Sony PVM-1954Q

[smd4420]

Hello everyone I've been following the forums for some time now and noticed many members use Sony PVM's as their main monitor. With that I also noticed many members have advanced knowledge of electronics and I was hoping some of them might be able to provide some advice on a problem I have. I recently bought a PVM-1954Q on ebay for a very good price but unfortunately it was damaged in shipping. The back of the monitor was punched in and when the monitor is turned on the screen slowly goes from black to very very bright orange (hurts the eyes) then blacks out. I removed the cover to check for damage and saw the circuit board on the back of the tube has a massive crack in it breaking many traces. The board looks modular and I was curious of it is replaceable. Below is an image of the damage and a video of the broken behavior.



[yt]DwKJmR8A-Sw[/yt]

https://www.youtube.com/watch?v=DwKJmR8A-Sw (if the embed code above doesnt work)

Thanks in advance for any help/advice

[QXC]

I wouldn't turn it on again until you get the board replaced. You should be able to source a new board and stick it in, but some other stuff might be damaged as well. I'm no expert, but you're definately damaging the tube every time you turn it on like that.

[Ed Oscuro]

Yeah, definitely. I've not got any special insights or experience in terms of diagnosing this, but a couple things jump out: First, the lines that appear before the screen hits full brightness are retrace lines, which typically means (but perhaps not this time) that the vertical section electrolytic capacitors are bad, or the neckboard as suggested here which seems more likely. Additionally the 11.17 section (red/blue/green full on) could apply too. With luck, all the problems are related to the cracked neckboard, but keep in mind we've got no confirmation yet the blue gun is still working - it's safe to say that the red and green guns are working, though, given the orange color. Look carefully for damage to other components.

The fact it gets so bright and then cuts out also suggests to me that voltage levels are ramping up like crazy. It might not actually be damaging anything, but it's best to be safe - I'd guess the set's automatic radiation / voltage limiting circuit is cutting the power because to run it any longer or higher could burn something out and/or start to irradiate you. (Sitting in front of it, as you were, is actually the safest place to be.) As noted in the second link above, perhaps there's a short involved along with the broken (open) circuits.

I have seen sets that tend to fade in a certain color on initial powerup before fading out to black - that should be fairly normal, but in my PVM's case it's a kind of reddish color and purple before black, instead of the orange seen here (which is full red + some green with no or very little blue).

For replacing the neckboard - well, you don't know anybody who'd design and build a PCB replacement, would you? I think some user here had success fixing up a broken neckboard with glue and soldering, but I'd really not feel comfortable about doing that.

Can you possibly get better images of the neckboard?

[QXC]

First, the lines that appear before the screen hits full brightness are retrace lines, which typically means (but perhaps not this time) that the vertical section electrolytic capacitors are bad, or the neckboard as suggested here which seems more likely.

I've seen lines like that on consumer sets when the gain on the flyback is turned up too high. The set worked fine, you'd only see them if there was way too much power going to the tube.

[Xan]

I have seen sets that tend to fade in a certain color on initial powerup before fading out to black - that should be fairly normal, but in my PVM's case it's a kind of reddish color and purple before black, instead of the orange seen here (which is full red + some green with no or very little blue).

I've seen this on a 14M4E, and while I haven't checked if it's related to ACC or some other setting, I don't think it's necessarily normal as in, normal for a set in good condition. This can hint at a color imbalance, particularily noticeable in the lower IRE ranges, and that in turn might be related to uneven gun wear or weak capacitors. That set had a quite strong green tint so I tried reducing green bias as a cheap fix, which caused it to turn on with a strong purple bias which would eventually shift to grey and then again greenish after 10-15 minutes of operation.

[Ed Oscuro]

First, the lines that appear before the screen hits full brightness are retrace lines, which typically means (but perhaps not this time) that the vertical section electrolytic capacitors are bad, or the neckboard as suggested here which seems more likely.

I've seen lines like that on consumer sets when the gain on the flyback is turned up too high. The set worked fine, you'd only see them if there was way too much power going to the tube.

Looking at sources again, that looks like a much better diagnosis. Retrace lines seem related to the horizontal, including the flyback transformer, not the vertical section. Whoops.

There's an interesting additional possible or partial diagnosis given here:

RGB Supply too low –On the other hand if the supply to the RBG amplifier is low also usually causes retrace line on the screen and the screen will also be very bright. If this voltage is low it could point to the filter capacitor for that line being faulty(please confirm or replace it directly)

_________

I have seen sets that tend to fade in a certain color on initial powerup before fading out to black - that should be fairly normal, but in my PVM's case it's a kind of reddish color and purple before black, instead of the orange seen here (which is full red + some green with no or very little blue).

