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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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24th Sep 2014, 5:33 pm | #1 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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1970s Ferguson model 3738 TV
Hi, a few years ago I bought a ferguson colour tv from the 70s. I powered it up but the cap across the mains went up in smoke and it went in the shed until today. I tried powering it up today and cut the cap before powering it up... there is currently no life at all from the set, fuses however are intact so do I need to replace the mains capacitor in order for the set to work?
any advice will be greatly appreciated! |
24th Sep 2014, 5:54 pm | #2 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: 1970s Ferguson TV
You can leave the capacitor across the mains disconnected, it will require replacement though when the tv is working.
Some Thorn TV's used a circuit breaker as well as fuses, this may need resetting. I would do some simple resistance checks across the mains supply and power supply before putting power back on again. I never fixed many Thorn sets, just the occasional one so expect much more advice to follow from other forum members. Frank |
24th Sep 2014, 6:01 pm | #3 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
Hi, thanks for the help, I've noticed it was also connected with a few resistors and a wire that leads to another circuit board so I wonder whether it should be there in order for it to power up? I've checked everything else but I'm baffled!
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24th Sep 2014, 6:22 pm | #4 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: 1970s Ferguson TV
The capacitor I thought you discussing is the one directly across the mains supply, if it is in the power supply then yes you may require it.
Have you got photos? |
24th Sep 2014, 6:30 pm | #5 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
Hi, I haven't got any photos at the moment, it is the one that is across the mains supply, its on the on/off switch
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24th Sep 2014, 6:43 pm | #6 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: 1970s Ferguson TV
You need to do some fault finding then unless Ferguson used that cap for something special, which I doubt. It is possible that the failure damaged items in the PSU, hence the suggestion of some simple meter tests.
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24th Sep 2014, 7:07 pm | #7 |
Octode
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,987
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Re: 1970s Ferguson TV
You may find the cap blowing has taken out one of the poles of the on/off switch. The fuses in the set or the plug should have blown first of course.
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Stephen _________"It`s only an old telly" ___ |
25th Sep 2014, 9:32 pm | #8 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
After looking at the set more I have found that it is a thorn 8800 chassis. On the PSU there is a resistor that seems to be overheating and it has burned most of the board. Would this need replacing or would there be another cause as to why it is overheating. I have managed to get the CRT heater to glow but the rest of the set is dead.
Thanks! |
26th Sep 2014, 12:33 pm | #9 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
Hi, if anyone has any circuit info regarding the 8800 chassis, could you possibly tell me what R704 is? It has no markings on it at all and I am unable to find any circuit information for it.
Thanks! |
26th Sep 2014, 5:23 pm | #10 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: 1970s Ferguson TV
I only have the circuit shown on pages 242-243 of the 1975-76 Servicing book.
R704 is listed as 51 ohms. Its in the collector of VT702, MJE520. Collector voltage = 35.V |
26th Sep 2014, 5:23 pm | #11 |
Triode
Join Date: Jan 2011
Location: Guildford, Surrey, UK.
Posts: 39
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Re: 1970s Ferguson TV
Is there a model number on the set anywhere
Likely to be 37?? |
27th Sep 2014, 10:44 am | #12 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
Hi, it is a model 3738.
Thanks for all the help! |
1st Oct 2014, 11:59 am | #13 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson TV
Hi, after looking more at the set today the symptoms are that it only powers the tube heaters, on the degauss board X801 (I believe is a PTC thermistor) is getting very hot as is R704 on the power board.
I have put in a request in the repairs wanted section as I'm not a fan of these tv's! However, should it be something relatively simple I'm happy to do it myself! Regards! Forgot to add, is there any chance it could be one of the transistors on the power supply board? Last edited by AC/HL; 1st Oct 2014 at 4:57 pm. Reason: PS merged |
1st Oct 2014, 3:46 pm | #14 |
Octode
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,987
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Re: 1970s Ferguson TV
Your reference to the diode BZX61C220, which was been deleted on your last edit would appear to be a 220volt zener. There are many components that will shut down the power supply. Your approach for asking for help in your area is a wise move I feel.
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Stephen _________"It`s only an old telly" ___ |
17th Oct 2014, 1:23 pm | #15 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson model 3738 TV
Hi everyone. Having replaced the power supply board I now have power to the rest of the set. There was still a fault with the resistor overheating but unplugging the Chroma, IF and video board (all one board) has stopped that from happening. Unplugging this has given me full EHT and the screen lighting up in a sort of purple colour. What should I now start checking on that board that could be causing the fault of the power resistor overheating?
Regards |
17th Oct 2014, 1:44 pm | #16 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: 1970s Ferguson model 3738 TV
After doing a little more poking around, unplugging P.L.4 on that board will make the set work fine with the Chroma etc board all plugged in. As soon as it is plugged in, the set goes dead again.
Regards |
17th Oct 2014, 10:18 pm | #17 |
Nonode
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
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Re: 1970s Ferguson model 3738 TV
Sounds like one of the tantalum capacitors has gone s/c - one of the ones across the 25V line.
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All the very best, Tas |