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Old 14th Jul 2010, 1:15 pm   #41
FERNSEH
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Default Re: GEC BT1156 First Light & Vidor CN4216

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GEC Z77 = Mazda 6D2, also EB91 and 6AL5.
Mea culpa. It should be GEC D77 = Mazda 6D2, also EB91 and 6AL5.

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Old 14th Jul 2010, 1:16 pm   #42
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Default Re: GEC BT1156 First Light & Vidor CN4216

Hi Just found a valve which had xxP19 "xx" was rubbed out it looked the same as the 30P19 so I put it in.

Power up
30 seconds in, line whistle a further 40-50 seconds and raster ( a lot quicker) although it was missing by 2 inches from top and bottom it was brighter and the brightness control could be used without it loosing the picture. With the old 30P19 in it would take longer to provide the raster but it was larger but duller. Also the line speed could be adjusted to run slower along with the hold you could just get a nasty Testcard before the setting would drive the tube to fade out.

The original 30P19 has 21 under the BVA whereas the pull I had states 2x under the BVA
does this figure mean anything?

chris

Last edited by oldticktock; 14th Jul 2010 at 1:25 pm.
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Old 14th Jul 2010, 1:22 pm   #43
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Default Re: GEC BT1156 First Light & Vidor CN4216

Thanks David & Peter, pleanty of things to check and I believe Teleman also stated some of those too (great minds).

I noticed from the circuit Boost should be around 520V on T3 pin1 and HT should be 205V. I had Boost at about 380V and HT at about 187V. A1 was 298V and A2 7KV.

Thanks to all for the constructive advice, I think I need to now go away, consolidate the advice and get my head down.

Chris
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Old 14th Jul 2010, 1:30 pm   #44
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Default Re: GEC BT1156 First Light & Vidor CN4216

Annyeonghaseyo? Cris,
You mention that you have lost picture height after replacing the 30P19. Almost certain that the other 30P19 had low emmision.
The reason for the reduced height is that the EHT voltage has increased. This is good news. Check the A1 volts at the CRT base, pin 10. Should be about 450 volts.

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Old 14th Jul 2010, 1:40 pm   #45
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Default Re: GEC BT1156 First Light & Vidor CN4216

Correct just put the other one back in measured EHT and it's 8.5KV now, wow i learned something there.

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Old 14th Jul 2010, 1:45 pm   #46
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Default Re: GEC BT1156 First Light & Vidor CN4216

First pic is with the line hold at what i think is normal speed, the second picture is when I reduce it I can lock a bad testcard.

EHT now at 9.2KV
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Old 14th Jul 2010, 1:48 pm   #47
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Default Re: GEC BT1156 First Light & Vidor CN4216

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Correct just put the othe rone back in measured EHT and it's 8.5KV now, wow i learned something there.
Hi Cris,
Still could do some more KVs. Service manual says 13KV.

These little sets can show a brilliant picture.

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Old 14th Jul 2010, 2:02 pm   #48
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Default Re: GEC BT1156 First Light & Vidor CN4216

Yup not wrong there, I will check all the components suggested by your goodself and Teleman, should keep me out of mischief.

I will also try and test the pull 30P19 I just installed, see what my AVT makes of it, although it's given an improvement It may still be a duffer, I can compare it with the original.

Chris
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Old 14th Jul 2010, 2:20 pm   #49
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Default Re: GEC BT1156 First Light & Vidor CN4216

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Check the A1 volts at the CRT base, pin 10. Should be about 450 volts.

DFWB.
Ooops forgot to say A1 is 286V errr way off
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Old 14th Jul 2010, 5:50 pm   #50
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Default Re: GEC BT1156 First Light & Vidor CN4216

Valves ready to collect
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Old 14th Jul 2010, 6:12 pm   #51
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Default Re: GEC BT1156 First Light & Vidor CN4216

Annyeonghaseyo? Cris,
looking at the picture CIMG2507 I notice that the line timebase frequency running too high. You must get the timebase going at the correct speed, that is, 10,125 cycles per second.
Have you got access to an oscilloscope? The 405 line pulses should be 100micro seconds apart. When the line timebase frequency is too high, the EHT voltage reduces.