I've seen this on a 14M4E, and while I haven't checked if it's related to ACC or some other setting, I don't think it's necessarily normal as in, normal for a set in good condition. This can hint at a color imbalance, particularily noticeable in the lower IRE ranges, and that in turn might be related to uneven gun wear or weak capacitors. That set had a quite strong green tint so I tried reducing green bias as a cheap fix, which caused it to turn on with a strong purple bias which would eventually shift to grey and then again greenish after 10-15 minutes of operation.

I'll agree that this is the only place I've seen it, as elsewhere you get a brief gray flash, as memory serves, if there's any CRT activity before the initial startup period at all. I'm not actually sure we're talking about the same symptoms, because your other comments describe sets with notable bad symptoms - on the other hand, this CRT's operation is totally solid besides this rather strange startup behavior. Black is truly black (especially after I changed an unrelated setting - will have a look at my notes to see what it was, but it pulled down a tiny bit of gray glow across the screen). The reddish/purple color isn't very bright, and after it's faded - I think it's only visible for a second or so - the CRT stabilizes rapidly (seconds, if that) and operation is appears totally normal from that point on, with good color balance.

[smd4420]

Thanks for all the replies. This is very helpful information.

Yeah, definitely. I've not got any special insights or experience in terms of diagnosing this, but a couple things jump out: First, the lines that appear before the screen hits full brightness are retrace lines, which typically means (but perhaps not this time) that the vertical section electrolytic capacitors are bad, or the neckboard as suggested here which seems more likely. Additionally the 11.17 section (red/blue/green full on) could apply too. With luck, all the problems are related to the cracked neckboard, but keep in mind we've got no confirmation yet the blue gun is still working - it's safe to say that the red and green guns are working, though, given the orange color. Look carefully for damage to other components.

The fact it gets so bright and then cuts out also suggests to me that voltage levels are ramping up like crazy. It might not actually be damaging anything, but it's best to be safe - I'd guess the set's automatic radiation / voltage limiting circuit is cutting the power because to run it any longer or higher could burn something out and/or start to irradiate you. (Sitting in front of it, as you were, is actually the safest place to be.) As noted in the second link above, perhaps there's a short involved along with the broken (open) circuits.

I have seen sets that tend to fade in a certain color on initial powerup before fading out to black - that should be fairly normal, but in my PVM's case it's a kind of reddish color and purple before black, instead of the orange seen here (which is full red + some green with no or very little blue).

For replacing the neckboard - well, you don't know anybody who'd design and build a PCB replacement, would you? I think some user here had success fixing up a broken neckboard with glue and soldering, but I'd really not feel comfortable about doing that.

Can you possibly get better images of the neckboard?
Yeah, definitely. I've not got any special insights or experience in terms of diagnosing this, but a couple things jump out: First, the lines that appear before the screen hits full brightness are retrace lines, which typically means (but perhaps not this time) that the vertical section electrolytic capacitors are bad, or the neckboard as suggested here which seems more likely. Additionally the 11.17 section (red/blue/green full on) could apply too. With luck, all the problems are related to the cracked neckboard, but keep in mind we've got no confirmation yet the blue gun is still working - it's safe to say that the red and green guns are working, though, given the orange color. Look carefully for damage to other components.

The fact it gets so bright and then cuts out also suggests to me that voltage levels are ramping up like crazy. It might not actually be damaging anything, but it's best to be safe - I'd guess the set's automatic radiation / voltage limiting circuit is cutting the power because to run it any longer or higher could burn something out and/or start to irradiate you. (Sitting in front of it, as you were, is actually the safest place to be.) As noted in the second link above, perhaps there's a short involved along with the broken (open) circuits.

I have seen sets that tend to fade in a certain color on initial powerup before fading out to black - that should be fairly normal, but in my PVM's case it's a kind of reddish color and purple before black, instead of the orange seen here (which is full red + some green with no or very little blue).

For replacing the neckboard - well, you don't know anybody who'd design and build a PCB replacement, would you? I think some user here had success fixing up a broken neckboard with glue and soldering, but I'd really not feel comfortable about doing that.

Can you possibly get better images of the neckboard?

I removed the neckboard last night and looked for physical damage on other components including the tube neck and all looks ok. The crack might have severed the circuit for the "blue" and dampened "green" resulting in the orange. (heavy speculation there) Searching online for parts I was able to come up with https://sony.encompass.com/item/1443467 ... C.board,_C But I have a feeling they are just going to say its out of production.

Thanks for the link that website tones of good information that can help me out a lot.

I'll upload better pictures of the board tonight when I get off of work.

[smd4420]

Here are some more detailed pics and you should be able to click them now for full resolution