Nanao 2930 - no screen with neck glow

[JSN_]

Hi Guys,

A lot of you chimed in on my last post about having a blue screen which @GeekMan1222 was able to resolve.

It was fixed (bad neckboard transistor), recapped and tested working and shipped back to me, now I’m getting nothing on the screen. Before I take any more steps I wanted to consult the masses on any potential things to check.

i can upload a video shortly if that is helpful. But basically the screen just is off with neckglow and power to everything else in the cab.

 

[advans14]

check your video connections and the dips on the remote board. what board are you using? do all of this with the game off.

 

[JSN_]

Video connections i’ll check again but I’m pretty confident in them.

Dips are definitely alright as it was working before and I hadn’t touched them.

It’s running a mistercade right now (mister with jamma edge)

 

[GeekMan1222]

You still hear the horizontal deflection humming as well with the neck glow right?

It could very well be something simple though.

Rule out the simple things which is what you have been doing.

Some ideas: use a different device to drive video to the monitor as well. Maybe something with VGA if you have a Naomi?
Try a different remote board if you had another.
Reseat all connectors on the chassis and RGB signal cables in the cabinet.
If you had a second blast or something you could potentially swap the chassis's and see if the problem follows the chassis then you 100% ruled out the chassis more or less.

---------------

If it helps anyone else out here with suggestions or ideas hears a quick break down from my understandings.

My understanding of these chassis is that theres 3 major blocks if you will. Theres a deflection block and a B+ block and your HV block.
If your B+ block (I adjusted the B+ last and its a solid 180V, you could check this again if needed) is running then neck glow will be present along with other things getting the B+ they need.
If the horizontal is running well then you would hear that deflection running (not sure how to describe it you know it when you hear it running)
Then your HV is its own thing which supplies your 29~ KV of voltage to the tube anode it will get some some voltage from the B+ as well but its regulated through this block first.
The HV block as a whole is its own stand alone circuit mostly, unlike older chassis's. You have a HV generation circuit which consists of the Murata HV controller IC on the little daughter board, then a high speed mosfet for controlling the flyback transformer and thats about it.

The interesting thing is the HV control IC also handles some protection things. So it checks for xray protection by checking some voltages, it checks for pulses in the deflection circuits and it checks for the HV output for safety checking and regulation of the HV using the mosfet.

The curious thing to me is if it has neck glow and the deflection is running then why is there no HV? Is the mosfet bad is there something in HV block that is bad or wrong or has a bad solder?
Maybe the HV or Xray protection needs tweaking? I get really nervous ever wanting to touch the HV adjust pot or Xray protection because these are a little fiddly and important adjustments.

Hopefully someone really smart or clever has good suggestions on this ?

Without a High Voltage probe you cant measure the anode when the chassis starts. It could be spiking the voltage and shutting the HV down or just not have any voltage period on start up or it could be excessively low. Any of these things will cause you not to have raster (image)

Worse case scenario is the flyback is weak or bad or the murata controller IC is bad.

Considering how this chassis was just running recently idk if this is the case. The HV output on the anode when I tested was a little low almost 28KV but since it was running fine during burn in tests I didnt want to disturb the setting at all.

I already told JSN I could take another look at it or offer an exchange if hes gives up on it but without knowing more my self and spending hours trying to learn more about the HV block I would need alot more time than I may have coming up for this kind of work. JSN wants to take a stab at this him self and getting down and dirty is a good way to learn things so more power to him.

 

[Metal Slug]

Do you feel static on the front of the screen when you turn it on? Have you tried turning up the flyback screen knob, do you see raster lines?

 

[JSN_]

Do you feel static on the front of the screen when you turn it on? Have you tried turning up the flyback screen knob, do you see raster lines?

I’ll give it a go with turning up the knob a few times tomorrow. Haven’t had much time today.

I definitely hear the deflection hum from the chassis as geekman described.

As far as static I don’t see or hear any kind of screen static that you would with a CRT. I’m almost 40 so I’m well familiar with that screen static haha.

This may sound noobish and it probably is, but connecting the Anode cup to the screen… is there a trick here?

Sometimes i can just lightly place it into the socket and it sticks, but am I supposed to pinch those prongs together and make sure it’s all the way in? Or should it just sort of “catch”.. if you’ve done this before you probably understand what I mean.

I’ll post a vid in the AM.

Would testing this in TATE mode have any bearing whatsoever?

 

[rewrite]

but am I supposed to pinch those prongs together and make sure it’s all the way in?

