Sony Trinitron KV-M1440U Power & Picture Issues - UK Vintage Radio Repair and Restoration Discussion Forum

Dusklo21 · 27th Dec 2021, 4:34 pm

Before I start, I want to say that I'm new here. I've read the rules and I believe I'm putting this in the right place, but feel free to correct me.

Recently I got a Sony Trinitron KV-M1440U off of Gumtree in decent condition. I just plan to use it for gaming. But when I got it home, there were some issues. I have to hold the power button in to get the TV to stay on because if I let go, it simply turns off. And the picture is a mixed bag, it looks good for a CRT apart from two glaring issues, the top of the screen is noticibly more white at the top than at the bottom, and while normal video looks decent, any big solid colours cause head-splitting flickering.

Thus far I have tried unplugging it and leaving it and then holding the power button while unplugged and then plugged but to no avail. I have ordered a remote from eBay so I should be able to access the service menu.

I have a smattering of knowledge with CRTs but I'm still mostly a novice so any advice at all would be much appriciated.

1955APREN · 27th Dec 2021, 10:22 pm

Hi
Nice to have you on forum.
I suspect that the on off switch is faulty not latching on , but might be
just the knob not making[ good contact with the switch. is it possible to remove
the chassis from the cabinet ,up plug set from mains and with a meter
test both poles for a circuit. If the switch will not stay latched in then the switch is faulty. If you can take a photo of the switch I might be able
to find a replacement , Also could you take photo of you colour fault
this might help in giving further advice.
kind regards
Derrick

Dusklo21 · 28th Dec 2021, 12:52 am

Thanks for your response! I don't have any pictures of the switch but I plan to open the TV and safely discharge it before doing anything. I do have photos of the picture that I can show just now though.

In the first picture, you can see a green halo around the almost completely white text, and in the second you can see that its brighter at the top than at the bottom.

There is also a strong and head-splitting flicker when there's a solid colour.

Heatercathodeshort · 28th Dec 2021, 5:49 pm

First item to check is the electrolytic capacitor that decouples the supply to the red/blue/green output transistors. Check the main printed panel for cracks. The on/off switch being damaged makes me think it may have had a fall. John.

HamishBoxer · 28th Dec 2021, 6:27 pm

Check any elec caps that are fed by diodes off the line transformer.

Dusklo21 · 29th Dec 2021, 1:31 pm

I have opened up the TV so I could at least try and see what's up with the power button. Nothing appears obviously wrong with either the switch or the hole it pokes through. Nothing was loose in the plastic housing either. All I got from this was that it must be either the switch or, god forbid, the board. I also came to the conclusion that this must be the dustiest TV in Scotland. Every inch of the board and every wire was caked in this magnetic dust. Maybe this Trinitron wasn't such a great purchase.

I also got a nasty wee shock from somewhere on the board. I discharged the anode with crocodile leads on a wooden-handle screwdriver to one of the screws holding the front of the CRT into the casing but I still got a shock anyway, just my luck. It wasn't too bad, I suspect that having left it unplugged for 12 hours and holding in the power switch a few times made it infinitely less lethal but like I said, I'm a novice.

Really at a loss with this power switch. The actual TV works fine and I suspect that most or all of my picture problems will be sorted with the service menu.

Dusklo21 · 29th Dec 2021, 1:33 pm

Quote:

Originally Posted by Heatercathodeshort

First item to check is the electrolytic capacitor that decouples the supply to the red/blue/green output transistors. Check the main printed panel for cracks. The on/off switch being damaged makes me think it may have had a fall. John.

No cracks or problems on the board that I can see, just lots of dust.

G6ONEDave · 29th Dec 2021, 2:54 pm

The power switch is faulty due to the internal latching pin either missing, broken or its trackway damaged. The cure is a replacement switch. If you can find out the history of the Sony CTV, try to see if it's had the CRT boosted/rejuvenated, otherwise I think that the green needs adjusting as to me it seems to be the strongest colour and is set too high, hence the flaring.

When discharging the EHT take the croc clip to the braid across the outer CRT Aquadag coating and not the fixing screw. The fixing screw may or may not be connected to the earthy side of the circuit. An internal picture would help to confirm that. Also remember that the final anode is not the only area that bites. Any of the high voltage electrolytic capacitors can also give a bite from stored electricity.

Dave

JonSnell · 29th Dec 2021, 3:14 pm

The final anode supply is a coaxial connector. Be careful otherwise it will fall to bits.
They were very reliable TVs.
Check +B is 118 - 120volts and steady.
With the brightness ad contrast at zero, set the grey scale. Set the G2 control to a dimly illuminated frame.
I would avoid using the four pin socket to adjust the firmware settings, it can easily end the use of the TV.

