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 Post subject: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Nov 11, 2019 8:38 am 


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Greeting everyone.
I bought a Sony PVM 14M4 and it had the three RGB lines on top of the screen and they were visible in the main menu OSD. The lines had shifted the menu OSD down the screen a bit but still visible.
I went to service menu and went to V BLANKING 60 and changed the value until the lines went above the viewable area and finally disappeared. Menu OSD was now perfectly placed.
NOW - as that happpened and I was very happy - the display suddenly went blank and nothing on screen. In my desperation I pressed a few buttons but nothing. I most probably also pressed "Degauss" which I believes writes your service menu changes but nothing happened. I turned it off and on and also plugged my console but I cant get anythying to display. Not even the OSD Menu. the CRT still turns on and off but no display.

Please can anyone assist me with this.

Many thanks.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Thu Nov 28, 2019 5:51 pm 


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Update -
The screen turns on and after a couple of minutes it turns green with faint horizontal lines.
I have opened up the unit and have no issues accessing components. If anyone can guide me as to what might be casuing this. it will be much appreciated.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Fri Nov 29, 2019 11:24 pm 



Joined: 25 Nov 2019
Posts: 29
Maybe you need to factory reset the unit. The lines were originally caused by failing capacitors in the geometry circuit on the main board located near the flyback. try this. This will at least hopefully bring you back to where you can see the image. You probably brought blanking out of range.

Turn on monitor.
Press:
MENU
ENTER+DEGAUSS
3x DOWN
ENTER
3x DOWN
3x ENTER

If monitor doesn't reset, power it off and back on.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Sat Nov 30, 2019 3:11 pm 


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freakaftr8 wrote:
Maybe you need to factory reset the unit. The lines were originally caused by failing capacitors in the geometry circuit on the main board located near the flyback. try this. This will at least hopefully bring you back to where you can see the image. You probably brought blanking out of range.

Turn on monitor.
Press:
MENU
ENTER+DEGAUSS
3x DOWN
ENTER
3x DOWN
3x ENTER

If monitor doesn't reset, power it off and back on.


Thank you freakaft8. Someone finally replied.
I tried exaclt this right now but unfortunately nothing. Is that a way to reset 14M4 too. I thought this was posted before for the 14L2 which has different way of resetting I think.
I have also tried all the factory reset methods in the manual of PVM-14M4 and nothing.

If vblanking was out of range then I would expect to see all black. But I am seeing a greenish screen with very faint horizontal lines.

https://pasteboard.co/IJ64CX9.jpg

Not sure if vblanking caused it as the seconds before it went bad I had adjusted the vblanking 60 so the OSD Menu was perfectly placed on the screen and the last line of the three RGB lines had just vansihed over the visible area. It may be that triggered something or something else entirely that happened at the same time.

I have opened the unit - reseated all ribbon cables. checked the voltages of transistors on the neckboard and that looks ok.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 02, 2019 7:27 am 



Joined: 25 Nov 2019
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After thinking about it I do not think that the screen would blank out sitting on its own before you pressed the degauss button. You would have had to press that degauss button twice to write the parameters.. I have a feeling something else has taken place because if vertical blanking was out of range I do not believe you would even have a green background with retrace. Obviously your vertical deflection is working or you would have no picture. Not even a faint raster. I believe something else is going on here. There is no data being sent to the drivers. Have a look at any connections or cables that go from the neck board to the main board. Also look at your jungle IC. It's the one that says SONY AX------- on it. Tap on it and see if there is a bad connection somewhere. I've had similar with Trinitrons before. Try gently tapping around the board.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 02, 2019 12:49 pm 


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freakaftr8 wrote:
After thinking about it I do not think that the screen would blank out sitting on its own before you pressed the degauss button. You would have had to press that degauss button twice to write the parameters.. I have a feeling something else has taken place because if vertical blanking was out of range I do not believe you would even have a green background with retrace. Obviously your vertical deflection is working or you would have no picture. Not even a faint raster. I believe something else is going on here. There is no data being sent to the drivers. Have a look at any connections or cables that go from the neck board to the main board. Also look at your jungle IC. It's the one that says SONY AX------- on it. Tap on it and see if there is a bad connection somewhere. I've had similar with Trinitrons before. Try gently tapping around the board.