Yes.

Best way is flip the suction cup partially inside-out, put in one of the two prongs, push it sideways until the other prong gets inside the hole as well, then let the suction cup flop back where it belongs.

Would testing this in TATE mode have any bearing whatsoever?

Nope.

 

[Metal Slug]

I’ll give it a go with turning up the knob a few times tomorrow. Haven’t had much time today.

I have received chassis that when I first connected to a tube they appeared non-functioning, but only required an adjustment of the flyback to bring the image up. (Just in case, the flyback is the large black plastic part on the chassis that has the red wire and anode cap connected to it, there are 2 knobs on it a focus and a screen knob, adjust the screen knob and you should see raster lines even without a signal when it is set too bright.)

 

[GeekMan1222]

yeah check the screen voltage it maybe low for your set?
And as rewrite said the best way so long as the set is off and all that is to flip the anodes cup back and clip it in that way to visually see it clip in. Then let it flop back. This will also lets the rubber cup seat better to the tube like if you just pushed it on sometimes the edges of the cup will flare out and stay out for instance.

 

[advans14]

Make sure you discharge that tube before you screw with the anode cup obviously. But yeah, i just ran into this the other day and as most collectors know. No picture, but neck glow = no hv. Youd hear the “crackle” and static sound when flipping the power on. Touch the face of the tube etc and feel the static etc.

Possibilities are hv shutdown, which is sometimes triggered by sync protection. If you have a wrong dip flipped and plug in a board. You will hear the squeal and monitor will shutdown. It will usually not come back on for about 3 minutes and you can actually hear an audible sound “click” when its ready to come back.

I think a good video would help. Even with the flyback turned down youd still get the static warm up. Could be a fuse. Is this tested out of cab?

 

[JSN_]

View: https://youtu.be/QVxwVvYyYTw


Here’s a visual rundown of what’s happening

Here’s also a pic of the neck which you couldn’t really see in the video.

 

[advans14]

On your tube frame front where is your wiring. If the circled is not plugged
In the video could have issues.

 

[JSN_]

This is all I have on the front. All plugged in. Not sure what the empty cutout is for

 

[TodoRojo]

To preface, I highly doubt this is the issue; but the neckbeard might be able to sit down a little bit further. Of course, be careful. Don't want to neck the thing. Just looks like there's a bit of space there if you haven't already tried ¯\_(ツ)_/¯.

A couple other things come to mind: 1) do you have another board aside from your Mistercade? If the ini file is corrupt or something maybe that is the actual issue. I'd try a different board if you have the ability. 2) have you adjusted the screen pot on the flyback at all? If you do touch this, you'll need to readjust it later fyi. Maybe it'll at least show some raster lines.

 

[JSN_]

To preface, I highly doubt this is the issue; but the neckbeard might be able to sit down a little bit further. Of course, be careful. Don't want to neck the thing. Just looks like there's a bit of space there if you haven't already tried ¯\_(ツ)_/¯.

A couple other things come to mind: 1) do you have another board aside from your Mistercade? If the ini file is corrupt or something maybe that is the actual issue. I'd try a different board if you have the ability. 2) have you adjusted the screen pot on the flyback at all? If you do touch this, you'll need to readjust it later fyi. Maybe it'll at least show some raster lines.

I’ll double check my ini, I’m fairly certain its good though.

Will give this a tighter fit as well.

 

[TodoRojo]

I’ll double check my ini, I’m fairly certain its good though.

Will give this a tighter fit as well.

Yeah I'd bet it's fine; but it can't hurt to double check. Maybe just grab the default one from MisterAddon's GitHub to try out. Hopefully this gets resolved soon!

edit: I'm just realizing my original post autocorrected neckboard to neckbeard and I'm not changing it, lmao.

 

[advans14]

Yeah I'd bet it's fine; but it can't hurt to double check. Maybe just grab the default one from MisterAddon's GitHub to try out. Hopefully this gets resolved soon!

edit: I'm just realizing my original post autocorrected neckboard to neckbeard and I'm not changing it, lmao.

Lol my autocorrect does that too

 

[JSN_]

Lol my autocorrect does that too

We’ve all got a little neckbeard in us

 

[JSN_]

I think a good video would help. Even with the flyback turned down youd still get the static warm up. Could be a fuse. Is this tested out of cab?

I just remembered your comment about a fuse. I see the 2 glass fuses and they’re both still good. are there any others on the chassis?

 

[advans14]

Always. Also check your cab interlocks