The on off switch may be faulty as there was a recall on all Sony TVs of that era. I probably have one and a green sticker, if you need one. Not sure it has the wiper remote controller contacts though.
Insert a test pattern and return brightness and contrast to normal viewing settings.

I found that the dustier the TV set, the cleaner the household it came from due to the EHT attracting the dust from the lady of the house doing her dusting.

its ur aerial · 29th Dec 2021, 3:14 pm

I have to agree with G6ONEDave, its a defective mains switch, Sony switches on a lot of their models were a common failure, sometimes just be removing the retains screws it will relatch itself and start working correctly for a short time.
As for the green, you could try adjusting the Green drive, and checking a few caps, but most likely the Tube is flat, some one may in the past tried to boost it, but from memory Sony CRT`s didn't take too well to boosting.
Can't remember, if this has one, but a lot of CRT sets had a low value resister in series with the CRT heater supply, if it does have one, try shorting it out to increase the heater voltage, you may get a result, but it's only a temporary fix.

Ken, G6HZG, VMARS, AM ARS.

Maarten · 29th Dec 2021, 3:42 pm

I don't assume the tube is flat, that didn't happen too often in modernish small screen sets, not even Trinitrons. Either the supply to the drive transistors is faulty (low or ripply) or the G2 and bias/drive settings need adjustment.

greg_simons · 29th Dec 2021, 5:33 pm

Just thinking on that coaxial final anode connector, there's something at the back of my mind that incorrect g2 adjustment could cause a very wierd picture effect, might be worth pursuing.
Greg.

Maarten · 29th Dec 2021, 6:38 pm

This tube would have its HSTAT connected through the socket instead of a coaxial final anode connector, with the HSTAT control where you would expect the G3 (focus) potentiometer.

FrankB · 30th Dec 2021, 2:33 am

While you are in the set, check the H driver tx for ring cracks, and be sure to replace the small value cap, typically .1 to 1 mfd 'lytic in the H driver trans ckt. They WILL fail taking the HOT with it. Use a 105C rated cap of the best quality you can find. High failure item.
I also replaced a lot of those Sony power switches, as the contacts would fail or the capture detent in them would break. Look over the PC board got ring cracks on the audio IC, vert IC, HOT and such, plus any transformers or chokes mounted to the main PC board.

Heatercathodeshort · 30th Dec 2021, 11:10 am

The HT supply for the RGB output transistors is derived from the line output stage via a diode and an electrolytic capacitor.

Can you confirm you have checked these components? If faulty the effect can be similar to a faulty CRT often producing a bad picture when the A1 control is increased in an attempt to get a picture. Before you go into complicated fault finding procedures I would suggest you check these points first. J.

its ur aerial · 1st Jan 2022, 6:58 am

Quote:

Originally Posted by greg_simons

Just thinking on that coaxial final anode connector, there's something at the back of my mind that incorrect g2 adjustment could cause a very wierd picture effect, might be worth pursuing.
Greg.

Now rings a bell with me as well

Ken G6HZG

Happy 2022.

murphyv310 · 1st Jan 2022, 9:32 am

Hi.
Fixed many of these while working with Sony.
The problem is quite simple. 1, replace the switch 2, set up the G2, 3, check the +B voltage and then go from there.
The CRT should be OK but exceptions can happen.
Do not update the firmware as you'll land up with issues I can guarantee it. We NEVER updated firmware on this set, any parameters were set with the remote control.

Maarten · 1st Jan 2022, 12:23 pm

I seem to remember updating the firmware would involve desoldering and replacng the processor, so it makes sense not to do that.

Dusklo21 · 1st Jan 2022, 3:59 pm

Hello, sorry for my abcense. I've decided to just leave this TV. I thought some of the repairs would be manageable for me, however it seems like I'd like some equipment I don't have and it's ultimately easier for me to sell it as spares.

However, there is a silver lining. For £15, I picked up a Sony Trinitron KV-V32FX68U. It's a beast. It was hard to get into the house but it's quite astounding. Thanks for all your help but this thread is now kinda over.

27th Dec 2021, 4:34 pm	#1
Dusklo21 Diode Join Date: Dec 2021 Location: Stirlingshire, Scotland, UK. Posts: 5	Sony Trinitron KV-M1440U Power & Picture Issues Before I start, I want to say that I'm new here. I've read the rules and I believe I'm putting this in the right place, but feel free to correct me. Recently I got a Sony Trinitron KV-M1440U off of Gumtree in decent condition. I just plan to use it for gaming. But when I got it home, there were some issues. I have to hold the power button in to get the TV to stay on because if I let go, it simply turns off. And the picture is a mixed bag, it looks good for a CRT apart from two glaring issues, the top of the screen is noticibly more white at the top than at the bottom, and while normal video looks decent, any big solid colours cause head-splitting flickering. Thus far I have tried unplugging it and leaving it and then holding the power button while unplugged and then plugged but to no avail. I have ordered a remote from eBay so I should be able to access the service menu. I have a smattering of knowledge with CRTs but I'm still mostly a novice so any advice at all would be much appriciated.