Yes agreed. I also think that after adjusting VBLANKING 60 - something else snapped.
The faint raster is all I get and nothing. Also when I press 16:9 mode - I get faint blackish cloudiness on the upper and lower edges of the screen which are suppose to solid black borders for 16:9 mode.
And yeah not even a faint sign of actual video feed.

There are two V BLK OUT transistors on the neckboard and one of them isn't giving proper voltage reading (i think so as all three legs measure under 1V) so I have ordered that from Hong Kong. Faint hope that'll fix it but I really don't know what else to do. I have already replaced the G DRIVE transistor on the neckboard and although it is giving correct voltage now - it made no differece.

Can ou tell me where to find the "Jungle IC" as I have been through the manual and cant find any mention of it or a part starting with AX.

Thanks


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 02, 2019 2:21 pm 


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Is that the jungle IC on the A-board/Mainboard?

https://pasteboard.co/IJoExL4.jpg

I have checked the connections between the Neckboard and the mainboard and to my eye it looks OK.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 02, 2019 7:02 pm 



Joined: 25 Nov 2019
Posts: 29
No. That's the parameter processor. the jungle is the one to the right in that picture. looks similar but it's hard soldered to the board. It will have the Sony logo on it. If any of those transistors failed on the board, you will have a bright raster with the failed transistor of the color that failed as it will cause a collector to base short. You could give a go at recapping the neckboard itself and look for a 39 ohm resistor on the neckboard that could go open. But usually that will result in a white screen with AKB shutdown. What is the output voltage to the drives on the neckboard? There should be a connector going to the neckboard with about 180v or so. Also while in there, there are two or 3 capacitors near the flyback that should be replaced for the original deflection issue. Yiu never know, that could solve the issue as well.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 02, 2019 8:54 pm 


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freakaftr8 wrote:
No. That's the parameter processor. the jungle is the one to the right in that picture. looks similar but it's hard soldered to the board. It will have the Sony logo on it. If any of those transistors failed on the board, you will have a bright raster with the failed transistor of the color that failed as it will cause a collector to base short. You could give a go at recapping the neckboard itself and look for a 39 ohm resistor on the neckboard that could go open. But usually that will result in a white screen with AKB shutdown. What is the output voltage to the drives on the neckboard? There should be a connector going to the neckboard with about 180v or so. Also while in there, there are two or 3 capacitors near the flyback that should be replaced for the original deflection issue. Yiu never know, that could solve the issue as well.


Yes the raster screen is just dim green and not bright so probably its not the RGB transistors on the neckboard causing this. Also it takes it a couple of minutes for the screen to turn greenish from black when switched on from cold state.
From the RGB Drive transistors on the neckboard I was getting 11.4V on one of the three legs and other legs gave around 1-2V. Also on quite a few transistors on the neckboard I was getting 184V (I believe on RGB Buffer and Out transistors) so I guess the neckboard is getting its 180V or so via that pin in the ribbon connector connected to the mainboard.

Also additional info: when I switch off the monitor the screen doesn't instantly go black but instead there is a splash of bright colours around the mid of screen that converges in vertically and then horizontally and then the CRT switches off. I can upload a picture of that if you like. Does it indicate a fault in the CRT itself?

I understand there are quite a few variables here that can be causing it but lets start with the most likely ones and we can hopefully go about process of elimination. I know the couple of transistors near the flyback you referred to related to the deflection and the initial issue causing the RGB lines to appear however it is unlikely that may be causing the current problem. Also dont know if it will be possible to find the jungle IC spare part in case that is faulty. But I will come to these as a last resort. Also the A-board/motherboard is a real pain to take out but as I said I will if all else fails.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Tue Dec 03, 2019 4:47 am 



Joined: 25 Nov 2019
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Z red green blue splash when you turn it monitor off is normal. That indicates that the CRT is in fact working and it has deflection so your problem would be around the jungle processor where the outputs go to the neck board something there is not right. Other than that I'm not sure except for the fact that something is out of sync. Having no OSD indicates that there is a problem on the jungle. I suppose you could take a can of freeze spray or duster spray and turn it outside down and freeze around the processor and capacitors in that area in look for a change while it's on.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Tue Dec 03, 2019 9:06 am 


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freakaftr8 wrote:
Z red green blue splash when you turn it monitor off is normal. That indicates that the CRT is in fact working and it has deflection so your problem would be around the jungle processor where the outputs go to the neck board something there is not right. Other than that I'm not sure except for the fact that something is out of sync. Having no OSD indicates that there is a problem on the jungle. I suppose you could take a can of freeze spray or duster spray and turn it outside down and freeze around the processor and capacitors in that area in look for a change while it's on.


