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Philips K80  

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acj1980
(@acj1980)
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For a couple a weeks ago i got this K80 from a friend, the condition is not good, but it´s only the cabinet, i think i can fixit up, it have being inside always, and i got an extra chassis with it.

I started it slowly up and i hear sound in the speaker and shortly have som raster on the screen, but there is an issue, the Py500 is glowing up on the anode.. and it gets very fast, i measured the hor.osc signal and it´s okay, so the question is, what brings the py500 to glow??? i soldered the tripler off the secondary hight tension coil, but no changes.

 

Do anybody knows this chassis in GB? 

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Quote
Posted : 07/08/2017 8:19 am
Nuvistor
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Check the boost capacitor for short circuit.

Frank

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Posted : 07/08/2017 8:28 am
acj1980
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nuvistor said
Check the boost capacitor for short circuit.  

Yes i will, i was starring at it yesterday, i know the fault from the black&white televisions ;-), 

I return when i have checked it up 😉

 

Alex;-)

ReplyQuote
Posted : 07/08/2017 8:35 am
crustytv
(@crustytv)
Vrat Founder Admin

The service manual for the K80 is in the data library.

Alex you now have access to all the VIP areas which includes the data library. You may have to logout and back in again for access to work.

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Posted : 07/08/2017 8:52 am
PYE625
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acj1980 said

3.jpg  

 Hi Alex, nothing to do with the PY500, but it looks like the valve in your picture has lost vacuum?  

Interesting that it is the line driver PCF802....even if it has vacuum, the getter looks pretty poor so may be worth checking out.

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 07/08/2017 9:15 am
acj1980
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Chris said
The service manual for the K80 is in the data library.

Alex you now have access to all the VIP areas which includes the data library. You may have to logout and back in again for access to work.  

Thank you Chris 😀

 

About the pcf802 Andrew so don't worry, its from the extra chassis, the line tube on the chassis i have the issue is okay 😉

Alex;-)

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Posted : 07/08/2017 9:41 am
PYE625
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acj1980 said

 

About the pcf802 Andrew so don't worry, its from the extra chassis, the line tube on the chassis i have the issue is okay 😉

Alex;-)  

 Cool !  grin_gif

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 07/08/2017 9:45 am
acj1980
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Tonight i change the 0.1uF/1250volt capacistor, and it helps a lot, but sadly the PY500 is gone, it have being too hot on the anode, the other i have in stock dosent work proberly, so i have to find new one :-O 

 

Alex 😉 

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Posted : 07/08/2017 10:26 pm
PYE625
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Hi Alex, 

It may be that the PY500 was bad anyway, it will be interesting to see how a new one will work.

Keep a close eye on the new one and don't run the TV for very long if the anode becomes too hot.

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 07/08/2017 11:12 pm
acj1980
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PYE625 said
Hi Alex, 

It may be that the PY500 was bad anyway, it will be interesting to see how a new one will work.

Keep a close eye on the new one and don't run the TV for very long if the anode becomes too hot.  

Hi Pye625.

Thanks for your answer, i think you´re right about the new py500, i will keep an eye on it, the most weird things is that i have a NOS py500, but it dosent works, nothing happens if i put it in, can there be a different pinout? or what? the getter is blank so there must be vacuum inside, because it looks normal :-O 

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Posted : 08/08/2017 2:44 pm
PYE625
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acj1980 said

 i have a NOS py500, but it dosent works, nothing happens if i put it in, can there be a different pinout? or what? the getter is blank so there must be vacuum inside, because it looks normal :-O   

Hi Alex, it can be sometimes that new valves are defective. If it is a PY500, then the pin-out will be the same. You may use a PY500A which is probably more easily available.

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 08/08/2017 4:37 pm
acj1980
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PYE625 said

acj1980 said

 i have a NOS py500, but it dosent works, nothing happens if i put it in, can there be a different pinout? or what? the getter is blank so there must be vacuum inside, because it looks normal :-O   

Hi Alex, it can be sometimes that new valves are defective. If it is a PY500, then the pin-out will be the same. You may use a PY500A which is probably more easily available.  

Thanx Andrew.

 

I found one py500 in a box with other tubes, and the TV works fine for about 10 minutes, then the screen get´s black and the anode on the py500 get hot, i have a friend not far away from me, he have a new one i can get for free, so that is the next step.

 

Alex 😉 

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Posted : 08/08/2017 6:24 pm
Nuvistor
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You need to look for other reasons for the valve glowing, it is usually a fault in the TV not the valve itself.

Frank

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Posted : 08/08/2017 6:40 pm
PYE625
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nuvistor said
You need to look for other reasons for the valve glowing, it is usually a fault in the TV not the valve itself.  

100% Agree with that. 

One PY500 could have been faulty, but not two with hot anodes. The fault is somewhere else Alex.

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 08/08/2017 7:09 pm
acj1980
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nuvistor said
You need to look for other reasons for the valve glowing, it is usually a fault in the TV not the valve itself.  

Yes Frank.

But i really dont know what it could be, i replaced the booster cap, and that helps for a while, maybe it is the line transformer there is damaged

 

Alex 😉

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Posted : 08/08/2017 7:10 pm
PYE625
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Alex, I would check carefully the voltages around both PL509's. 

Don't fit a brand new PY500 until this fault is corrected. 

The line stage is complex and I do not fully understand it, but I would be surprised if the line transformer is faulty. It sounds like a resistor changing value, a leaky capacitor, or even a defective PL509.

Have you disconnected the tripler just in case it is dragging down the EHT?

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 08/08/2017 7:13 pm
Nuvistor
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I would often remove the screen feed to the PL509, appreciate there are two, and see if the PY500 still glows.

If it does, unless either the output valves have a S/C the fault must around the LOPTX circuits.

If the PY500 does not glow with the screen volts removed, check drive and the circuit around the output valves.

Edit, comments in addition to Andrews.

Frank

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Posted : 08/08/2017 7:23 pm
PYE625
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looking at the circuit, it seems both PL509's are effectively working together in parallel. 

Alex when the fault occurs, does the TV screen go blank very suddenly, or does the picture gradually become narrower and fade?

To understand the black art of electronics is to understand witchcraft.
Andrew.

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Posted : 08/08/2017 7:29 pm
crustytv
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Vrat Founder Admin

I seem to remember a thread on our old forum, another model of set had a very similar fault. I think it turned out to be green spot on the oscillator coil.

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Posted : 08/08/2017 7:43 pm
acj1980
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PYE625 said
Alex, I would check carefully the voltages around both PL509's. 

Don't fit a brand new PY500 until this fault is corrected. 

The line stage is complex and I do not fully understand it, but I would be surprised if the line transformer is faulty. It sounds like a resistor changing value, a leaky capacitor, or even a defective PL509.

Have you disconnected the tripler just in case it is dragging down the EHT?  

Hi Andrew.

I know, or else it get a short life, that make no sense, i tried earlier to disconnect the tripler, but without any diffrent, the pictures dissapers straight, not outfading, thats the weird, because i expected som slowly fading but no.

 

Frank ;-), i take a look on it tomorrow, now it´s time to relax an drink some coffey ;-), ohh by the way, you mentioned "the loptx" circuits, what is that in english? i´m sorry , but i am not educated in colour television, 🙁 

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Posted : 08/08/2017 7:47 pm
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