27th Dec 2021, 10:22 pm	#2
1955APREN Heptode Join Date: Nov 2010 Location: Market Drayton, Shropshire, UK. Posts: 532	Re: Sony Trinitron KV-M1440U Power & Picture Issues Hi Nice to have you on forum. I suspect that the on off switch is faulty not latching on , but might be just the knob not making[ good contact with the switch. is it possible to remove the chassis from the cabinet ,up plug set from mains and with a meter test both poles for a circuit. If the switch will not stay latched in then the switch is faulty. If you can take a photo of the switch I might be able to find a replacement , Also could you take photo of you colour fault this might help in giving further advice. kind regards Derrick

28th Dec 2021, 12:52 am	#3
Dusklo21 Diode Join Date: Dec 2021 Location: Stirlingshire, Scotland, UK. Posts: 5	Re: Sony Trinitron KV-M1440U Power & Picture Issues Thanks for your response! I don't have any pictures of the switch but I plan to open the TV and safely discharge it before doing anything. I do have photos of the picture that I can show just now though. In the first picture, you can see a green halo around the almost completely white text, and in the second you can see that its brighter at the top than at the bottom. There is also a strong and head-splitting flicker when there's a solid colour. Attached Thumbnails

28th Dec 2021, 5:49 pm	#4
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,169	Re: Sony Trinitron KV-M1440U Power & Picture Issues First item to check is the electrolytic capacitor that decouples the supply to the red/blue/green output transistors. Check the main printed panel for cracks. The on/off switch being damaged makes me think it may have had a fall. John.

28th Dec 2021, 6:27 pm	#5
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 9,208	Re: Sony Trinitron KV-M1440U Power & Picture Issues Check any elec caps that are fed by diodes off the line transformer. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

29th Dec 2021, 1:31 pm	#6
Dusklo21 Diode Join Date: Dec 2021 Location: Stirlingshire, Scotland, UK. Posts: 5	Re: Sony Trinitron KV-M1440U Power & Picture Issues I have opened up the TV so I could at least try and see what's up with the power button. Nothing appears obviously wrong with either the switch or the hole it pokes through. Nothing was loose in the plastic housing either. All I got from this was that it must be either the switch or, god forbid, the board. I also came to the conclusion that this must be the dustiest TV in Scotland. Every inch of the board and every wire was caked in this magnetic dust. Maybe this Trinitron wasn't such a great purchase. I also got a nasty wee shock from somewhere on the board. I discharged the anode with crocodile leads on a wooden-handle screwdriver to one of the screws holding the front of the CRT into the casing but I still got a shock anyway, just my luck. It wasn't too bad, I suspect that having left it unplugged for 12 hours and holding in the power switch a few times made it infinitely less lethal but like I said, I'm a novice. Really at a loss with this power switch. The actual TV works fine and I suspect that most or all of my picture problems will be sorted with the service menu.

29th Dec 2021, 2:54 pm	#8
G6ONEDave Nonode Join Date: Dec 2019 Location: Owston Ferry, North Lincolnshire, UK. Posts: 2,112	Re: Sony Trinitron KV-M1440U Power & Picture Issues The power switch is faulty due to the internal latching pin either missing, broken or its trackway damaged. The cure is a replacement switch. If you can find out the history of the Sony CTV, try to see if it's had the CRT boosted/rejuvenated, otherwise I think that the green needs adjusting as to me it seems to be the strongest colour and is set too high, hence the flaring. When discharging the EHT take the croc clip to the braid across the outer CRT Aquadag coating and not the fixing screw. The fixing screw may or may not be connected to the earthy side of the circuit. An internal picture would help to confirm that. Also remember that the final anode is not the only area that bites. Any of the high voltage electrolytic capacitors can also give a bite from stored electricity. Dave __________________ Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica)

29th Dec 2021, 3:14 pm	#9
JonSnell Heptode Join Date: Oct 2019 Location: Weymouth, Dorset, UK. Posts: 631	Re: Sony Trinitron KV-M1440U Power & Picture Issues The final anode supply is a coaxial connector. Be careful otherwise it will fall to bits. They were very reliable TVs. Check +B is 118 - 120volts and steady. With the brightness ad contrast at zero, set the grey scale. Set the G2 control to a dimly illuminated frame. I would avoid using the four pin socket to adjust the firmware settings, it can easily end the use of the TV. The on off switch may be faulty as there was a recall on all Sony TVs of that era. I probably have one and a green sticker, if you need one. Not sure it has the wiper remote controller contacts though. Insert a test pattern and return brightness and contrast to normal viewing settings. I found that the dustier the TV set, the cleaner the household it came from due to the EHT attracting the dust from the lady of the house doing her dusting. __________________ Valve equipment repairs since 1968 https://jonsnell.co.uk

