Sony KV-XJ29M31 Picture power on delay issue

[Dreamcazman]

Hi all, I've recently got back into some retro gaming & after reading about RGB modding I just had to do it for myself.

I picked up a Sony KV-XJ29M31 cheaply through FB marketplace & completed the mod without an issue, however, I have another problem which I hope someone can help me with or at least steer me in the right direction.

Basically, the issue is when it's cold, it takes a while (like over a minute) for the picture to come up. I can hear the degaussing sound & I can change inputs & hear audio but just a blank screen. Once it's up & I've used it a little bit, I can turn it off then back on again shortly after & the picture comes up quickly. Any ideas?

The service manual doesn't mention this specific problem, but I assume it may be a capacitor issue or something that needs to warm up and/or charge first.

I'm relatively knowledgeable with electronics, but I'm a little rusty as I haven't worked on CRT's for a long time. I'm sure someone here is more expert than me.

Any help would be greatly appreciated.

[Dreamcazman]

Ok after some testing I found that if I turn the TV off using the remote (ie standby), the picture comes up straight away when I turn it back on.

So this just may be normal for this TV, I'm not sure.

I do however have another issue regarding the RGB mod, but I suspect it's better to be asked in the RGB mod thread (link below).

viewtopic.php?f=6&t=56155&p=1484612#p1484612

[MarkOZLAD]

A minute to turn on seems excessive.

Maybe try leaving the TV running for an hour or so, see if the capacitors reform.

[Dreamcazman]

A minute to turn on seems excessive.

Maybe try leaving the TV running for an hour or so, see if the capacitors reform.

Thanks, I fixed up the RGB mux mod that you helped me with, but it's still doing the dark picture thing. Incidentally, when I turned it on after doing the mod, I actually got a picture, but it was darker than before (with the mod done wrong). I initially thought the mod fix didn't work, but then all of a sudden, bam the picture really came in & was super bright.

However after a few minutes, it went dark again for a second, then came back to good. It's been around 10mins now & hasn't played up. I'm really suspecting a dodgy cap now, but which one?

I'll leave it running for an hour or so & hopefully it improves.

[MarkOZLAD]

I'd be looking at C565 and C558 first.

[Dreamcazman]

I'd be looking at C565 and C558 first.

Ok, thanks. I'll test those & see if they're ok.

Had a quick look online & if I do need to replace them, nowhere seems to have local stock. Anywhere you recommend besides Aliexpress?

[MarkOZLAD]

I'd be looking at C565 and C558 first.

Ok, thanks. I'll test those & see if they're ok.

Had a quick look online & if I do need to replace them, nowhere seems to have local stock. Anywhere you recommend besides Aliexpress?

RS Components

[Dreamcazman]

Ok, so I pulled the two caps out...

C558 is 33uF 160v - measured as 38.3uF
C565 is 47uF 250v - measured as 47.7uF

I also tried the resistance method & they measure OL most of the time.

Going by that, I think it's safe to say the 33uF cap is kaput - agree Mark? I might replace both though to be safe.

Funny that, the 47uF cap is a Rubicon, the dead one is a no-name brand, lol.

EDIT: Actually, 38.3uF is within tolerance so I'm not so sure now... I wish I could just buy one each of these locally to try instead of spending close to $35 to get some shipped from RS.

EDIT: I found a local components supplier where I can buy these, so will try them first.

[Dreamcazman]

I picked up the replacement caps & swapped them over, the delay is still there.

Having said that, it doesn't seem to be as long. I didn't time it, but I'm sure it's less than a minute now.

I will time it the next time I turn it on.

[MarkOZLAD]

I picked up the replacement caps & swapped them over, the delay is still there.

Having said that, it doesn't seem to be as long. I didn't time it, but I'm sure it's less than a minute now.

I will time it the next time I turn it on.

I was thinking about the dimming issue, not the turn on time, when I recommended those caps.

[Dreamcazman]

I was thinking about the dimming issue, not the turn on time, when I recommended those caps.

Sorry, I'm a little confused. The dimming issue is part of the turn on time.

Ok, I had it off for the last few hours & have just tried it (timing it this time). I turn the TV on & after 10 secs the blue screen comes on with 'Video 1' in the top corner but it's very dark. When it hit 35 secs, the brightness came in & everything seemed normal.

So it seems replacing those caps has helped somewhat. Before I wasn't even getting the initial blue screen plus it was taking a lot longer.

