It is currently Mon Dec 11, 2017 4:50 am

Faulty Philips PM 5508 Pattern Generator

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 11:45 am

Hi all,

I have recently received a faulty Philips PM5508 pattern generator.

Mechanically out of the 8 preset tuners (4 UHF & 4 VHF) most won't latch and several are seized solid and won't tune leaving just 1 on each bank usable, I'm hoping that it will be case of lubricating/cleaning both banks of tuners to free them off.

Trying the generator on either a 625 or 405 TV it produces test tone and nothing more than snow as a picture, it's the same on all settings with the exception of "red" which did give a very slight colour tint to the snow.

Before I start trying to repair it does anyone have any tips or pointers to the fault.

Cheers,
Marc.

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Faulty Philips PM 5508 Pattern Generator

Post by Cathovisor » Mon Oct 05, 2015 12:04 pm

Mechanically, get the tuner preset buttons moving; electrically, I think your first port of call is to Radiomuseum (as you're a member) to get the circuits. Then start looking at PSU voltages.

There's a little tip here: http://www.vintage-radio.net/forum/show ... hp?t=31577

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 12:31 pm

Cathovisor wrote:Mechanically, get the tuner preset buttons moving; electrically, I think your first port of call is to Radiomuseum (as you're a member) to get the circuits. Then start looking at PSU voltages.

There's a little tip here: http://www.vintage-radio.net/forum/show ... hp?t=31577

Hi Catho,

I've got the circuits from RM just hope I don't have to read much...I can only do English :ccg

Looking at Mikey405's post it appears to suggest replacing all of the small electrolytic caps as they are trouble. :aaq

Will check PSU voltages first though.

Marc.

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Faulty Philips PM 5508 Pattern Generator

Post by Cathovisor » Mon Oct 05, 2015 12:43 pm

marc wrote:I've got the circuits from RM just hope I don't have to read much...I can only do English

Don't worry, I can help you there if needed. I'm not fluent like young Brian, but I know enough to get my way around a manual. I had to learn a bit when I bought all those SABAs!

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 1:20 pm

Hi Marc,

I have a pdf of the manual in English for this generator if you would like a copy just let me know.
The presets on the VHF/UHF should just need a clean, some of mine suffered from not latching or not being able to adjust the tuning, until I cleaned them.
I'm sure you already know that this a 625 line generator, but I guess you were checking to see if the modulators were working with the 405 line set.
The only faults I have had with mine were the preset tuners needing cleaning, dirty pattern selector switches, and a fault transistor killing the chroma signal.

Have you tried using the video output socket for any sign of a pattern?

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Faulty Philips PM 5508 Pattern Generator

Post by Cathovisor » Mon Oct 05, 2015 1:46 pm

TVJON74 wrote:Hi Marc,

I have a pdf of the manual in English for this generator if you would like a copy just let me know.

That's what I like about this forum.... :)

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 1:57 pm

Hi Jon,

Thanks for the offer of the manual and yes please I would like a copy (PM on it's way).
I'm sure you already know that this a 625 line

Yep I know it's 625 I just wanted to see if anything was happening on VHF.
Have you tried using the video output socket for any sign of a pattern?

Thanks for the tip on "Video out" and yes we have full range of patterns.
So it looks like it's just the RF side of things and the sticky pre-sets to sort.

Marc.

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 2:50 pm

Email on its way :thumb

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 3:29 pm

TVJON74 wrote:Email on its way :thumb

Excellent Jon,
Thanks very much. :aad

Marc.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 4:18 pm

Hi all,

The story so far.....
I've managed to free the pre-sets but still can't get them all to reliably latch yet so scratching my head on this one but at least for test purposes I can get 1 to latch "just" :aaq

Electrically as already stated all patterns work fine on 'video out' but using 'RF out' I get audible tone and disturbed snow on screen which I believe is sound on vision as when tone is switched off the raster is 'still'.

Checking around for the 'known dodgy small electrolytics' I found they had already previously been changed. I have substituted the crystal as well (just because I had one to hand) but as expected no change.

So where to go next :aaq

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 4:45 pm

Does adjusting the RF output control have any effect on the raster/sound issue?

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 4:55 pm

TVJON74 wrote:Does adjusting the RF output control have any effect on the raster/sound issue?

Yes it does, tone can only be heard and raster disturbed once RF control is 1mV or over.

Marc.

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 5:19 pm

Hi Marc,
Are the dial bulb working OK? The UHF side should be lit when a UHF pre set is being used and the VHF side should be lit when a VHF pre set is being used. The +6V supply is switched between the UHF & VHF modulators and the corresponding dial bulb.
Check the +/-6V supplies are getting to the modulators.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 5:40 pm

TVJON74 wrote:Hi Marc,
Are the dial bulb working OK? The UHF side should be lit when a UHF pre set is being used and the VHF side should be lit when a VHF pre set is being used. The +6V supply is switched between the UHF & VHF modulators and the corresponding dial bulb.
Check the +/-6V supplies are getting to the modulators.

