3rd May 2010, 5:57 pm | #161 |
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Re: Pye v4
Yep that's a bog standard .3A heater. Its sounds cream crackered.
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3rd May 2010, 6:00 pm | #162 |
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Re: Pye v4
Used my little ole AVO Minor and the CRT heater measures 1.2V
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3rd May 2010, 6:04 pm | #163 |
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Re: Pye v4
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3rd May 2010, 6:11 pm | #164 |
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Re: Pye v4
closest thing I've got is an MW36-20 in my tv62, and the heater measures 3.7 ohms on my dmm. if its lit, then it has to be doing something!
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3rd May 2010, 6:16 pm | #165 |
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Re: Pye v4
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3rd May 2010, 6:41 pm | #166 |
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Re: Pye v4
No it isn't. It's about 4.75 inches. 12/2.54 or look at a dual scale ruler.
2 foot 6 inches is 76.2 cms, so I don't know how you arrived at that figure.
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3rd May 2010, 6:45 pm | #167 |
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Re: Pye v4
With nothing to lose why not put a bench psu across the heaters set to 6V? You never know it might just blow the shorted part clear.
Dave |
3rd May 2010, 6:46 pm | #168 |
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Re: Pye v4
Graham,
As my Post isn't there I'll have to own up I couldn't find it to edit it anyway. Garbage In, Garbage Out as they say. Alan |
3rd May 2010, 6:50 pm | #169 | |
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Re: Pye v4
Quote:
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3rd May 2010, 7:11 pm | #170 |
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Re: Pye v4
Shame, as I think we were well on the way to a new record for the longest thread with a successful outcome. The set still has a problem with brilliance control, frame collapse and a short in the RF HT somewhere.
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3rd May 2010, 7:46 pm | #171 |
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Re: Pye v4
This is a shame. Chris, try the old trick of tilting the set back, and with the set powered up and your meter set on AC Volts to the tube- pins 1 and 12 - gently tap the neck of the tube with an insulated screwdriver handle.
Hopefully, you might then see the heater voltage rise as the short clears. This is usually only a temporary cure though, but it might give you some screen illumination. Good luck. SimonT.
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4th May 2010, 9:58 am | #172 |
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Re: Pye v4
Hi Chris,
there's one more thing that has occurred to me. The heater chain is decoupled by several capacitors along its way, any of which could cause low heater voltage in some parts with higher voltage in other parts. Any of these capacitors (if faulty) would cause the line oscillator heater to be underun as well as the tube heater, so you'd expect to see symptoms elsewhere... (you did have frame collapse didn't you?)... Before giving up it might be worth checking the voltage across the heaters of, say, V9 or V17, V8 etc.. If they are also down below the correct voltage then a quick snip here and there should bring them back up and prove the point. They would need to be replaced to get the RF section working properly but aren't needed just to get a raster. Pete |
4th May 2010, 10:08 am | #173 |
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Re: Pye v4
Hi Pete,
Thanks for the advice I will have a look, although with a CRT heater resistance of 1.2R I was advised that this was the game over point. Must admit this depressed the hell out me, I was enjoying the challenge and this poor ole Pye has had more than it's fair share of bad luck. Chris |
4th May 2010, 11:02 am | #174 |
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Re: Pye v4
I keep going back in my mind about R131. One leg end had broken away, when I replaced it with ceramic not wirewound it lit up like a xmas tree, so I left the leg disconnected. I then fitted a series 220R&250R 5 watt and this made the EHT go, so the one leg was disconnected again. It seems to be the + feed from C101 which goes to the bottom leg of R131 and the top leg is fed from + feed from C102 and links to L36 which inturn via C56 ends up in the CRT Grid?
After all this the faffing the on screen line went and never came back. This must be an issue for the CRT too, is it all related. |
4th May 2010, 11:37 am | #175 |
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Re: Pye v4
I think as you said Chris with the tube heaters at 1.2 Ohm it is game set and match for the CRT. Are you going to NVCF? There might be a scrap set there to pinch a tube from so I wouldn't totally give up just yet.
Dave |
4th May 2010, 11:42 am | #176 |
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Re: Pye v4
Hi Dave,
Thought so, no not going to the NVCF as I don't like driving at the best of times and that distance is too much. I have asked in the wanted ad section if anyone spots one to think of me and I would cover all costs and some extra for their trouble but I know that's asking a lot. I will just leave the PYE as a display or if I need organ donations. Chris |
4th May 2010, 11:44 am | #177 |
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Re: Pye v4
Hi
Chris sorry to hear about your heater CRT props of yesterday afternoon! But just looking at the Trader I see R131 is conected to C101 as you say! This cap C101 has not gone O/C has it? And hence why you resisitor lit up! As just having a quick look this is the HT feed line for Valves 1 to 5 maybe worth checking C101. And other caps etc in this line Just a thought and maybe I'm miles out here again. Kevin. Last edited by Kevin19; 4th May 2010 at 11:54 am. |
4th May 2010, 11:44 am | #178 |
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Re: Pye v4
Regarding R131. This carries HT current to the RF stages. It would appear there is a short circuit somewhere on this HT rail, resulting in excess current which is burning out the resistor. Being that bad an ommeter test should find the fault.
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4th May 2010, 1:34 pm | #179 |
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Re: Pye v4
I have just got a bench power supply thanks to Malc (nice chap, that's two treats in 4 days, seeing other peoples collections) and have set it to 6.5V and connected it to the CRT pin 1&12 a nice healthy glow ensued, measured with a meter and its 6.5V
This surely must mean the CRT is fine it's just some other issue in the PYE? Chris |
4th May 2010, 1:38 pm | #180 |
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Re: Pye v4
If the CRT heater is glowing rather too brightly it means there's a partial short in the heater.
You have nothing to lose by running up the set with the CRT heater on the bench PSU. Just take the leads off pins 1 and 12 of the base and short them to maintain heater chain continuity. PS: After seeing Lloyd's post that's a much better way than simply looking at the glow. |