Default Re: Philips PM5544 Faulty

As it's a plug in board, are the edge connections clean and making good contact ?

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Old 6th Dec 2016, 11:45 am   #6
skysat2
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Default Re: Philips PM5544 Faulty

Yes, I've cleaned the Connector on both sides. I've now ordered some new IC's for this Platine.
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Old 6th Dec 2016, 12:36 pm   #7
kevinaston1
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Default Re: Philips PM5544 Faulty

I have a vague recollection of an article in Practical Television about a circle generator fault on a Philips PM series. If I remember correctly, it had a description of the circuit operation; and the problem was something to do with vey close tolerance capacitors.

Perhaps a member may have a copy of this.

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Old 6th Dec 2016, 2:26 pm   #8
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Default Re: Philips PM5544 Faulty

Yes, I would be very thankful for more help
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Old 6th Dec 2016, 9:51 pm   #9
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Default Re: Philips PM5544 Faulty

Hello Skysat2
There are a number of different versions of the Philips PM 5544 colour pattern generator and from the picture of the circle memory PCB, your unit is one of the later types with the circle data held in an EPROM instead of the earlier core memory type. Before you condemn this board as faulty can you check the following and compare with the attached pictures.
First if you release the {COL DIFF NORM} pushbutton and press the {GRID ONLY} pushbutton do you get a picture like the fourth image attached?
Second if you now press the {COL DIFF NORM} pushbutton do you get a picture like the fifth image?
Third if you now press the {EXT PICT} pushbutton do you get a picture like the second image?
Also do you have the service information on the PM5544 and a test meter and oscilloscope?
Regards Stan.
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Old 7th Dec 2016, 8:54 pm   #10
skysat2
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Default Re: Philips PM5544 Faulty

Hello Stan.

Thank you very much for your Help! Yes, I press all Buttons, through the procedure that you wrote it. But it is really wrong with this Device...

Quote:
First if you release the {COL DIFF NORM} pushbutton and press the {GRID ONLY} pushbutton do you get a picture like the fourth image attached? Yes
Second if you now press the {COL DIFF NORM} pushbutton do you get a picture like the fifth image? Yes
Third if you now press the {EXT PICT} pushbutton do you get a picture like the second image? No, it shows not a Circle.

I have a simply test meter, but I haven't an oscilloscope.

I have filmed this Sequence from my Monochrom-Monitor: http://homepage.hispeed.ch/skysat/video.mov

Last edited by skysat2; 7th Dec 2016 at 9:07 pm.
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Old 7th Dec 2016, 9:51 pm   #11
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Default Re: Philips PM5544 Faulty

Hello Skysat2
I think the first thing to check is the Power Supply output voltages are within the tolerances as shown in the attached PDF copy of the manual. These voltages can be checked on the back-plane of the rack please see attached pictures, or at the emitter connections of the power transistors mounted on the rear of the PCB rack.
The voltages across the three electrolytic capacitors mounted on the rectifier PCB at the top left of the picture of the back-plane should also be measured with a dc voltmeter and compared with the values on the drawing.
The next step is to measure the ripple voltages across these three capacitors using your test meter on an AC VOLTAGE range. The expected ac voltages measured should be in the order of a few hundred milli volts. If any of these voltages are higher than this it may point to a low value capacitor or a part open circuit bridge rectifier.
Please try these tests first and tabulate the readings.
Regards Stan.
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Old 8th Dec 2016, 12:54 am   #12
Peter.N.
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Default Re: Philips PM5544 Faulty

Never actually seen one of those before - heard of it of course, what a work of art, I would have loved one of those in my working days.

Peter
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Old 8th Dec 2016, 5:26 pm   #13
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Default Re: Philips PM5544 Faulty

Hello Peter
These test card generators were years ahead when first introduced in the early 1970’s. They are full of 7400 series TTL logic and the A to D converters are made up by switching weighting resistors in and out using dual transistors and the circle memory was a core type, which only stored a quarter of the circle. The complete circle was obtained by reading the memory forward and backwards and inverting to obtain the complete circle, all done in TTL logic synchronised from the master clock and the horizontal and vertical dividers using dual D positive edge triggered flip flops.
They are certainly a work of art and it is amazing that so many are still working after all this time.
Regards Stan.
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Old 9th Dec 2016, 11:42 am   #14
Peter.N.
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Default Re: Philips PM5544 Faulty

Thanks Stan. I would imagine they cost a fortune, I had an ordinary Labgear pattern generator that I bought from one of my ex rental TV suppliers - probably from someone Granada took over, I thought that was good.

I started to loose the plot about the time digital electronics came about, still understand valves best

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Old 11th Dec 2016, 11:14 am   #15
skysat2
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Default Re: Philips PM5544 Faulty

Thank you very much for your assistance. Now I test all voltages on the capicators on the Unit 01, that you describe. One of these Capicator had a too high Voltage, i replaced them.

