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Old 13th Nov 2017, 11:25 am   #21
Vintage Engr
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Default Re: Philips PM5519 Service info

Quote:
Originally Posted by dazzlevision View Post
Quote:
Originally Posted by Vintage Engr View Post
Incidentally the early copy of the manual I have does not show the modification, so any further info on that wouild be appreciated.
Hello,

My PM5519 service manual has this printed on the front cover:

(9499 525 00711) 800201/2/01-03.

I also have a supplement ref. SGS 27, which covers several changes, but nothing that is likely to relate to your problem. I can scan it, and post in this thread, if you wish.

The supplement SGS 27 lists other supplements that had already been published: SGS 13, SGS 20 and SGS 25 (which I do not have).

However, the supplement I do have came with the PM5519 service manual that I ordered from Pye Unicam, circa 1983. It's therefore likely that these have already been incorporated in the service manual that I have (but not certain!).

These supplements cover changes/corrections/additions to both the PM5519 Operating and Service manuals.

In case it is relevant to your hash/noise problem, there is a wiring mod shown on the layout drawing of the main PCB. I posted scans of this earlier in this thread, but only part of the track layout change is shown, so:

wire 387/1-395/3 added

connection 395/2-395/3 separated.
Thanks, you're gem!

I've just made coffee & come back into the workshop, having left the PM5519 on to warm up.
I will have a look at the that info again now, it wasn't obvious what that wiring change was there for.

David.
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Old 13th Nov 2017, 11:37 am   #22
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Default Re: Philips PM5519 Service info

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Hi,
this thread is being very useful and informative, as I have a PM5519 to investigate sometime....
but it is in the round tuit pile !
Yes, I think we're all learning something from this.

My PM5519 is an ex-Germany version, suffix 'GX', so it has an additional board with the Zweiton stereo audio.
I'm hoping, once I've fixed all the faults, to convert this to conventional 6MHz intercarrier sound.

Like you, I have a number of items of test gear in the ''A round Tuit" pile, including a nearly brand-new 'scope that I'm trying to repair to save having to send it back to China, that failed whilst I was working on the PM5519..

Murphy's Law!

David.
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Old 13th Nov 2017, 11:54 am   #23
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Default Re: Philips PM5519 Service info

I like that, what he presumably meant was that the PM5519 was built to a price, rather than a specification.
Having just gone back to the pages of the manual that you very kindly scanned earlier, & then relating these wire changes to the board, - it's not obvious what they mean.
Presumably somewhere in the manual there is an interconnect diagram that shows these wire numbers?

The very early version I have shows numbers around these edge of some boards, but these don't appear to tie in with the information relating to the 'wire change'.

David.
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Old 13th Nov 2017, 12:16 pm   #24
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Default Re: Philips PM5519 Service info

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Originally Posted by Vintage Engr View Post
Having just gone back to the pages of the manual that you very kindly scanned earlier, & then relating these wire changes to the board, - it's not obvious what they mean.

Presumably somewhere in the manual there is an interconnect diagram that shows these wire numbers?

The very early version I have shows numbers around these edge of some boards, but these don't appear to tie in with the information relating to the 'wire change'.

David.
There is no interconnect diagram in the service manual. I would have thought that the change is in the PCB tracks or cut track and add jumper wire....?

I would think that "387/1-395/3 added" means link between IC 387 pin 1 and IC395 pin 3 added and "connection 395/2-395/3 separated" means that link was cut/broken. The changes are surely concurrent.
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Old 13th Nov 2017, 12:20 pm   #25
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Default Re: Philips PM5519 Service info

Yes, that's the conclusion I've just come to.

I will try that & see.

David.
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Old 13th Nov 2017, 12:23 pm   #26
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Default Re: Philips PM5519 Service info

This might not be the modification or it might..

look on the bottom of the PCB and see if there is a wire link added between the negative terminal of capacitor number 531 and the positive terminal of capacitor number 534. This is shown on a sketch of the pcb in the manual, but I'm not sure if this is the fix. If you do connect these two points, just make sure that there is no significant voltage between those points before you do it.
Otherwise, if this is not it, I will have to look inside my unit.

posts crossed with above, I also see the other mods noted, so all worth a try
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Old 13th Nov 2017, 12:48 pm   #27
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Default Re: Philips PM5519 Service info

Thanks.
Have just looked into the link wires previously mentioned, not sure what they were for, but it's not an earthing fix, as the relevant pin numbers on IC 387/395 are inputs & outputs of gates etc.

Thanks Argus, for your info.

