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 Post subject: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Tue Oct 20, 2020 9:28 pm 


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Joined: 04 Oct 2020
Posts: 22
Location: London
Hello,

I got hold of Sony BVM 14G5E at an auction of a broadcast studio that was closing down. These auction can be a bit of a gamble. I guess I got a bit unlucky with this one: The BVM has 149,761 hours (that's 17 years!) of flight and according to a sticker on the back the tube was replaced in Feb 2007.

To my surprise the caps looked in very good shape and had no sign of having been replaced or having leaked. I checked the power supply module, the deflector board and the neck board.

After a couple of minutes of turning the monitor ON and using it it overloads: https://www.youtube.com/watch?v=xL3Vwqdcbxc
On the plus side, the image seemed fine and there is no image burnt into the tube.

I though it would be worth trying recapping G, E and D boards, hopefully this would fix the overload issue.
102 caps later: I tried turning the beast back on and it now exhibits strange symptoms: the tube draws an extremely "zoomed up" image, to the point you only see around 12 lines at a weird angle plus and oblique one (the return of the electrons beam?).
There is also a weird low frequency brightness oscillation: https://www.youtube.com/watch?v=nafXPEzFSrs

It's not in a very happy place right now.

I have already double checked all the caps were inserted the with the right polarity and that the values are correct...
When I have a couple of hours ahead of me, I'll check again and also inspect all solder joints to see if I shorted anything...

If those symptoms ring any bells to anyone, please let me know your thoughts!

I'll update this thread if I make any progress.

Thanks!


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Wed Oct 21, 2020 2:48 am 



Joined: 03 Mar 2005
Posts: 475
Just throwing out a thought:

Do you think it's possible that you removed a cap but forgot to replace it? In addition to shorts, that's something I'd look for.


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Tue Feb 23, 2021 9:10 am 


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Joined: 04 Oct 2020
Posts: 22
Location: London
It turns out while recapping I must have applied pressure on a surface mount resistor with the tip of my soldering iron and snapped it, breaking a circuit controlling the yoke (hence the very spacing between each line on displayed on the tube).

The resistor in question was R034. I managed to salvage a similar resistor from a donor board and now that issue is solved.

The next issue is the image was very noisy for a few minutes, then once "warmed up" the image would become clean.

This took me a while to sort out. It took a phone conversation with "savon pat" to put me in the right direction...

I knew it was something with BK (the input board that takes RGB + sync and connects to the neck board) since I had a spare one from another BVM of the same range...

Patrick recommended I get an ESR meter to check the surface mount resistors on that board. Turns out most resistors will probably need replacing as they mostly all test to have high ESR.
A few around the voltage regulators failed the test completely or had a really really high ESR (8 Ohm and more). I replaced those three and now the image is no longer noisy when the monitor is "cold"!

Hope this helps.


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Tue Feb 23, 2021 11:53 am 


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Joined: 16 Jan 2014
Posts: 1564
Curious as to why you would use an ESR meter (used for capacitive/inductive ESR measurement) on a resistor. That doesnt make sense- a resistors "ESR" will never be higher than its actual DC resistance.


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Wed Mar 10, 2021 9:12 pm 


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Joined: 04 Oct 2020
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Location: London
Josh128 wrote:
Curious as to why you would use an ESR meter (used for capacitive/inductive ESR measurement) on a resistor. That doesnt make sense- a resistors "ESR" will never be higher than its actual DC resistance.


You wouldn't I completely agree with you. There is no point testing a resistor with an ESR meter, it's to test caps!

Apologies if my previous post was confusing.

The first issue I had (spaced out lines on the CRT) after recapping was caused by a broken SMD resistor on the E board.

After fixing that, I wanted to find what was causing the image to be noisy for a few minutes until the monitor warms up. I discussed this with savonpat and he said it's probably a bad cap somewhere else and added that having a ESR meter (to test caps) is very helpful to quickly find which caps may be suspicious or bad.


Last edited by bounav on Wed Mar 10, 2021 9:24 pm, edited 1 time in total.

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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Wed Mar 10, 2021 9:23 pm 


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Joined: 04 Oct 2020
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Time for an update.

Using my ESR meter I found that a lot of caps on the input board (BK board) had suspicious SMD caps. A few caps around the voltage regulaters would not even test on the ESR meter or test with really a high ESR (15 Ohms or more).

After replacing those caps (the really bad ones near the voltage regulators), the fuzzy image issue when the monitor is cold has disappeared.

All is well!... not quite.

I reset everything to factory default and now the monitor seems to think it's without built in controls on each side of the CRT. This means when I press keys I don't get the expected behaviour.

For example:
    - "DEL" triggers "1" (handy to know if you need to input the maintenance password!)
    - "SHIFT" triggers "ADDRESS"
    - the menu, enter, up and down seem to be rotated 90 degrees

When I connect a "remote" unit (BKM-10R) straight to the connector 8 on the TB board it works fine.

So what I'm getting from the built in control is the mapping of BKM-10R external remote!!! As if the computer board was thinking it's a 20" BVM without built in controls.

Quite annoying. I'm going to go back to the service manual to find if there isn't an setting for this somewhere...


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Sat Mar 20, 2021 3:53 am 


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Joined: 04 Oct 2020
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Location: London
bounav wrote:

So what I'm getting from the built in control is the mapping of BKM-10R external remote!!! As if the computer board was thinking it's a 20" BVM without built in controls.



I checked the status menu of the BVM and it reports it is a 20G1U, with a serial number of only zeros and the operation time got reset to zero hours as well.

The model number I think explains why the button are not mapped correctly.

Anyone familiar with BVM firmware here that could help change the model/device ID and change the serial number?


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Mon Mar 22, 2021 3:01 pm 



Joined: 07 Aug 2018
Posts: 71
bounav wrote:
I checked the status menu of the BVM and it reports it is a 20G1U, with a serial number of only zeros and the operation time got reset to zero hours as well.

The model number I think explains why the button are not mapped correctly.

Anyone familiar with BVM firmware here that could help change the model/device ID and change the serial number?


Can you check the voltage of the coin cell battery on the ISR board? It seems it might be dead as these settings are saved in the SRAM.


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 Post subject: Re: Sony BVM 14G5E with 149,761+ hours needs some TLC
PostPosted: Wed Jun 09, 2021 4:11 am 


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Joined: 04 Oct 2020
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Location: London
ElBartoME wrote:
bounav wrote:
I checked the status menu of the BVM and it reports it is a 20G1U, with a serial number of only zeros and the operation time got reset to zero hours as well.

The model number I think explains why the button are not mapped correctly.

Anyone familiar with BVM firmware here that could help change the model/device ID and change the serial number?


Can you check the voltage of the coin cell battery on the ISR board? It seems it might be dead as these settings are saved in the SRAM.


Checking the battery is indeed the first thing anyone should do. Mine still gives 3V out ;).

Pro tip: If you check the battery do it without removing it!!!


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