When I get home tonight I will have a close look at the Jungle IC and see if the spare part can still be bought on Ebay or something -however seems unlikely. Would voltage checking each pin be indicative of it being faulty or there is no way of telling? Also I am not familiar with the freezing around the processor method and observing chage. Could you please elaborate? I have a compressed air cannister.

So would you rule out the Flyback transformer being faulty as not being able to generate enough initial voltage of 28KV to show the picture?

Also would you rule out an issue with the cathode/anodes or other internal components of the tube starting from the point it attaches to the neckboard?


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Tue Dec 03, 2019 4:29 pm 



Joined: 25 Nov 2019
Posts: 29
Since you have a raster I seriously doubt anything is wrong with the CRT. They are not displaying the data that should be coming from the processor so the processor is not emitting data. Sense there is obviously an original problem with the deflection circuit capacitors because of the original issue with the red green blue line on top, Take your can, hold it upside down, point it at the jungle ic and surrounding components, including any capacitors, and spray them for about 3 seconds. Do this quickly watch the screen to see if there is any change at all. Usually where there's one failed capacitor there are more. I doubt there's anything wrong with the jungle except for components around it that control the driving. That would be my primary focus. This area controls what gets displayed to the screen.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Tue Dec 03, 2019 5:10 pm 


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OK thanks. So I will focus on the mainboard with deflection components for now.
I will update with my findings.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Thu Dec 05, 2019 11:26 am 


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I have taken out the motherboard and visually I am not able to see anything bad.

Here is the motherboard
https://pasteboard.co/IJPN5sA.jpg

And here are the two caps for RGB retrace lines.
https://pasteboard.co/IJPNDJH.jpg

I have ordered the new caps so will replace the two C572 and C584. Also one of the VBlank Out caps on the neckboard.

Is there anything else you can observe or Is hould check meanwhile?


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Thu Dec 05, 2019 2:38 pm 



Joined: 25 Nov 2019
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Lo oks like you are on the right track. I would have a look at the solder on the bottom of ic404 jungle ic while its out. look for any cracked solder joints on the board.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Fri Dec 06, 2019 9:27 am 


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Checked the back of IC04. Soldier joints look solid and good. I cant really see any damage at all to any of the boards or components.
If the video processing circuitary is bad ie IC04 in this case - would you expect to see a faint raster on the screen or total black?


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Sat Dec 07, 2019 9:35 pm 



Joined: 25 Nov 2019
Posts: 29
I just thought about it again and when you turn it off and you get the red green blue Flash in the middle the picture that is not normal.. This is what happened to me on both of my PV m's when I had a shorted rectifier diode and and open inductor on the output channel to the neckboard. Feel for a 450 V 100 micro farad capacitor that is near the connector that goes to the neckboard. Is it getting hot at all?


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Sun Dec 08, 2019 5:34 pm 


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I have been trough the service manual and also visually but not able to find a capacitor of 100MF 450V rating on the mainboard. Would that be a blue ceramaic or an electrolyte capacitor. Any chance you would know the capacitor number?
Also regarding the RGB colour splash in the middle of the screen when turning it off - I had read somewhere that would be indicative of bad CRT.
I am happy to look into other components if you are confident in ruling out it being a bad CRT or flyback.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Wed Dec 11, 2019 3:24 pm 



Joined: 25 Nov 2019
Posts: 29
Sorry was out for a few days sick. The section im focused on is the capacitor right near the fly back is the biggest one and it's near the output connector that goes to the neckboard. I was looking back at your pictures and it doesn't look like its domed or anything it's most likely ok. I have one of you're pictures that you took earlier circled but I can't post it but it's not a big deal it's easy to find this.Look for the biggest capacitor on the board on the corner ( The reason you can't find that capacitor is because it's a smaller rated value considering that you only have a 117 V or so going to the CRT transistors wear mine being a 19 inch is more voltage hence bigger capacitance sorry)

I'm curious as to what the screen does when it's completely black with a little bit of a green tint you say, turn up the brightness does it get brighter ? does it show the black background in under scan mode. Also if you turn up the brightness does it change?