Have checked, and these two points are already linked, track-wise, and are at the same potential. I have tried a short wire link across the two points, just in case it might provide a better common grounding & eliminate sone of the noise, but sadly it didn't.

I will get there!
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Old 13th Nov 2017, 10:36 pm   #28
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Default Re: Philips PM5519 Service info

ok, I'll have a look in my unit tonight and measure the waveform noise too.
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Old 14th Nov 2017, 11:11 am   #29
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Default Re: Philips PM5519 Service info

Thanks, I really appreciate your help.
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Old 14th Nov 2017, 1:15 pm   #30
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Default Re: Philips PM5519 Service info

I have been looking at the outputs of two PM5519 generators on a 2465B scope. They appear to have only the mods in the manual.

One issue with these, examining the waveform, relates to the fact that in these generators the video output is AC coupled, unlike that seen in some more professional generators. Although they have used a decent sized coupling capacitor (2200uF) for the 75R impedance environment, there is still some signal tilt across the vertical interval.

So when the scope is locked to a waveform, to view a line, depending on where that is, the multiple traces can make the waveform appear thicker than it really is and that makes it look like noise or residual carrier. Playing around with the scope trigger, it is possible to see that the noise level , including carrier leakage (that I checked to see was properly zero'ed with R809 and R800) is just under 10 mv on the sync tip. Generator loaded into 75R of course.

Setting the output with none of the patterns selected, to just get black level and burst and chroma set at 100%, at line rate, it is possible to see digital switching transients on the black level that appear to spike up to a max of about 25mV. These are mostly not evident in a TV image.

I looked around for other mods in my unit, I found that I had added two 0.1uF monolithic ceramic caps across the power supply connections to two IC's , number 356 and 365. But unfortunately, when I did this in the 1980's I did not make a note of why, or if it was related to the signal noise issue.

I had also replaced one of those relays. The circuit tracks were fine & fragile with small pads, so on each one I fitted a miniature machined brass post and 1mm dia screw. This elevated the connections above the pcb. Then I mounted the Teledyne TO-5 relay on that (picture attached). And I obviously wasn't happy with the relay body temperature and put a TO-5 heatsink on that....imagine that a relay with a heatsink. Teledyne must have thought it was ok.

I also made a note that a 12k resistor should be paralleled with R870 otherwise, when using the external audio input to drive the inbuilt RF modulator, the audio waveform gets negative peak clipping/distortion.

Also on these units, the preset pots are not wonderful. After some years the wiper goes spontaneously O/C unless they are rotated with some cleaner.

Also, the connector to the power supply board is only just up to the job, pays to clean it and a bit of lubrication with wd40.

Hugo
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Old 14th Nov 2017, 5:06 pm   #31
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Default Re: Philips PM5519 Service info

Thanks Hugo,

I really appreciate the in-depth check of your units, and the time it must have taken.

I have just checked the output of mine on a vectorscope, and the noise is definitely noise rather than chroma leak. This was the conclusion I'd already reached, but I wanted to confirm it. I'm surprise that I'd managed to get the chroma leak that low, with the noise present, as I was only using a scope at the time, and it was difficult to see the chroma from the noise..
I have also used a TV line selector, and the noise is there on every line. All understood regarding the LF tilt, I'd also noticed that.

So it seems that your units have 50% less noise than mine, as there is a nominal 50mV on the white bar, and similar on the syncs.

Interestingly the noise is at its maximum when colour bars are selected, even with burst/chroma turned off. If the mono stairstep with frequency grating is selected, then the residual noise is far less, as it is if a white raster is selected, irrespective of whether the burst is on or off.

It may well be its coming from the bar generator section. I will continue to look!
It's a 'needle in a haystack' job, you have to be careful to use an exceedingly short ground lead on the scope, and ground it really close to the point being investigated.

Otherwise there seems to be so many earth currents carrying the noise everywhere, and you can go round in circles!

I do like your relays, very neat. My Hamlin DIP ones went in perfectly with a little bending of the legs. (theirs that is!). Kinder to the switches and semiconductors as well, as there are integral back-emf protection diodes, that the Philips relays did not have, not internal or external.

Someone else did mention that they thought there had been a Philips service bulletin regarding noise, so I live in hope of that surfacing somewhere.

It's a good job I'm retired, & not charging myself the hourly rates for the job, or I'd be bankrupt.
Still we do it for fun, - I think! My wife thiks I'm crazy.

I think I'll go back to trying to fix my new scope fault, as that would be useful on this job, which is how all this started. Its a microscope & SMD rework job, not looking forward to it,the very smal SOIC packages and it is still under warranty, but easier than sending it back to China.

