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Old 1st May 2010, 11:36 pm   #61
oldticktock
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Default Re: Pye v4

The trader sheet shows C106 being located between V15 & V5 and its value being 0.003. quite odd for a Boost cap and I don't believe it is, there is a mix-up between the two sets of service data.

I think the PYE service data and the trader sheet are at odds with each other as the Trader clearly states that C57 is used to boost the HT to V10 (PL81) to CRT 1st anode and to V2b anode. Sections a and b of T2 form an auto-transformer to step up the line fly-back voltage which is then rectified by V11 (EY51) and suppled as EHT to CRT 2nd anode.

So I believe I have already changed the Boost cap.

looking at my chassis c106 (0.003) is amongst the EF80's and not the same as your PYE service sheet, I had this same issue with the Bush TV62 service sheet and Trader sheet at odds with each other.

Chris

P.s.

Photo 1 shows the screened box opened up this is where the PYE service data say C106 should be, clearly you can see that it is not.

Photo 2 shows the full chassis view and the 3 caps to the top left, the middle one being C57, boost cap.

Photo 3 another angle of the EF80 screened box

Photo 4 shows 2 caps changed up top and the new EY51

Anyone have an idea about the fizzing blue haze around the PL81, is it because the topcap resistor is not insulated like the PY81.

First job tomorrow is to rotate the scan coil unit and then continue, for now my head needs bed
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Old 1st May 2010, 11:40 pm   #62
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Default Re: Pye v4

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Originally Posted by oldticktock View Post
Lloyd I think that's a distinct possibility.

just checked and well spotted Lloyd the scan coil housing is 90 degrees to the right of where it should be need to rotate and that would mean frame collaspe. I'm such a twonk.

No you're not a twonk!!

We've all done things like that in the past particularly with replacement coils. Also remember if you wire the frame coils in reverse, you get an upside-down picture. If you wire the line coils in reverse you get a back-to-front (mirror image) picture. If you get both sets of coils in reverse you get upside down and back-to-front.

However if you wire the frame coils up as line then the set usually won't work because the impedance of the coils is much too low and damps the line stage.

It's all part of the learning curve.

Once you have a picture, you'll probably have to adjust the ion trap for brightest picture.

Rich.
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Old 2nd May 2010, 8:39 am   #63
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Default Re: Pye v4

Refitted the scan coils, they were aligned incorrectly.

Now I have a 10cm band in the middle of the screen with wiggles in the top half and the bottom 5mm is a brighter white line. The brightness is still too low to take a photo.

Still getting the fizzing and blue glow around the PL81, tried insulating the TC resistor/wire with some heatshrink, no change.

I guess theres a few more caps which are causing this and I just need to figure out which ones, I think it's similar to the problems I had with the TV62, so will go and try to remember what to do.

Power on, wait for line whistle and on screen band on CRT, take measurement
pin2 145V
pin10 220V

will take readings in 5 mins

Update Now :-

pin2 145V
pin10 201V

screen still display the large band as described above, fizzing seems to have stopped around the PL81 but it still has a faint blue glow around its waist. This was the same when a new one was fitted this only mifested itself late lastnight.

Last edited by oldticktock; 2nd May 2010 at 9:03 am.
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Old 2nd May 2010, 9:02 am   #64
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Default Re: Pye v4

Chris. What voltages can you measure around the PL81? Just measure voltages around the base...don't put your meter on the top-cap!!

I wouldn't run it for too long if the PL is under stress. It would be worth looking at the valve socket itself. You do have some sort of line drive or the anode would be getting red hot but it may not be enough.


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Old 2nd May 2010, 9:55 am   #65
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Default Re: Pye v4

I recently took the tube out of a set and when I put it back together had frame collapse.

What I had done was to pull a wire from the coils when seperating the coils from the insulator which goes between them and the tube. They were ruined:

I understand it is a very common mistake to make. I now soak them in WD40 before removal to soften the wax.

Dave
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Old 2nd May 2010, 10:46 am   #66
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Default Re: Pye v4

I honestly don't think that's the case for me, I never disturbed the coils just gently withdrew the metal housing they reside in. The case is on long silicon wires see photo of coil unit when it was removed the were neatly tucked in side, the scan coils were never removed from the casing.

I'm optomistic its a Hunts somewhere in the circuit. I kid you not but Salvador Dali has been at one cap It's a small 1cm brown Hunts and it looks like the famous melting clock, if I can take a photo I will, most bizzare never seen that!

Just finished SWMBO chore and mowed the lawns, now it's back to proper work.

Chris
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Old 2nd May 2010, 11:16 am   #67
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Default Re: Pye v4

PL81 readings

pin1 6.3v
pin2 wildly fluctuating mV
pin3 6.5mV
pin6 6.5V
pin7 130V
pin8 129V
pin9 6.6V

Pin 8 has a 3.3K res on this side of it measures 129v, on the other end which hits pin9 of PY81 its 198V

So The screen is 40V shy of the expected 170V or should it be 200V

Last edited by oldticktock; 2nd May 2010 at 11:26 am.
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Old 2nd May 2010, 1:18 pm   #68
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Default Re: Pye v4

Pin 2 is g1. You should have a solid negative reading here of tens of Volts. You might be measuring it wrong if it all over the place as the LTB wouldn't work if it was. Make sure your meter is on DC Volts

Dave
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Old 2nd May 2010, 1:45 pm   #69
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Default Re: Pye v4

Hi another issue I found was I think R131, it is connected to one end of the big smoothing can the other leg going to the tag board below, this had broken off.