I can make a video if it helps.

[MarkOZLAD]

Is the dimming issue only in RGB mode?

[Dreamcazman]

Is the dimming issue only in RGB mode?

Not that I've noticed, it does it whatever the input is.

I wondered whether it may have been mod related or not. The problem is I only briefly tested the TV after I got it so I don't know if it was doing this previously.

I will ensure the blanking switch is off and/or disconnect the RGB lines & see if it makes a difference.

[Dreamcazman]

Update: I've discovered something interesting. I had the blanking switch off & turned the TV on, made no difference. Then I left if off for a couple of hours & in that time, I unclipped the vero board (like in the photo) which effectively removes the RGB mod & I get a normally bright image now when I turn the TV on.



I'm not sure what's going on, unless it's something to do with the different resistor values. I will do some more testing to make sure I can continually replicate it.

[MarkOZLAD]

Can you describe your blanking circuit?

[Dreamcazman]

Can you describe your blanking circuit?

5V (from IC100) - switch - 470ohm - teletext header

[Dreamcazman]

I've been testing the TV periodically throughout the day, leaving it a fair few hours in between. So atm the only difference in the way it is currently compared to stock is that the 470 ohm RGB grounding resistors have been removed from the underside of the board.

Turning the TV on, comes up with a seemingly normal blue screen, then the intensity seems to ramp up a little after 1-2 minutes & the OSD is a little blurry. I suspect that's due to either the missing resistors or the teletext board.

To recap, on turn on:

With the mod, the screen is dull, then goes normal.
Without the mod, the screen is normal, then goes a little overbright.

Very weird, I hope that makes sense.

I tried taking a video, but capturing it using a phone is rather difficult.

[MarkOZLAD]

The nature of the mod is that the resistors have been moved, not removed.

[Dreamcazman]

I reinstalled the mod for now so I can at least use the RGB.

I could leave it as is & put up with the delayed start but it annoys me not knowing what's causing it. I'm sure it's a cap somewhere that's dodgy so I'll pick up an ESR meter (which I was thinking of doing anyways) & test the caps.

[Dreamcazman]

Just a quick update:

I got my ESR meter & found around a dozen caps that were out of spec on the mainboard, most of which were next to transistor heatsinks. I replaced those but it didn't fix the power on delay.

So basically the TV is as it originally was before I replaced the caps. Not sure what else it could be & with my limited knowledge/tools to troubleshoot, I may just leave it as-is, at least I can still use it.

[VEGETA]

I have a question for you which is off topic, sorry.

I have xj29m80 offered to me but without remote.

if this model of yours is similar, can you check if you can choose video source from tv buttons? like composite, s-video, and component (especially component). please try it.

on a side note, how good of quality can this be? assuming component output and about 3 meters away sitting.

[Dreamcazman]

I have a question for you which is off topic, sorry.

I have xj29m80 offered to me but without remote.

if this model of yours is similar, can you check if you can choose video source from tv buttons? like composite, s-video, and component (especially component). please try it.

on a side note, how good of quality can this be? assuming component output and about 3 meters away sitting.

Yes, you can change inputs without a remote, there is a button on the front of the TV next to the volume controls. I didn't get a remote with my set either, but if you do need one for service menu, etc, any Sony remote will work as they all use the same coding.

The picture quality of the TV is very good.

[VEGETA]

I have a question for you which is off topic, sorry.

I have xj29m80 offered to me but without remote.

if this model of yours is similar, can you check if you can choose video source from tv buttons? like composite, s-video, and component (especially component). please try it.

on a side note, how good of quality can this be? assuming component output and about 3 meters away sitting.

Yes, you can change inputs without a remote, there is a button on the front of the TV next to the volume controls. I didn't get a remote with my set either, but if you do need one for service menu, etc, any Sony remote will work as they all use the same coding.

The picture quality of the TV is very good.

hello

thanks for your advise.

can you kindly send high quality pictures of it showing some games?

also, which button changes input video source?

actually, what various sources are available?

thanks

[Dreamcazman]

hello

thanks for your advise.

can you kindly send high quality pictures of it showing some games?

also, which button changes input video source?

actually, what various sources are available?

thanks

I have taken a photo of Sonic here viewtopic.php?f=6&t=56155&start=4290
The input changes the source. You see on the photo the five grey buttons, the input is the one on the far left.
On my TV, there are two composite, Video 1, Video 2 then DVD (component).