Thanks again, will post again when I progress further.

David.
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Old 15th Nov 2017, 12:06 am   #32
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Default Re: Philips PM5519 Service info

David,

Try adding the 0.1uF caps that I did in my unit and see if that helps, I must have put them in for a reason and since they are on the supply rail pins to the logic IC's it must have been related to 5V rail voltage transients.

(Sorry about the ambiguous wording in my previous reply, using the word "carrier" when I was referring to the chroma signal).

In does appear that in the PM5519 they were not as diligent as they could have been keeping the digital and analog earths separate as possible to avoid this sort of thing and there is not a pcb ground plane, so like you say the results on testing depends a lot where your scope earth gets connected.
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Old 15th Nov 2017, 1:48 pm   #33
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Default Re: Philips PM5519 Service info

Thanks again Hugo,

Have tried decoupling IC's 356/365, but this has not made any improvement.
I will try adding some more caps at relevant points.

I totally agree with you in respect of the analog/ digital power rails, first principles really.

I recently tried to use a tiny encapsulated "Quiet" (according to the manufacturers) SMPS on a vintage valve guitar amplifier. I was going to use it to supply a few miliamps at 12v to the reverb driver unit, which was transistor.
This was to replace a rather hideous w/wound resistor & power zener, that was dissipating too much heat.
The spikes on the 12v rail had to be seen to be believed, and nothing would get rid of them, so I went for a miniscule 'real' transformer & linear regulator, - problem solved.

I am beginning to think I should adopt a similar approach & feed the analog parts of the PM5519 from an entirely separate supply.
Too much hassle though!

I'll let you know how I get on.

Thanks again.
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Old 15th Nov 2017, 9:22 pm   #34
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Default Re: Philips PM5519 Service info

It is interesting, the switching transients around the color bars, I'll have another look tonight and take a photo of the output from mine.

Of course partly what you see will depend on the scope's bandwidth. With the 2465B scope, running it on its 400MHz bandwidth, it always produces a less clean & less sharp looking waveform (wherever the waveform originates from) than switching on its 20MHz LPF, which makes any video waveform look cleaner regardless where it came from.

I think most likely the +/- power supplies to the analog part are ok as for the most part the amp circuits are differential design and the supply rejection is good, but it wouldn't hurt to try to add extra bypassing there.

More likely it is a common grounding issue of some of the logic and analog grounds and a common impedance there back to the supply earth.

Try adding a thick separate earth connection from the tracks in the analog area directly back to the supply's earth, bypassing the supply's connector.

Can you see any high frequency transients on the power supply outputs ?

(The caps on that supply often dry out too).

Can you also add a picture of the White waveform with the chroma switched off.

PS: I have also found many encapsulated DC/DC converters shocking for transients and noise, the "quiet" thing is mostly marketing hype. Also these spikes arise from a low Z source and are difficult to filter off without moderately big inductors and filter caps, which would have not fitted inside the small units!

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Old 16th Nov 2017, 9:45 am   #35
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Default Re: Philips PM5519 Service info

I just had a look at the waveform from my unit and compared to your photo, they are pretty well identical. I think that this is just the way these generators are, its not a fault just part of the design!
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Old 16th Nov 2017, 10:13 am   #36
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Default Re: Philips PM5519 Service info

Thanks again Hugo,

The picture I sent was, of necessity, only a screeen-shot from my in-video waveform monitor. If I had the new Hantek working, (next job) I would have sent a pic direct from that.
The in-video WFM monitor is of course bandwidth-limited. I'll try phtographing the screen off my Hitachi scope, which should show the noise more clearly. I'll set it to 20Mhz BW.
I have made some improvement by adding various capacitors across both digital & analogue supplies. They are of course though, ultimately fed from the same source.

I managed to get rid of what seems to be non-locked noise, the rest when compared to the various internally generated pulses, line up perfectly.
However there's still around 50mV pp. of it, & that really shows if one is trying to use it as a tool to line up a piece of equipment, rather than just viewing it on a monitor.

I have another pro pattern generator, & that has no readable noise at all. Even my very cheap Black Star one is clean, although its fH stability drives my vectorscope wild.

I wanted to use the Philips mainly for its circle pattern, via a standards converter for vintage TV, so I guess it won't matter too much about the noise, althogh it will then be digitized!

I'm too fussy, but I do like test gear to function correctly, otherwise one can be tracing a fault on the equipment under test, that's not really there. At one job I had, one of my tasks was to evaluate new broadcast & industrial TV equipment. When I wanted a grade A colour monitor for my workshop, the manufacturer let me go to the production line, & choose one! My reputation went before me.