R131 is listed as 470 OHM, all I had to hand was a 470 1.5W. Soldered it in and it smoked, then lit up like a bright ember, switched off straight away guess the wattage is incorrect.

The old one was a rough grey wire wound but as it had fallen apart I could not tell what wattage it was. Pictures of the old and the new which I shall remove as it's clearly not man enough.

found my tin of high wattage resistors, I will parallel wire a 220&250 5W
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Old 2nd May 2010, 2:12 pm   #70
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Default Re: Pye v4

Quote:
Originally Posted by oldticktock View Post
I will parallel wire a 220&250 5W
You'll be in trouble if you do. It is in SERIES that you need to connect them to get 470 Ohm

Dave
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Old 2nd May 2010, 2:38 pm   #71
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Default Re: Pye v4

Can you post the section of the circuit, PSU, CRT, LOPT and line oscillator? I wouldn't start replacing failed resistors with higher wattage types as there is likely to be an underlying fault.
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Old 2nd May 2010, 2:40 pm   #72
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Default Re: Pye v4

Yep, I meant series must learn to repair the sync pulse between my head and my mouth I have a calculator which does it all for you anyway which makes life simple.

Serious issues going on here wired in the 220R&250R 5Watt=470R 5 Watt and that smoked for England too, must be the fault which overloaded the previous.

I wonder what causing that, I measured the two tags on the smoother before I discovered the broken resistor leg (measuring led me to noctice the break) and the were at or just over 200V

I will unsolder the leg that will recreat the scene as it was before I found it and come back to that, pretty worrying though.

p.s. don't be fooled by the photo, the bottom of the resistor chain does not go to that coil, its just the photo angle.

edit:- second photo added, new angle and schematic as requested by PJL
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Old 2nd May 2010, 3:26 pm   #73
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Default Re: Pye v4

Quote:
Originally Posted by Boom View Post
Pin 2 is g1. You should have a solid negative reading here of tens of Volts. You might be measuring it wrong if it all over the place as the LTB wouldn't work if it was. Make sure your meter is on DC Volts
Dave
Some DVMs won't give a sensible DC reading on the sort of pulsed AC you find here. Unless and until you know the behaviour of your DVM a conventional analogue meter is often better for this sort of measurement.

PS: When you give us a set of voltage measurements on valve pins it would be more helpful if you looked up the data and told us which electrodes you were measuring. It would save most of us going to the valve data books to find out which electrode was on pin x of a PLxx.
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Old 2nd May 2010, 3:40 pm   #74
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Default Re: Pye v4

R131 is the HT feed for the RF by the looks of things? If it burnt up at the rate you suggested you may be looking at a dead short. You can track this down later, just remove R131.

You say you have a line? does it fill the whole width of the screen?

Cathode Pin 3 and g3 Pin 9 of the PL81 are connected but you have very different voltages. Can you check which is right and give me the value of R70 so we can calculate the average current.
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Old 2nd May 2010, 3:51 pm   #75
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Default Re: Pye v4

Line fills entire width

R70=47R

pin3 (k) 6.7V
pin9 (g3) 6.7V

Last edited by oldticktock; 2nd May 2010 at 4:06 pm.
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Old 2nd May 2010, 4:24 pm   #76
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Default Re: Pye v4

This is all taking a step backwards, line whistle stopped looked at screen line gone, EY51 not lit now, EHT gone!!

This set is annoying me now
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Old 2nd May 2010, 4:31 pm   #77
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Default Re: Pye v4

142mA but there is a link on the circuit going off somewhere? Any voltage references in the service data? Have you tried changing V12?

Think you may have to wait for some expert advice.
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Old 2nd May 2010, 4:42 pm   #78
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Default Re: Pye v4

Replaced PL81 no EHT, replaced the PY81 EHT restored, but that fizzing and cracklin sound around those two returns as well, I'm not going to fry another set so that's it for now. I found that by touching the probe on PL81 pin8(g2) I can effect the fizzing/cracklin this is also true of pin9(a) of the PY81

PL81 Pin8(g2) has a 3.3K res linking to pin9(a) of PY81

Also that blue glow I saw on the PL81 I thought it was around the outside, It must have been on the inside, there is s dark patch etched to the side of the bulb (see pic)

this is going to be dragged screaming into operation, I think John W was right when he said this could run into 120 pages

shame as I thought I was making progress yesterday by getting the line and a 10cm band of noise today seems to have been a day of regression.
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Old 2nd May 2010, 5:55 pm   #79
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Default Re: Pye v4

Hi Cris,
The first attachment shows the line timebase circuit and the other the frame timebase.

The coupling capacitor C98 must changed, that's the one connected to pins 6 and 7 of the line oscillator V26B. The negative volts at the control grid of the PL81 should be in the order of -50 or more. The line drive waveform should be greater than 100 volts P-P.
C106 is the boost capacitor.

Is the line oscillator running at the correct frequency? 10Kc/s.

DFWB.
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Old 2nd May 2010, 6:09 pm   #80
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Default Re: Pye v4

That unusual looking PL81 is a Mazda France 21B6 which was marketed in the UK as a PL81. The 21B6 was a very robust valve and was often fitted into sets where there was a problem with the original PL81.

The fact is it was fitted to mask some on going fault.

DFWB.
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