29th Dec 2021, 3:14 pm	#10
its ur aerial Heptode Join Date: May 2009 Location: Ryde, Isle of Wight, UK. Posts: 617	Re: Sony Trinitron KV-M1440U Power & Picture Issues I have to agree with G6ONEDave, its a defective mains switch, Sony switches on a lot of their models were a common failure, sometimes just be removing the retains screws it will relatch itself and start working correctly for a short time. As for the green, you could try adjusting the Green drive, and checking a few caps, but most likely the Tube is flat, some one may in the past tried to boost it, but from memory Sony CRT`s didn't take too well to boosting. Can't remember, if this has one, but a lot of CRT sets had a low value resister in series with the CRT heater supply, if it does have one, try shorting it out to increase the heater voltage, you may get a result, but it's only a temporary fix. Ken, G6HZG, VMARS, AM ARS. __________________ Life is not Hollywood, life is Cricklewood. Last edited by its ur aerial; 29th Dec 2021 at 3:16 pm. Reason: spelling.

29th Dec 2021, 3:42 pm	#11
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,775	Re: Sony Trinitron KV-M1440U Power & Picture Issues I don't assume the tube is flat, that didn't happen too often in modernish small screen sets, not even Trinitrons. Either the supply to the drive transistors is faulty (low or ripply) or the G2 and bias/drive settings need adjustment.

29th Dec 2021, 5:33 pm	#12
greg_simons Octode Join Date: Jul 2004 Location: Evesham, Worcestershire, UK. Posts: 1,555	Re: Sony Trinitron KV-M1440U Power & Picture Issues Just thinking on that coaxial final anode connector, there's something at the back of my mind that incorrect g2 adjustment could cause a very wierd picture effect, might be worth pursuing. Greg. __________________ Picture, sound?, DOOR.

29th Dec 2021, 6:38 pm	#13
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,775	Re: Sony Trinitron KV-M1440U Power & Picture Issues This tube would have its HSTAT connected through the socket instead of a coaxial final anode connector, with the HSTAT control where you would expect the G3 (focus) potentiometer.

30th Dec 2021, 2:33 am	#14
FrankB Heptode Join Date: Oct 2005 Location: Olympia, Washington, USA. Posts: 734	Re: Sony Trinitron KV-M1440U Power & Picture Issues While you are in the set, check the H driver tx for ring cracks, and be sure to replace the small value cap, typically .1 to 1 mfd 'lytic in the H driver trans ckt. They WILL fail taking the HOT with it. Use a 105C rated cap of the best quality you can find. High failure item. I also replaced a lot of those Sony power switches, as the contacts would fail or the capture detent in them would break. Look over the PC board got ring cracks on the audio IC, vert IC, HOT and such, plus any transformers or chokes mounted to the main PC board.

30th Dec 2021, 11:10 am	#15
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,169	Re: Sony Trinitron KV-M1440U Power & Picture Issues The HT supply for the RGB output transistors is derived from the line output stage via a diode and an electrolytic capacitor. Can you confirm you have checked these components? If faulty the effect can be similar to a faulty CRT often producing a bad picture when the A1 control is increased in an attempt to get a picture. Before you go into complicated fault finding procedures I would suggest you check these points first. J.

1st Jan 2022, 9:32 am	#17
murphyv310 No Longer a Member Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,491	Re: Sony Trinitron KV-M1440U Power & Picture Issues Hi. Fixed many of these while working with Sony. The problem is quite simple. 1, replace the switch 2, set up the G2, 3, check the +B voltage and then go from there. The CRT should be OK but exceptions can happen. Do not update the firmware as you'll land up with issues I can guarantee it. We NEVER updated firmware on this set, any parameters were set with the remote control.

1st Jan 2022, 12:23 pm	#18
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,775	Re: Sony Trinitron KV-M1440U Power & Picture Issues I seem to remember updating the firmware would involve desoldering and replacng the processor, so it makes sense not to do that.

1st Jan 2022, 3:59 pm	#19
Dusklo21 Diode Join Date: Dec 2021 Location: Stirlingshire, Scotland, UK. Posts: 5	Re: Sony Trinitron KV-M1440U Power & Picture Issues Hello, sorry for my abcense. I've decided to just leave this TV. I thought some of the repairs would be manageable for me, however it seems like I'd like some equipment I don't have and it's ultimately easier for me to sell it as spares. However, there is a silver lining. For £15, I picked up a Sony Trinitron KV-V32FX68U. It's a beast. It was hard to get into the house but it's quite astounding. Thanks for all your help but this thread is now kinda over.