I don't know if I ask before but if you're sending a signal to it and you're not getting video are you getting sound? And if you are getting sound does the brightness and contrast change the picture at all? As in does it get brighter or dimmer black

If the brightness changes that it's something in a video circuit. If the brightness does not change when you're supplying video then it's being blanked by the processor in in that case if it won't come back by a series of reset tricks then the jungle or the Eeprom holding the information is most likely bricked. I I believe the processor storing the settings is that big NEC IC that can be removed from the board that looks similar to the jungle IC that you thought was a jungle IC at 1st

Edit: yes it's an electrolytic capacitor.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Thu Dec 12, 2019 4:08 pm 


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freakaftr8 wrote:
Sorry was out for a few days sick. The section im focused on is the capacitor right near the fly back is the biggest one and it's near the output connector that goes to the neckboard. I was looking back at your pictures and it doesn't look like its domed or anything it's most likely ok. I have one of you're pictures that you took earlier circled but I can't post it but it's not a big deal it's easy to find this.Look for the biggest capacitor on the board on the corner ( The reason you can't find that capacitor is because it's a smaller rated value considering that you only have a 117 V or so going to the CRT transistors wear mine being a 19 inch is more voltage hence bigger capacitance sorry)

I'm curious as to what the screen does when it's completely black with a little bit of a green tint you say, turn up the brightness does it get brighter ? does it show the black background in under scan mode. Also if you turn up the brightness does it change?

I don't know if I ask before but if you're sending a signal to it and you're not getting video are you getting sound? And if you are getting sound does the brightness and contrast change the picture at all? As in does it get brighter or dimmer black

If the brightness changes that it's something in a video circuit. If the brightness does not change when you're supplying video then it's being blanked by the processor in in that case if it won't come back by a series of reset tricks then the jungle or the Eeprom holding the information is most likely bricked. I I believe the processor storing the settings is that big NEC IC that can be removed from the board that looks similar to the jungle IC that you thought was a jungle IC at 1st

Edit: yes it's an electrolytic capacitor.


Hi. Thanks for replying.
Yes I do see a big capacitor near the connector for the neckboard. It has rating 100v 470uF. could it be that you got these reading other way around?
But you are saying that this capacitor is unlikely to be at fault here right? Also it looks perfectly fine to me.

Also the contrast and brightness from the front control unit knobs do not make any differecne. If I adjust one of the two pots on the small board near the neckboard (one side orange and one side black) - the brightness does boost up.
And yes when I send the video signal through I get the sound no problem.

Also underscan and 16:9 creates slight blackish wavy cloudiness around the edges but not solid borders as you would expect.

If you think the jungle IC is done for than I can start looking for a spare part but it is not easy to find as I checked last week with no success.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Sun Dec 15, 2019 11:24 am 


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So I changed the two deflection capacitors in the mainboard and also the suspecting VBLANK OUT transistor on the neckboard but it made no difference.
Since the fault is so persistant that changing caps or trans doesnt even seems to make a tiny bit of a differecne I am thinking it may be a bigger issue like a faulty flyback. I suspect the screen isn't getting enough kickstart voltage to display the picture as when I switch it on it does make a sound but its not as loud as I think it should be. It sounds more like a CRT switch off sound then the loud honkish sound you hear when a CRT is switched on.

I made a short youtube video of the the dimly lit screen with raster and also the colour splash when the TV is switched off.

https://www.youtube.com/watch?v=fyT44152v-c

Maybe the colour splash is indicative of a specific fault.

Also I think I asked before as well - would you expect to see this colour splash at switch off if lets says only the jungle IC was faulty? Also would a bad jungle IC give you a dimly lit screen with faint raster?

I just want to try and get to the source of the issue and rule out potential components that may not be causing it.

Thanks


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 16, 2019 4:29 am 



Joined: 25 Nov 2019
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Well something is off. If underscan produces a cloudy image, then it sounds like its blanking indeed. The NEC processor I believe stores the values. We need to find out how to reset the value of the vertical blanking circuit.

The monitor should increase in brightness when the brightness pot is increased on the front panel. Does any input increase brightness? Try Line B.

When you changes the value, was it in the V BLANKING <60>? This is the blanking circuit for 60 HZ signals.


Last edited by freakaftr8 on Mon Dec 16, 2019 4:35 am, edited 1 time in total.

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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 16, 2019 4:33 am 



Joined: 25 Nov 2019
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Ok try this. Bring the monitor into service mode. (Menu button then release. then press and hold select/enter button and degauss at the time.

