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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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Joined: 11 Nov 2019
Posts: 11
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: 12
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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Joined: 11 Nov 2019
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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
Posts: 12
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: 12
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
Posts: 12
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: 12
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
Posts: 12
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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