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Old 14th Jul 2010, 6:20 pm   #52
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Default Re: GEC BT1156 First Light & Vidor CN4216

goedenavond, David

I have an oscilloscope but it's of no use to man or beast, it's going to be taken off then bench and moved to the forgotton corner of the loft. I have been trying to set it by how the other working sets sounded.


ahh in the first pic I thought it was running at the correct speed, the second I knew was wrong but thought I had slowed, it up so that I could get the bad testcard.

I thought the higher the pitch of the tone the faster the TMB was running, the low the pitch the slower the TMB was running?

Chris

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Old 14th Jul 2010, 6:24 pm   #53
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Default Re: GEC BT1156 First Light & Vidor CN4216

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Valves ready to collect
Cheers Malc,

I will call tomorrow, if that's alright.

Chris
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Old 14th Jul 2010, 6:31 pm   #54
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Default Re: GEC BT1156 First Light & Vidor CN4216

Dia dhuit Chris!.
Another way of checking the line speed is with a frequency counter, assuming you have one.
Your idea of beating the sound of the oscillators should work too but if you have tinnitus it may not work. The other way is to download an oscillator program to your PC then select 10,125HZ or cycles per second as David says!
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Old 14th Jul 2010, 6:35 pm   #55
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Default Re: GEC BT1156 First Light & Vidor CN4216

Guten Abend, Cris,
The valve V14 (Z329/30F5) is the most likely cause of the line time frquency running too high. An EF80 or 6F23 will work fine in that position. Is there a great change in frequency when the line hold control is rotated?

Was your last greeting Dutch or Afrikaans?
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Old 14th Jul 2010, 6:48 pm   #56
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Default Re: GEC BT1156 First Light & Vidor CN4216

Trevor, David Olet niin hullu televisio insinöörit.

Yes there is a noticeable range when the line hold is rotated, I can hear it from quite low to quite high and all in between. I will try moving one of the other Z329's into that position or an EF80, perhaps that's why there is a few EF's already in the set.

keep looking for a freq counter just missed on recently.

It was Dutch

Chris
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Old 14th Jul 2010, 7:11 pm   #57
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Default Re: GEC BT1156 First Light & Vidor CN4216

Ok forgot about trying to fudge the controls to get the testcard.

Set the line hold to what I think sounds correct, the A1 is now at 312V and the EHT is around 9.6KV

If you imagine the line hold as a clock starting at 1 and ending at 9 that's it's travel.

at 1 its the lowest freq, i get a testcard about four of the across the screen. At about 3 it gets another testcard i've got it set at about 8.

If I set line hol to max freq i get 9.4KV, if I set the line hold to lowest freq i get 10KV.

Subbed V14 no change
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Last edited by oldticktock; 14th Jul 2010 at 7:29 pm.
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Old 14th Jul 2010, 8:19 pm   #58
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Default Re: GEC BT1156 First Light & Vidor CN4216

I'm a bit concerned with previous work that has been carried out I need to look into this area closely i think. R131 reads 2.7M one end of r131 goes up to the stuffed ex waxy which I think is the boost cap, was it meant to be here?
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Old 14th Jul 2010, 8:30 pm   #59
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Default Re: GEC BT1156 First Light & Vidor CN4216

Leave that, there's nothing there that can upset line speed.

If the valve is OK, check the resistors and variable resistor around it and any capacitors. Only on the line oscillator stage. Get the speed right and take it from there.

Cheers,

Steve P.
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Old 14th Jul 2010, 9:16 pm   #60
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Default Re: GEC BT1156 First Light & Vidor CN4216

I'm a duffer the big stuffed waxy is the A1 supply decoupler durr!. Still investigating

hvorfor er jeg så dum
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