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Old 9th Apr 2010, 7:41 pm   #161
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Default Re: Tv62

I think the centring magnet is the one close to the deflection coils, but it has been over 50 years since I saw an Ion trap magnet and pretty certain it is the one right close to the base with the top horizontal screw, but then it has been a long time . Chris I think you need to check voltages around V3 PCL83, not to be confused with the audio output valve also a PCL83. Check the Anode volts on pin 6 in case the frame tranny is open circuit (hopefully not). Treat the stage like an audio output i.e. THAT capacitor C16 (0.1uF) will probably need changing and maybe C15 (0.05uF) as well.
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Old 9th Apr 2010, 7:47 pm   #162
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Quote:
Originally Posted by Top Cap View Post
Hi Chris, your TV62 appears to have frame collapse
It's a nice bright frame collapse though which is probably good news for the tube.

Is the tube aluminised? Would that make any difference to the need for a bent gun to throw the ions off course, I.e would such a tube not need a trap?

Dave
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Old 9th Apr 2010, 7:49 pm   #163
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The Tv62 uses an ion trap tube. Electrostatic focus models use a AW36-20 [aluminized] or 21 and the magnetic models a MW36-24 or 44. [21/24/44 non aluminized, all ion trap] You have something on the screen so leave the ion trap alone for the moment. All Mullard rectangular CRT's use an ion trap.
As others have said you have what is known as a frame collapse. Must admit I'm suspicious of what you might have accidently done. It's unusual to have a complete collapse, heavily distorted yes but not total. No problems, we will sort it.
Are the scanning coils correctly connected? They are plug in pins. The collapse appears to be modulated and rather strange. If you are certain everything is in order we can feed an output into the frame output valve control grid and see if it opens up. Check all your connections and wiring first. Don't despair. Looks a brilliant tube to me! J.
PS I have a working TV63 in the workshop so if you require a loan of the units for test you are welcome but that is a long way down the line. You will only need any old test meter, a few odd capacitors and those croc clips I sent you to solve this. Just think DAC90 but don't polish the knobs!

Last edited by Heatercathodeshort; 9th Apr 2010 at 7:56 pm. Reason: P.S. added.
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Old 9th Apr 2010, 7:50 pm   #164
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Default Re: Tv62

working upside down I was measuring the wrong valve. here we go again hang on

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Old 9th Apr 2010, 8:01 pm   #165
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Default Re: Tv62

pin1 94
pin2 5.4 whistle stop when probe attached
pin3 2.6
pin 4&5 5
pin6 91
pin7 -
pin8 2.6
pin9 4.7

all the little pin connections were checked and double checked and checked again 4 wires, red to paxolin board with pot, big fat yellow to LOPT, green and blue to what looks like a TX. Photo'd and notes followed
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Old 9th Apr 2010, 8:14 pm   #166
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To follow on. Ensure you are happy with all the connections and any components you may have replaced/disturbed including the scan coils. The ECC82 heater wiring is correct. The heater is centre tapped for series or parallel connection in this case pins 4 and 5 are joined together and the centre tap is taken to pin 9. [.3amp operation]
There should be reasonable H.T. on pins 6 and 8 of the frame output valve,
the pentode section of the PCL83 [V17]. To check the output stage clip a capacitor around .01uf, exact value not important from the heater line, pick this up from either pin 4 or 5 of the PCL83 and connect the other end to the control grid pin 9, switch on. This will feed a 50c/s input from the heater line and the collapse should open up into a distorted mess. If this happens the output stage is operational i.e. the scan coils, connections, output transformer and supplies are in order. We can then work back to the oscillator and check a few things in that area. Once you have some form of raster it will become a doddle..Honest! John.

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Old 9th Apr 2010, 8:33 pm   #167
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Default Re: Tv62

John,

As advised it does as you say

Chris
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Old 9th Apr 2010, 9:03 pm   #168
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Default Re: Tv62

well done that man, now you've got the screen talking to you.

Jay
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Old 9th Apr 2010, 9:05 pm   #169
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Try checking the continuity of the height control. You are so close.
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Old 9th Apr 2010, 9:30 pm   #170
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More good news. Just looking at the circuit and there is no blocking transformer for you to worry about Chris.
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Old 9th Apr 2010, 9:34 pm   #171
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Ha! Ha! A few quick checks. Check the voltage on pin 1 of the PCL83 the triode section. It should read around 65-115v.
This is derived from the boost rail via R68, a 100k resistor and R100 a 1m that may well be O/C or very high resistance. This is decoupled via C39, a 2uf electrolytic that may be S/C. As PJL suggests the height control may be O/C or the frame hold may be suffering the same problem. One step at a time. J.

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Old 9th Apr 2010, 9:45 pm   #172
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Default Re: Tv62

John
started at 10v now dropping to 9.7v on pin1 looks to continue to drop 8.9v now 7.3v now bottomed out at 4v

R68 R100 are they from the Bush document? or Trader? as the Trader does not look like my chassis but the Bush document does

TOPCAP
168v on pin 6 and the speaker buzzs and screen flickers and brightens when probe touched then settles back.

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Old 9th Apr 2010, 10:04 pm   #173
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Check R19...the 1M?
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Old 9th Apr 2010, 10:18 pm   #174
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Default Re: Tv62

R19 seems weird when i connect the meter it starts at meg range reading 2.1M dropping rapidly to 1.9M then switches into K range and sits at 891k

just cleaned resistor wires and clipped again now reading 934k and i'm watching it slowly climb its now at 944k

now at 960k and slowly rising
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Old 9th Apr 2010, 10:28 pm   #175
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John has already given you the likely suspects - I'm just interferring! Try measuring the voltage at the other end of the 1M first.
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Old 9th Apr 2010, 10:31 pm   #176
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The set is switched off and I was doing an OHMs test, its still rising now at 992K. I will power on and do a voltage check.
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Old 9th Apr 2010, 10:35 pm   #177
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400v one side 4.8v the other

regarding Johns suspects, I will have to try and figure r68 and r100 and what they relate to on the Bush sheet

Johns C39 (Trader) 2uF is C14 so R100 is R19 (pjl Oops I see) so he's referencing Trader so It looks like R68 on trader is R37 on mine

R37 (100k) read 108k so that's with tol
R19 (1M) is just plain weird

John, can we work from the bush as discussed at the start of this thread the Trader sheets do not match the same layout as my chassis mine is a single tag board not the dual. Jeffrey had this problem too.

Last edited by oldticktock; 9th Apr 2010 at 10:50 pm.
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Old 9th Apr 2010, 10:40 pm   #178
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Default Re: Tv62

Well swop it then if you think it's knackered.

Cheers,

Steve P.
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Old 9th Apr 2010, 10:49 pm   #179
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The boost voltage is present. John could get you there in one step but with me it takes longer! My only concern is the AC volts might be causing a false reading.

Switch off and measure the resistance from pin 1 to chassis. I guess you have replaced C15.

...and resistance of pin 2 to chassis.

Last edited by PJL; 9th Apr 2010 at 10:57 pm.
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Old 9th Apr 2010, 10:59 pm   #180
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Default Re: Tv62

my meter seemed to have got itself notted. Its now reading ok and the 1M is 4.4M!!!!!!!!!!!!!! that won't help. Going to replace

No not replaced any caps for fear of the Johns wrath, all I did was the electrolytic smooters C31 & C38 as these were all in a state of collapse

Last edited by oldticktock; 9th Apr 2010 at 11:26 pm.
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