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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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8th Mar 2012, 11:05 am | #21 |
Octode
Join Date: Jan 2006
Location: Borough of Gateshead, UK.
Posts: 1,420
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Re: Der 5744
I remember reading something Les wrote about one of these sets in which an "engineer" had misadjusted the 30V line to 40Vish to mask a "corrulgated verticals" fault which soon resulted in the faliure of a major component.
Brian |
8th Mar 2012, 11:25 am | #22 | |
Hexode
Join Date: Aug 2008
Location: Essex, UK.
Posts: 370
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Re: Der 5744
Quote:
If you haven't already got it, search for and download the LLJALL.pdf file. Fascinating reading and easy to use PDF search to find a particular chassis.
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6.3v on my heaters is no longer enough to get me going in the morning!! |
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12th Mar 2012, 12:47 am | #23 |
Hexode
Join Date: Nov 2010
Location: Market Drayton, Shropshire, UK.
Posts: 485
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Re: Der 5744
hi
this could be due to over current trip circuit on the power board operating too early look for a 2watt carbon resister on the lower pcb i think it might be 1.8k or a 2.2k it will have gone low in value and might be getting warm. regards Derrick |
9th May 2012, 9:45 pm | #24 |
Hexode
Join Date: Dec 2011
Location: Wigan, Greater Manchester, UK.
Posts: 291
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Re: Der 5744
I am in the process of repairing a HMV 19 inch 3k.
I have been repairing the power board and have got as far as getting a picture with cogging and singing. About 1 inch in amplitude on both sides of the scan. I have replaced C619 140uF (a 220uF was fitted by someone before). R618 has been checked 150ohm. C631 replaced (10nF) W619 replaced. I have already changed W605 was zenering at 29V C609, C623 C624. The fault is on this board as I have tried a known good power board. Any ideas? Last edited by Davewantsone; 9th May 2012 at 9:54 pm. |
10th May 2012, 4:21 pm | #25 |
Hexode
Join Date: Dec 2011
Location: Wigan, Greater Manchester, UK.
Posts: 291
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Re: Der 5744
Well I sorted out the cogging and singing.
R628 which according to my circuit should be 2 ohms but had a 4R7 fitted. I had ignored this for it was as originally fitted. Now the Sept 77 Television magazine servicing details also shows this also as a 2ohm resistor. So I fitted a WW 2R2 and no more cogging. Could the board be a 3k5 model? Does anyone have a circuit diagram with this resistor as 4R7? |
10th May 2012, 7:58 pm | #26 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,819
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Re: Der 5744
Hi,
Just checked through both the 3000 and 3500 manuals, both state that R628 should be 2 ohms, I also looked at the 3000 modification sheet (mk II) and it's not mentioned as being changed at all on there, Looks like someone fitted the wrong value to your set! Regards, Lloyd. |
10th May 2012, 8:26 pm | #27 |
Hexode
Join Date: Dec 2011
Location: Wigan, Greater Manchester, UK.
Posts: 291
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Re: Der 5744
Thanks for checking. The resistor position for R628 was on the underside board which if different than the green 2 ohm resistor normally fitted on the top board which is the case for the other two power boards I have.
The resistor looked as if it had always been fitted since when the board was new! |
22nd Oct 2014, 9:48 pm | #28 |
Nonode
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
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Re: Der 5744
While looking up some other info on the Thorn 3000 series I came across this old thread and wondered if you ever got to the bottom of the fault Gary?
Regards, Tas |
22nd Oct 2014, 11:16 pm | #29 |
Hexode
Join Date: Nov 2010
Location: Market Drayton, Shropshire, UK.
Posts: 485
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Re: Der 5744
Hi
This fault is possibly on the power supply. It could be the over-current trip circuit operating too early. Possible cause is a 2 watt carbon resistor mounted on the lower psu board; it stands vertical near to the over-current preset. I think it is a 2k2 but not certain; it goes low resistance. Regards Derrick |
25th Oct 2014, 12:26 pm | #30 |
Pentode
Join Date: Feb 2006
Location: County Durham, UK.
Posts: 234
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Re: Der 5744
Hi
To be honest I put the set to one side and have forgotten about it. I'm recovering from an arm injury at the moment, so can"t lift tellys. Once I'm fit I'll get back to the set and see if we can get to the bottom of it. Regards. Gary. |
26th Oct 2014, 3:14 pm | #31 |
Nonode
Join Date: May 2006
Location: St Albans, Herts, UK.
Posts: 2,193
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Re: Der 5744
Take care for now mate. I look forward to the telly's next outing
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All the very best, Tas |