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Old 4th May 2010, 7:05 pm   #201
PJL
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Default Re: Pye v4

I think we should continue working backwards and focus on the frame collapse. The RF can wait so just disconnect R131 and start on the frame oscillator.
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Old 4th May 2010, 7:28 pm   #202
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Default Re: Pye v4

Guess I have to check the frame oscillator/output stages

can I try the frame output valve check I did on the TV62, by clipping in a capacitor of 0.01uf from the heater line and connect the other end to the control grid? that changed the line and the collapse opened up into mess but a good mess.

Chris
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Old 4th May 2010, 7:31 pm   #203
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Default Re: Pye v4

Is there any indication of audio Chris (buzz/hum/squeak)? If I'm right one HT rail feeds the frame and audio stages. That might narrow the frame collapse down a little bit.

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Old 4th May 2010, 7:36 pm   #204
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Default Re: Pye v4

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can I try the frame output valve check I did on the TV62...
Can't see any reason not to try. Also measure the DC voltages around the vertical osc/output and see how they compare to the data. Be aware that the impedances at the grids are quite high so the voltages you measure with your DVM will differ from those quoted. Don't forget to check the HT supply to the stage - it won't work at all if that's missing or way low.

An easy cold check is the continuity of the field scan coils and both windings of the output transformer. You can check the oscillator transformer too.

There's a high chance that the cathode resistor and its decoupling electrolytic will need to be changed. You can measure the resistor with the power off. likewise any resistors over 100K will likely have gone high and all the paper caps will need to be changed at some point.

PS: Cross posted with Dave - great minds think alike on the subject of HT.
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Old 4th May 2010, 7:40 pm   #205
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Default Re: Pye v4

Dave no humm but when volume control is turned it makes a rustling sound

As I was saying to Malc today the Newnes book schematics are so much better for a newby like me as they label each part of the circuit so its easier to concentrate on the components in the part of the circuit. The trader I'm working from is harder and I'm having trouble working out the frame output valve, my uneducated brain believes it to be one of the ECL80's

Thank you Jeffrey, some good tests to get on with.
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Old 4th May 2010, 7:53 pm   #206
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Default Re: Pye v4

I'm working from the Pye V2 data which happens to be at hand. This should be pretty similar to the V4 but I don't want to be too dogmatic. I can dig out the Trader and RTVS data if required. The FOP is an ECL80 and readily recognised because there's a transformer connected to the anode of the pentode and the secondary of said transformer is conencted to the V scan coils. Just like an audio output stage really.
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Old 4th May 2010, 8:04 pm   #207
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Default Re: Pye v4

Just follow the path back from the coils and you will find V18. There are alot of caps but C92 and C96 are both coupling caps and C94 is critical too so start there.
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Old 4th May 2010, 8:41 pm   #208
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Default Re: Pye v4

Changed C92, powered on no change to Frame collapse

Changed C96, powered on Frame now expanded.

I will now change C94 this is wired in parallel with C96

See pic
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Old 4th May 2010, 8:47 pm   #209
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C94 is not in parallel! It's the capacitor that is charged up to form the sweep.
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Old 4th May 2010, 8:48 pm   #210
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Sorry my ramblings again was just about to edit and you caught me
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Old 4th May 2010, 8:50 pm   #211
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Default Re: Pye v4

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I will now change C94 this is wired in parallel with C96

See pic
Not on the Trader sheet it isn't. Only one end of each cap' is joined together

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Old 4th May 2010, 8:58 pm   #212
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Default Re: Pye v4

As it's looking like the frame oscillator is going to work and you have done the coupling caps, I would focus on the other bits that could cause damage and go back to the line oscillator and change the remaining caps. I would also do the audio coupling cap C84 again to prevent any damage.

All those caps are going to keep you busy for a few hours!

PS: the waxies in the range C39-C51 and throw in C36 as it's a coupling cap to the sync seperator.

Last edited by PJL; 4th May 2010 at 9:11 pm.
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Old 4th May 2010, 9:16 pm   #213
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Default Re: Pye v4

David,

I think when I start to get tired I babble, I have been know to dribble as well, it's an age thing I have even been known to do both at the same time.

Now Changed C94 and while I was in under that section C93.

Frame is more expanded now.

PJL,
sound advice which shall be followed, I think as I'm getting tired and this is my 5th day at this I shall rest up and pick up the iron tomorrow.

This day has been a good day, steps in the right direction after what looked like game over.The jaws of defeat have been avoided but I'm still not home and dry i feel this set has more lessons to teach me.

Also that R131 issue still bugging me, which no doubt I shall end up dreaming about tonight.


Chris
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Old 4th May 2010, 9:37 pm   #214
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Default Re: Pye v4

Aahh things really beginning to happen now! Well done!


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Old 4th May 2010, 9:55 pm   #215
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Default Re: Pye v4

This all looks most encouraging. You are now pretty certain that all the transformers are OK and the timebases will work. The RF/IF side may still have some horrors but they are not showstoppers except perhaps for mechanical damage to IFTs.

The only real worry is now is the CRT which may only have had a temporary cure.
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Old 4th May 2010, 10:32 pm   #216
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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!
Something for later, but I think that was C18 and will be responsible for your R131 problem...

You seem to have mastered the delicate skills of tube tapping...really good result.
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Old 4th May 2010, 10:44 pm   #217
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Default Re: Pye v4

Changed the Dali cap (C18) and R131 and its a 5watt affair, still decided to smoke see pic in #200, as you say I've left this little treat for later, It will be haunting me tonight though.
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Old 4th May 2010, 11:45 pm   #218
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Default Re: Pye v4

Chris

You're on a very steep learning curve with the sets you've tackled so far but are getting excellent results. After this the TV22 will be a doddle.

Keep up the good work

Keith
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Old 5th May 2010, 2:01 am   #219
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Default Re: Pye v4

I've been following this thread from day one and its been a roller coaster ride just reading it I think you're brave tackling something like this, keep up the good work...
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Old 5th May 2010, 12:13 pm   #220
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Default Re: Pye v4

An update for this morning, started to work my way one by one and observe the results.

Caps changes so far today

C36
C39
C84 this was interesting, it states .01 on the trader but .005 was in circuit!!! I replaced it with the correct trader value.

Results so far.

Chris
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