Hi Jon,
Yes the bulb and modulator supply is switching correctly between the two.
However there is only +4.2v and -5.97v at the UHF modulator
VHF modulator is +5.69v and -5.97v

Marc.

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 7:36 pm

Do you have a 625 line set you can check out the VHF output with?

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 8:43 pm

TVJON74 wrote:Do you have a 625 line set you can check out the VHF output with?

The best I can manage is my Sony 9/90 which in 405 does show a poor checker board on the VHF generator setting.
Back to UHF and either sound on picture or with tone off raster.
DSCF3425 forum.jpg
TV set to VHF 405, Generator using VHF output

DSCF3433 forum.jpg
TV set to 625, Generator using UHF output Test Tone 'On'

DSCF3434 forum.jpg
TV set to 625, Generator using UHF output Test Tone 'Off'

 
Posts: 2986
Joined: Thu Jun 28, 2012 12:20 pm
Location: The Vale Of York

Re: Faulty Philips PM 5508 Pattern Generator

Post by Katie Bush » Mon Oct 05, 2015 9:14 pm

Hi Marc,

Did you know you can make your 9-90UB display 625 lines at VHF? No tricks, no jemmies, no modifications required.. Just half press and release the system selector buttons - so that they're both 'out' (button caps level).

I just thought it would enable you to check the VHF output of the PM5508.

Conversely, as an aside, you can depress both buttons together and get 405 lines at UHF - not that there's much point in that.... :aab

Marion

 
Posts: 489
Joined: Tue Mar 24, 2015 12:01 am
Location: Wigan

Re: Faulty Philips PM 5508 Pattern Generator

Post by nuvistor » Mon Oct 05, 2015 9:22 pm

I used to use one of these, the VHF tuner will tune down to IF frequency so you put the output into the 625 IF strip by-passing the tuner. I used it as an easy test of the tuner unit before dismantling the tuner if required.
I cannot remember if it was just one button on the VHF that would do this or any.

Frank

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 9:35 pm

Katie Bush wrote:Hi Marc,

Did you know you can make your 9-90UB display 625 lines at VHF?
Marion

Thanks for that Marion, I didn't know that.
So in 625 VHF the chequer board is better but very jittery.
DSCF3435 forum.jpg
VHF 625

 
Posts: 2986
Joined: Thu Jun 28, 2012 12:20 pm
Location: The Vale Of York

Re: Faulty Philips PM 5508 Pattern Generator

Post by Katie Bush » Mon Oct 05, 2015 9:49 pm

Hi Marc,

Of course! the video is reversed (opposite polarity).. I'm pretty certain that 625 @ VHF on these sets retains the +ve going video, but the generator will be outputting -ve going video, hence the white background with black chequers! :aal

Can the tuning be refined at all, or is that as good as it gets? The signal looks noisy to me.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 9:53 pm

Katie Bush wrote:Hi Marc,
Can the tuning be refined at all, or is that as good as it gets? The signal looks noisy to me.

That's as good as it gets Marion.

Marc.

 
Posts: 2986
Joined: Thu Jun 28, 2012 12:20 pm
Location: The Vale Of York

Re: Faulty Philips PM 5508 Pattern Generator

Post by Katie Bush » Mon Oct 05, 2015 9:59 pm

What happens with say, a crosshatch pattern?

Maybe also, someone better qualified than I could advise if the negative going video from the generator would cause the apparent lack of line lock? I'm pretty certain I've seen negative images that still have perfect lock - or am I mistaken?

Marion

 
Posts: 368
Joined: Sun Aug 19, 2012 11:16 pm
Location: Salisbury

Re: Faulty Philips PM 5508 Pattern Generator

Post by TVJON74 » Mon Oct 05, 2015 10:00 pm

Does it look like anyone has been inside before Marc?
IIRC the RF output coax is very thin, none of them are broken or shorting out are they?
I can't remember how the attenuator is connected, is it possible to connect the RF output directly and bypass the attenuator?

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 10:05 pm

Katie Bush wrote:What happens with say, a crosshatch pattern?
Marion

Hi Marion,

Chequer board pattern is the only one I can get on screen the rest are just a mess of lines etc.

Marc.

 
Posts: 1553
Joined: Thu Aug 30, 2012 6:43 pm
Location: Wakefield, West Yorkshire.

Re: Faulty Philips PM 5508 Pattern Generator

Post by marc » Mon Oct 05, 2015 10:21 pm

TVJON74 wrote:Does it look like anyone has been inside before Marc?
IIRC the RF output coax is very thin, none of them are broken or shorting out are they?
I can't remember how the attenuator is connected, is it possible to connect the RF output directly and bypass the attenuator?

Hi Jon,

Yes someone has been in the generator before, the small electrolytics have been changed.
The coax's are very thin but they look in good condition though I shall verify with a meter shortly.
I have however tried the RF direct as you suggested but the results are the same which would seem to put the attenuator in the clear.

Marc.

Next

Return to Test Equipment



Who is online

Users browsing this forum: No registered users and 1 guest