Now hold down the select/enter button for 10 seconds then release. then press + button and release, then press degauss twice.

Power off monitor and power on. (This should reset the factory flag to defaults)


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Mon Dec 16, 2019 12:34 pm 


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Yes it was VBLANKING <60> I changed before all went south. Mind you it stayed fine for about ten seconds and then puff!!
and the front knobs do not have any affect on the brightness regardless of the input source. Only the pot on the small orange/black board near the neckboard changed the brightness.

I have tried the factory resetting/setting method mentioned in the PVM-14M4 manual and I think it was something like press Menu and while Menu is displayed Press Enter + Degauss. Then press the DEGAUSS key for a few seconds (which changes the status from Write to Factory Reset) and then press the DEGAUSS key again to perfrom the reset. There is another variant of using the Blue Only B/0 key instead or DEGAUSS and I have tried that too. In fact these were the first things I tried when I faced the issue.

Your reset method is new to me. And I havent seen this in the manual at all.
But I will definitely give it a go once I get home. I have faint hopes of it making any differecne.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Tue Dec 17, 2019 1:58 am 


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Hi. Tried the reset method a few times but unfortunately no luck.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Wed Dec 18, 2019 7:48 pm 



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Well it was worth a try. That method I told you would cursor yo the factory flag defaults. I'm thinking the eeprom is screwed or it may be something completely different from an issue with V blanking altogether. it's not putting out video. Or the video and V/H signals are not getting processed. there is a big NEC IC on the board. This I believe holds those settings. look st the IC, download the PDF, and find a pinout for the SDA and SCL if it has those callouts. they may have to be shorted to ground to reset the ID's and settings. This would be a last resort though as it would reset all settings in the monitor may look horrible if it comes up.

For now the only thing that we can do is scope the output wave forms while you switch between inputs to see if any video is coming out or what that jungle IC is doing


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Fri Dec 20, 2019 7:09 pm 



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At this point, I'd try replacing the failing capacitors around the geometry circuit since we know they are flakey. you never know, maybe that will straighten out the picture enough to get it back on track. it's worth a try.


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Sat Dec 21, 2019 12:42 am 


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Thanks. These are all valid points. And I have replaced the two capacitors that may have been causing the original RGB lines to appear but nothing has changed.
I have changed transistors on the neckboard too. After all that I would have expected at least something to change. Even if its very bad geometry

I am really beginning to suspect that the flyback has some issue. When turning on the monitor, there just isn't enough noise to deduce that the tube is getting its 28kV acceleration voltage and its all too quiet. Also I am not seeing any bright white light when switching it off either and just faint colours which we agreed wasn't normal. Its persistantly staying very dim no matter what I do.

I Googled around and one of the close matchecs was CRT with very dim barely visible picture troubleshooting. The cause was said to be the base socket on the neckboard ( the white plastickybit that attached to the tube) and that it wasn't getting correct G2 voltage to pass on to the tube. There are a few wires going into the base socket but two of these are focus Red and focus Black wires from the small orange focus board and the third wire is from the neckboard itself. I think the G2 voltage in on the 5-pin connector that attahces the neckboard to the mainboard and the neckboard is providing the G2 voltage to the socket using internal circuitary. I have measured the G2 voltage on the 5-pin connector while the mnitor was on and its was giving 1200 volts. Also one of the nine or ten pins of the base socket that attaches to tube also has a G2 pin and that was giving 184V. The repair guy said that if the G2 voltage isnt the issue then probably your flyback transformer has some fault.

Not sure of if there is a safe way of checking whether the flyback is indeed providing the kickstart 28KV voltage to fire up the tube or not?


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Wed Dec 25, 2019 4:33 pm 


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Try contacting this guy from Tennessee. His name is Steve, he has a Youtube channel as well he might be of some help.

https://www.youtube.com/channel/UCwOTvO ... x1PCrfmTKw


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 Post subject: Re: Sony PVM 14M4 - No display after tweaking Service Menu
PostPosted: Fri Dec 27, 2019 4:24 pm 


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zionfarm wrote:
Try contacting this guy from Tennessee. His name is Steve, he has a Youtube channel as well he might be of some help.

https://www.youtube.com/channel/UCwOTvO ... x1PCrfmTKw


Thanks Zionfarm.
I had left a few comments on some of his PVM restore videos but there have been no replies.
I will try again and see if there is another way to get in touch with him.

Thanks


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