But all without Success. The Circle doesn't display..


(Should I also try replace all 7400 Series to the 8000 Series on the Circle-Board? Is that a good Idea?)
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Old 12th Dec 2016, 1:55 am   #16
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Default Re: Philips PM5544 Faulty

Skysat2,

That is not a good idea to start replacing all the chips. In replacing chips there is always the possibility of some pcb thermal and track pad damage, and things can go badly awry with multiple faults if a new part you insert in this process is defective. Its a risky approach likely to end in trouble and if it succeeds, never really knowing what the original fault was.

If a single chip can be definitely identified as defective on fault finding with the scope then its pins can be cut close to its body, the chip sacrificed and the pins carefully removed one by one from the pcb with less thermal stress on the pcb pads and plated through holes than using a solder sucker or wick and attempting to preserve the IC by removing it intact. The pcb is more important than an individual common garden IC, but for a special IC that's not the case.

Plus its a real shame to replace original working vintage date code TTL IC's that have nothing wrong with them.

It is much better to go through the circuit patiently with the scope to try to find the section of the circuit and the exact component that has failed, it may well just be one gate in one IC most likely. Its worth spending the time studying exactly how the circuit works, that will make it easier to locate the faulty component or connection. You will need to manufacture a card extender if you don't have one probably.

I have some Philips pattern generators of a slightly later vintage and they are based on wonderful LS series TTL, also generate a circles using an interesting approach based on a parabola. The quality of this sort of gear is not seen today, so it must be preserved as best possible. You are lucky to have such a wonderful apparatus.
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Old 12th Dec 2016, 2:53 pm   #17
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Default Re: Philips PM5544 Faulty

I have almost no experience in such things. Could someone from the forum measure some pcb boards? It will be great! I will of course pay the postage, even for the work and material.
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Old 12th Dec 2016, 9:49 pm   #18
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Default Re: Philips PM5544 Faulty

Hello Skysat2
I have to agree with the comments of Argus25, perhaps he was not aware that you did not have an oscilloscope to do some of the signal tracing needed to pin down the faulty areas.
I have noticed from your first picture that there is a horizontal line missing in the black area between the colour bars and the multi burst frequency gratings as well as the centre cross this may point to a logic fault on the Cross Gate PCB. Compare the image with the rather poor image of the complete test pattern. As the unit will display the grid pattern this proves that the master clock, the vertical and horizontal dividers are working, but these signals are used on all the other boards to generate the vertical and horizontal position of the various parts of the test pattern and a fault on any printed circuit board (PCB) can reflect and upset the timing on other boards, this is where an oscilloscope is essential to check the timing an amplitude of the various signals.
I agree with you that the fault may be on the Circle Memory PCB, but the most likely fault could be a PROM fault and if it is I doubt if you will be able to obtain a Prom with the correct circle program pre programmed.
Please leave this with me for a few days and I will see if I can find the correct service information for the suspect boards and I will try and pin it down to a few TTL chips to check. Please note these units are all fitted with the original standard TTL chips which have a high fan out and in most cases cannot be replaced with the later LS (Low-power Shockley) versions.
Regards Stan.
PS. Please find attached a PDF copy of the operating instructions.
Also please DO NOT ADJUST any of the preset controls.
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Old 12th Dec 2016, 10:38 pm   #19
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Default Re: Philips PM5544 Faulty

Hello Stan.
Thank you for your contribution. I'm pretty sure the fault must be on the TTL Logical Chips on the Circle Board.

I've tested, if i stick just the left side of the Connector Board into the Contact, the Testcard show's more from the Picture left & right. no limited trough the Circle. (It's a shame, i know but i have no other Choice). I will make a Photo tomorrow.


Yes, i'll be pleased more to hear you.

Regards Skysat2
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Old 13th Dec 2016, 2:17 am   #20
Argus25
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Default Re: Philips PM5544 Faulty

Skysat2,

I saw from your post you didn't have a scope, but obviously if you want a reasonable chance of repairing this yourself you would need to hire,buy or borrow a scope.

It is not really possible to trace the functions of the logic circuits & signals in video gear without one. You are essentially working blind without one. There are plenty on ebay cheap and if you got one you wouldn't be stuck next time if a repair problem comes up.

Forum members could always comment on the better scopes for video work. Everyone tends to have a favorite they like.

One particularly good cheap 80's vintage and very compact scope, good for video work ( because it has a delay timebase) is the Hitachi V509.

In my workshop I generally use scopes like the Tek 2465B (but these are costly 400MHz jobs) or the Tek 464 which is 100MHz capable. But there so are many to choose from. There are also plenty of good used Philips scopes about too. As for new scopes there are plenty of entry level digital scopes now.

There was a type of clip on logic probe for TTL IC's with LED's to indicate if pins are high or low. Unfortunately these sorts of things are only very good for circuits with static/stable signals or slowly changing ones. For anything with high frequency signals a scope is the only way.
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