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Old 13th Dec 2016, 8:09 am   #21
skysat2
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Default Re: Philips PM5544 Faulty

I need really someone who check my Circle-Board with a Oscilloscope. I have really no experience...
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Old 13th Dec 2016, 8:46 am   #22
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Default Re: Philips PM5544 Faulty

Skysat2,

The way it has to be checked with a scope is plugged onto an extender board (if the access is difficult) and running in your unit. But I guess if someone had an identical unit to yours, you could send them the circle board, if they were agreeable, to test it. But its also possible that the fault is not on the actual circle board itself and its not getting the right signal from elsewhere in the unit.
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Old 13th Dec 2016, 9:21 am   #23
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Default Re: Philips PM5544 Faulty

Hello Argus25,

Quote:
Originally Posted by Argus25 View Post
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.

Its not the only thing needed for repairing video circuits. Good instrument for do it must have minimum Video/TV-H & -V triggering capability too, bether if it has a "Lineselector" too...
Karl
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Old 13th Dec 2016, 12:07 pm   #24
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Default Re: Philips PM5544 Faulty

Karl,

At least with the minimum of the delay time-base its possible to inspect the vertical blanking and sync intervals well and individual lines even though the line number might not be known (unless you count it) and easy to check odd and even fields.The simple compact Hitachi V509 scope has the TVH and V sync options too.

Some tek scopes had TV triggering you describe too as an optional feature pcb, but I have practically never found the call for it fixing VCRs/cameras or time-base correctors & digital effects generators etc. The delay timebase (if used properly) is all that is needed with a dual trace scope, mostly. The tek 2465B can display 4 traces which is handy.

I haven't warmed yet to the new generation digital scopes, great for math functions and data storage, poorer for actual displayed waveforms compared to the masterpiece of electron optics that is the CRT in the 2465B.

For example the Tek 2465B even though it is rated to 400MHz can sync lock a 900MHz waveform and visualize it, even though the amplitude is meaningless. A 400MHz bandwidth digital scope can't do that, plus they give pretty hopeless results compared to the analog scope on and after rising edges when tested with a tunnel diode pulser (in my opinion).

The 2465B's though develops battery NVRAM problems and lose their calibration data when the internal NVRAM battery goes flat which is long re-calibration process. I found a way to replace these with FRAM (Partly because someone said it couldn't be done, and that's enough inspiration and a red flag to a Bull to want do it).

Not many know that Ramtron, the people who invented FRAM, were an Australian company that later moved to Colorado Springs (Nikola Tesla's old stomping ground). The story on how to put FRAM into Tek 2465B scopes is here, if you were interested:

http://worldphaco.com/uploads/TEKTRO...THE_DS1225.pdf

Last edited by Argus25; 13th Dec 2016 at 12:14 pm.
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Old 13th Dec 2016, 1:47 pm   #25
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Default Re: Philips PM5544 Faulty

Hi Argus,
I agree with you (time ago I worked in vidcam development too), a DTB-scope can be OK for measurements on vid-signals_ if somebody can use it, knows some/a lot over vid-sync-systems and it triggers properly...
Dont forget please, our thread opener dont have only a simple `scope
Btw; best thanks for the Tek script_I know Ramtron & FRAMs from hes beginning _ its a good/profi job!
Best regards _ Karl
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Old 13th Dec 2016, 9:53 pm   #26
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Default Re: Philips PM5544 Faulty

Hello Skysat2
Please find attached a copy of the block diagram of the PM5544. On page 30 (Basic Signals) you can see where the signals come from and go to and which IC’s (Integrated Circuits) are involved in the signal path. In the fifth block down you will see a white horizontal and vertical line on a black background, this is missing in your first picture and is also twice the width it should be and has moved all the other blocks down by one vertical block. It starts at V15 but finishes at V19, not V17 and the white horizontal line on V16 is missing. This may point to a fault on the Circle Grid PCB and any one of the IC’s in the signal path could be the cause. I also mentioned that the Centre Cross was also missing and this may give a clue to something common to both signals and may narrow the fault down further.
On page 33 of the PDF it mentions in section E a Test Output Amplifier, have a read of this section and see if you could use this facility and I will see if I can find suitable points to test, to pin the faulty area down.
Regards Stan.
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File Type: pdf Philips PM5544{Part 1}STS.pdf (1.01 MB, 267 views)
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Old 16th Dec 2016, 5:19 pm   #27
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Default Re: Philips PM5544 Faulty

I have now Order some IC's (8000 Series) to try out on the Circle PCB.

Today I have a 1 pin with adhesive tape on UNIT 02 over, and the result can be seen in the photo. You can see an expanded Pattern section. I will replace the nearest IC connected to this pin - to test.


Anyway, if anybody can Check my PCB professionally, please send me a PM.
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Old 16th Dec 2016, 9:55 pm   #28
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Default Re: Philips PM5544 Faulty

Hello skysat2
Thanks for the pictures. By insulating pin1 on the circle memory board you have removed the 5 volt supply to the board, please be careful as the +15 volt supply and -10 volt supply are still connected to the board. If I remember correctly you can remove the board and the unit will display the first image you have posted.
From the picture you have posted I am sure that there is a fault on Unit 5 (Vertical Decoder) as the timing is wrong and not displaying a horizontal line at the centre of the screen V16 and the lower castellation are also missing at V29. If these signals are wrong it will upset the start and stop signals to the Circle Memory board and it will not be able to display the circle. The IC’s to check are IC 18 (7450) and IC 19 (7400). I will scan this service information for this board and post it later.
You could try using the test amplifier with your monitor connected to BNC socket “X” on the rear of the unit to prove the point. You will have to solder a wire to the input terminal 14 on Unit 15A and connect it to the signal lines on the back plane to prove a fault on Unit 5.
Regards Stan.
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Old 17th Dec 2016, 12:24 am   #29
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Default Re: Philips PM5544 Faulty

Hi Stan

I have expressed myself wrong, i have insulated PIN3 on the left side of the PCB. (This is misleading because twice the same pin-numbers are used all over the PCB).