I'll try & get a picture off the scope now.

David.
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Old 16th Nov 2017, 10:53 am   #37
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Default Re: Philips PM5519 Service info

Hugo,

Here's the pics off a normal scope.

Ignore the on-screen readout of the probe compensation, the cursors are set to 61mV, the Y amp was on 50mV/cm.

The second pic is for reference, and is set at 200mV/cm, to show the noise WRT the normal overall video signal.

Hopefully this will be clear enough to compare with yours.
Thanks again,

David
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Old 16th Nov 2017, 1:39 pm   #38
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Default Re: Philips PM5519 Service info

Hi,

I'm pretty sure a big part of the problem here, of the apparent thickness of the waveform, is the AC coupling of the video signal in the amplifier circuits of the unit. While it doesn't affect a test pattern seen on a screen, on a scope display the tilt causes multiple lines to be traced over each other with an amplitude offset making the waveform look thicker.

For example, see picture A below from a scope recording.

However, when I tweak the trigger level control I got it to lock onto some of the equalizing pulses in the vertical interval, and at other times a partial line, as shown in picture B, and the waveform then looks very clean.

I then tried a Hitachi V509 scope (50 Mhz bandwidth) , photo C, with video sync separators, locked to the vertical rate, then used the delay timebase to look at the individual lines, they look much cleaner.

So while its not the cleanest video waveform, it is pretty good, and a typical scope trace to some extent misrepresents it because of the AC coupling. But it probably has a few more fine switching transients on it (from the 74LS series logic IC's) than ideal.


If you look on your second photo too, you can see some faint equalizing pulses that look very clean.
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Old 17th Nov 2017, 10:40 am   #39
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Default Re: Philips PM5519 Service info

Thanks,
I guess I'm now expecting too much from the Philips.

That said, as I previously mentioned I have other TV pattern generators that , on the same scope, with BW limited to 20Mhz, are perfectly clean. I do appreciate what you are saying regarding the tilt etc. But, when displayed on the Hantek, (when it worked 3 weeks ago) which has a TV line selector, or using an old BBC line selector, the problem is still there on a white pattern (no burst), on all lines.

In the early 70's I used to work on Philips broadcast equipment, it was quite early stuff, the SPG / bar gen was made up of several separate rack-mount units, with gates & flip-flops in large IC-like modules (with discrete transistors inside!), rather like Elliot mini-logs.
Even with this, the colour bar signal was clean, so they could have done better in the PM5519. Like you say, the mixing of analogue & digital on the same power supplies isn't a good idea. I used to have a couple of PM5509's & they were cleaner than this one.

I'm going to call a temporary halt on it today, as I must get back to the Hantek scope, & either fix it or send it back to China, before the Christmas rush.

Before I do, just one further question, related to the intercarrier sound on the PM5519.

I was going to try & convert the G version back to I. Although on my unit, there is an extra PCB that encodes the Zweiton stereo sound, - on mono, it appears to be o.k. with 5.5 MHz intercarrier. I have checked it on a multi-standard TV. All I require to do, is change the intercarrier to 6MHz.
According to the very early manual copy I have, it is just two solder links that need to be altered, on unit 10, the main pcb, adjacent to the sound modulator unit.

The manual states: Close solder joint I, Open solder joint H.

There does not appear to be a solder joint I, there is however one marked J. The PCB layout that another member kindly uploaded, doesn't show solder joint 'I' either.

This might just be a typo in the manual I have. could I ask if it is the same in your manual, or is it indeed 'J'?

Thanks.
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Old 17th Nov 2017, 8:20 pm   #40
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Default Re: Philips PM5519 Service info

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Originally Posted by Vintage Engr View Post

I was going to try & convert the G version back to I. Although on my unit, there is an extra PCB that encodes the Zweiton stereo sound, - on mono, it appears to be o.k. with 5.5 MHz intercarrier. I have checked it on a multi-standard TV. All I require to do, is change the intercarrier to 6MHz.
According to the very early manual copy I have, it is just two solder links that need to be altered, on unit 10, the main pcb, adjacent to the sound modulator unit.

The manual states: Close solder joint I, Open solder joint H.

There does not appear to be a solder joint I, there is however one marked J. The PCB layout that another member kindly uploaded, doesn't show solder joint 'I' either.

This might just be a typo in the manual I have. could I ask if it is the same in your manual, or is it indeed 'J'?


I think the supplement to the service manual I have has some amendments to the links and their combinations for the various options. I'll scan it tomorrow and post here (and the relevant pages from my service manual).
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