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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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12th Feb 2014, 9:00 pm | #21 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Hi Brian,
The EHT tray is a three stick doubler so there's not much can be done about reducing the high voltage by changing any components in that part of the set. The origins of the jellypot are unknown but it's likely it was removed from a Ferguson 900 series set. Tomorrow I'll experiment with additional resistors inserted in series in the HT supply to the anode of the PY81 boost diode. If I can find the correct VDR I'd reckon a stabilised line output stage is the answer to the width control and EHT voltage. DFWB. |
12th Feb 2014, 10:03 pm | #22 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Hi Robert,
Sadly it was a dud. I still have it and it was the original line OP transformer assembly that was carved up for the jellypot substitution. The set was made in early 1961 and is electrically similar as the 17" and 21" TG100 series receivers. It certainly has a strange look about it, a squared up 17TG100U in fact. Philips made a 23" version of this set, the 23TG107U. 405 only sets having the square 19" and 23" CRT are rare and were made between 1961 and 1962. Sales of new sets were hampered by the indecision about the future of British television. 625 or 405 lines? DFWB. |
12th Feb 2014, 11:32 pm | #23 |
Octode
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Re: Philips 19TG108U Not a success story.
Hello David, very sorry about the LOPT!
I may have some others somewhere, will have a look!! I had almost thought the tube was a more modern replacement but reading what you say I understand now!
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13th Feb 2014, 1:48 pm | #24 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Hi Robert,
Many thanks of for kind offer of another line output transformer but it is really not necessary. I might as well see this jellypot substitution project though having got as far as I have now. Today one of the HT sections of the mains dropper has failed so I will put the set aside for the time being until a replacement mains dropper can be found. DFWB. |
13th Feb 2014, 4:26 pm | #25 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Hi
How about removing one of the sticks in the tripler, assuming it's a open style unit? Glyn |
13th Feb 2014, 4:40 pm | #26 |
Dekatron
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Re: Philips 19TG108U Not a success story.
The EHT tray is a doubler unit so if a stick was removed it would simply become a half wave rectifier and the result would be insuffient EHT.
The answer is to either introduce a stabilising system similar to that used in the Feguson 900 series or go for the simple option of selected resistors in the anode feed of the booster diode. Minor corrections to the EHT versus width can be accomplished by altering the value of the flyback tuning capacitor. DFWB. |
23rd Oct 2021, 8:57 pm | #27 |
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Re: Philips 19TG108U Not a success story.
Re-opened at OP's request
Cheers Mike T
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25th Oct 2021, 10:42 pm | #28 |
Heptode
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Re: Philips 19TG108U Not a success story.
The Philips 19TG108U has been hibernating upstairs in the shop its been moved to downstairs this afternoon
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29th Oct 2021, 9:48 pm | #29 |
Dekatron
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Re: Philips 19TG108U Not a success story.
The attachment shows a rather scruffy line output transformer that was tried out in the set. It's faulty of course.
All the components on the sub chassis will be removed and the same type of components as used in the Stella ST1011U will be fitted, BRC 1500 Jellypot, width control resistors etc. DFWB. |
30th Oct 2021, 10:32 am | #30 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Over half an hour spent repairing the line linearity coil.
DFWB. |
30th Oct 2021, 2:03 pm | #31 |
Heptode
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Re: Philips 19TG108U Not a success story.
Hi David see you have took the set out of hibernation.
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30th Oct 2021, 3:01 pm | #32 |
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Re: Philips 19TG108U Not a success story.
The line output transformer will be removed from the sub-chassis later today.
Like the Stella ST1011U the octal plug and socket connection will be retained although the modified assembly will not be compatible with the original line output circuit. DFWB. |
30th Oct 2021, 6:19 pm | #33 |
Octode
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Re: Philips 19TG108U Not a success story.
This is one way to ensure a Philips has a reliable LOPT ! I didn't know Philips made a 19" version.
I had a 17" when I was at school one of my friends told me his parents had bought a new set and I could have the old one. His parents were proper old school Italian so before I was shown the set his mum insisted on feeding me! It was the biggest piece of lasagne I had ever seen!(and the first). She explained the set had a good picture but no "voice". I was shown to the coal shed and there sat on the remains of a heap of coal was the Philips TV. I can't remember what happened to it though, it was a while back! I am following with great interest! Rich.
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30th Oct 2021, 8:24 pm | #34 |
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Re: Philips 19TG108U Not a success story.
The 19" Philips is similar to the earlier 17TG100U, the main difference is that printed circuit boards replace the two handwired timebase sub-assemblies.
The IF and sound unit is handwired. The jellypot transformer is now in position and all the wiring in the line output stage box done. The transformer is positioned so that any BRC EHT doubler tray can be used. Provision for an alternative line output valve is made possible by fitting the adaptor plate shown in the attached picture. The PL81 is holding up well in the two modified 21" sets, the Philips 21TG100U and Stella ST1011U. The 19" set will like the 21" models have a 1ohm resistor inserted between the PL81 cathode and chassis. DFWB. Last edited by FERNSEH; 30th Oct 2021 at 8:37 pm. |
30th Oct 2021, 9:42 pm | #35 | |
Heptode
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Re: Philips 19TG108U Not a success story.
Quote:
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2nd Nov 2021, 11:06 am | #36 |
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Re: Philips 19TG108U Not a success story.
Results from yesterdays work on the set, a picture with excessive width.
Today, the EHT voltage will be measured and if it isn't too high the value of the flyback tuning capacitor will be reduced. That action will increase the EHT and reduce the picture width. At 182V the HT voltage is slightly low, about 10volts lower than the figure in the 1961/62 R & T servicing book. The Plessey scanning coils are of unknown origin. The Philips AT1030 coils can be tried again but it's likely insufficient width will be the result of using this coil set. EHT is supplied from a BRC doubler unit. DFWB. |
2nd Nov 2021, 6:23 pm | #37 |
Dekatron
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Re: Philips 19TG108U Not a success story.
The flyback tuning capacitor changed to the original value of 180pF. EHT is now 15.5KV but still too much picture width even with the width control on the minimum setting. The three 75 ohm resistors in series with the HT supply to the boost diode anode are in the circuit.
Also, the horizontal linearity is not good. This might be caused by the BRC 1500 line output transformer designed for 625 lines being used for the 405 line frequency of 10,125 c.p.s. DFWB. Last edited by FERNSEH; 2nd Nov 2021 at 6:30 pm. |
2nd Nov 2021, 8:41 pm | #38 |
Pentode
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Re: Philips 19TG108U Not a success story.
Well done on the conversion, i have used a BRC 950 jelly pot in a Pye 11u, works well on both standards and a BRC 980 jelly pot in a GEC BT 302.
How about trying a Lin sleeve shoved into the scan coils on your Philips? Would reduce the width and help with the poor Lin. |
2nd Nov 2021, 9:36 pm | #39 |
Nonode
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Re: Philips 19TG108U Not a success story.
Not miles out width wise, to be fair. David beat me to it with the suggestion of a lin sleeve. Looking at the screen shot, it doesn't look like it needs to be inserted too far.
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2nd Nov 2021, 9:45 pm | #40 |
Dekatron
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Re: Philips 19TG108U Not a success story.
Actually, it had crossed my mind this afternoon about using linearity sleeve to correct the horizontal linearity and possibly reduce the width. It's most likely the coils I'm presently using employed such a device.
Adjustment of the linearity coil has no effect. But before I do anything else let's see how the Philips AT1030 scanning coils work with the jellypot. DFWB. |