Thanks for your Text above, i will this try on Sunday.
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Old 17th Dec 2016, 11:19 am   #30
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Default Re: Philips PM5544 Faulty

Hello Skysat2
Please find attached PDF copies of the Circle Memory and Vertical Decoder PCB service information.
Please check this information matches what PCB’s are fitted to your unit, as I said earlier there are at least four different versions of these units and many modifications have been done over the years.
Have a look at the back plane wiring diagram Fig.XIII-2 (Page 58) and you will see a key to the markings on the PCB edge connectors.
Isolating pin 3 on the Circle Memory PCB isolates a signal from Unit 5, Vertical Decoder PCB so this may have isolated the faulty area to the Vertical Decoder PCB.
Regards Stan.
Attached Files
File Type: pdf Philips PM5544 Circle Memory STS.pdf (306.4 KB, 220 views)
File Type: pdf Philips PM5544 Vertical Decoder STS.pdf (633.6 KB, 226 views)
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Old 17th Dec 2016, 4:06 pm   #31
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Default Re: Philips PM5544 Faulty

Hello Skysat2
Please find attached a PDF copy of the Test Amplifier Unit 15A service information.
Regards Stan.
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File Type: pdf Philips PM5544 Test Amplifier STS.pdf (47.1 KB, 187 views)
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Old 17th Dec 2016, 11:20 pm   #32
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Default Re: Philips PM5544 Faulty

Thank you very much Stan for your Information

Now i have make some test probes back on the Device with the Test Amplifier. See the attached Photos. You can tell me, which Pins i should test.


I have written the name from the test-points into the Filename.
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Old 18th Dec 2016, 9:42 pm   #33
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Default Re: Philips PM5544 Faulty

Hello Skysat2
Using the circuit diagram for Unit 5 Vertical Decoder try connecting the test lead to terminal 54, this is the output of IC 19/1 one of the suspect IC’s. Also check the inputs to the 16:1 Divider on terminals 12’ 13’ and 19’. These may be OK signals as the divider signals are decoded by IC6, 7 and 10 and fed to the suspect IC’s 18 and 19. Unfortunately without a board extender there is no easy way to check these signals.
The pictures show that the fault is before units 8 and 9 so try these tests first and if there is nothing conclusive, perhaps the next step will be to change IC 19 7400 (Quad Dual Input NAND Gate) first and then IC 18 7450 (Dual 2 Wide, 2 Input AND -OR- INVERT Gate).
Regards Stan.
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Old 19th Dec 2016, 7:19 pm   #34
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Default Re: Philips PM5544 Faulty

Hello Stan

I will replace the IC18 and IC19 on the Unit 5 soon. Then I will continue to report.

At the Bottom, i've attached the Photos from the diffrent probes that you wrote. At Terminal 13' and Terminal 19' it shows just a Black Screen.

Regards Skysat2
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Old 19th Dec 2016, 9:15 pm   #35
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Default Re: Philips PM5544 Faulty

Hello Skysat2
I assume that the first picture is with the test amplifier connected to terminal 54 an unit 5. This shows 14 lines which are generated by the vertical divider so this appears to be working. However the line at V16 is missing, which is decoded from signals from the divider by IC 18 and IC19. Could you check to output on terminal 9 from IC19/3 and see if you get a single line at the vertical centre of your monitor screen? Also could you reduce the height of the picture on your monitor to make sure there is nothing lost off the lower part of the screen, for example the lower castellation.
I am still not sure how the central black band is two blocks wide instead of only one and why this is moving all the other blocks down the screen. You could try connecting the test amplifier to the terminal numbers as shown on the right hand side of the Unit 5 diagram, these should show blocks of different heights corresponding to the V signals, as marked next to the terminals and at different positions on the screen of your monitor.
Compare the results with the chart on page 29 (Fig. V1-1) I am looking for V16 which is half way between the block V15-V17.
Regards Stan.
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Old 6th Jan 2017, 12:23 pm   #36
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Default Re: Philips PM5544 Faulty

I have difficulty getting the parts. What is the difference between the IC "DM7400N" and "SN7400N" ?
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Old 6th Jan 2017, 12:51 pm   #37
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Default Re: Philips PM5544 Faulty

The DM7400N was manufactured by National Semiconductor and the SN7400 was manufactured by Texas Instruments. Both are quad 2 input Nand gates and are pin compatible. You can use either.

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Old 6th Jan 2017, 6:32 pm   #38
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Default Re: Philips PM5544 Faulty

Hi Skysat,
You can buy such "7400" type, only important is hes package-in your case I think = DIP14 (Dual-Inline, 14 pin)... Farnell-ch or Distrelec has surly lot of version, or Pusterla in ZH too. http://www.pusterla.ch/
Karl
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Old 8th Jan 2017, 2:02 pm   #39
skysat2
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Default Re: Philips PM5544 Faulty

Thank all for your Input.

@Stan
I've replaced now the IC18 & IC19 on the Unit5, but without success :-( It stay on the same Picture fault... Any more idea?

Regards skysat
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Old 8th Jan 2017, 6:33 pm   #40
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Default Re: Philips PM5544 Faulty

The lower Castellation is also missing.
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