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jcmorrisii

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Hello friends, sadly my Windy is suffering from vertical collapse. I know these PB6643-1 are prone to failure and eating HOTS but damn if it wasn't an amazing picture when working right! After powering on, the screen would increasing shrink as it continued to warm up. After 30min or so the screen would hold at a very small size and shake horribly when any explosions happened on screen etc.

So I have replaced every electrolytic capacitor on board (including filter cap) and the Vertical IC and HOT (LA7838 and C5143 respectively). Nothing looks suspect, no lifted pad/cut traces etc. There are hot spots on board where the vertical and HOT sections are (darker color PCB from heat).

Now When I power on, there is nothing but a single small vertical line going up the center of the screen (Tate ). :unsure:

So I thought, well maybe one of the "new" ICs was bad so I put back in the original LA7838, test, same issue. I then replace the original HOT, test, same issue occurs :(

Now Im at a loss, and hoping someone can provide some input as to why I am now suffering full vertical collapse and where to go from here?
I have some spare Nanao MS9s I could splice in if I had the right yoke connectors but was really hoping to save this chassis! When working it had a PERFECT picture, and this would be the second PB6643 going into a box in the closet if I cant get it running :(
 

brad808

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Have you verified the yoke and yoke connectors? If you have then it might be time to get out the old oscilloscope and get probing to see where you are losing the signal.
 

brad808

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Also go slow and follow schematic if there is one. A bunch of those things won't have anything to do with vertical collapse (things like hot, filter cap, the vast majority of caps on the board, etc). Try to narrow down and troubleshoot in the vertical section to save time and money 😎
 

jcmorrisii

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Have you verified the yoke and yoke connectors? If you have then it might be time to get out the old oscilloscope and get probing to see where you are losing the signal.
Verified how ? Checking the Ohms on connectors with a DMM? I do have a cheap oscilloscope but to be honest don’t have much if any experience in using it. Any tips on what to begin probing in the vertical section and what to look for?
Also go slow and follow schematic if there is one. A bunch of those things won't have anything to do with vertical collapse (things like hot, filter cap, the vast majority of caps on the board, etc). Try to narrow down and troubleshoot in the vertical section to save time and money

Yeah my thought was that while I was there in, I would replace old ICs early that are known to fail to sort of get ahead of the problem, but looks like it worsened it somehow (at least got Some usable image before) haha 😆 Any idea what component may be causing the issue or where I should begin?

Thanks so much for taking the time to comment.
 

brad808

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Can do these first two with the Mon off...

For yoke connector/cable it is simple - you will use continuity test of multimeter. You want bottom of chassis PCB (use solder point before final header pin if you can to fully verify) to the yoke itself. That will verify your header pins, solder, connector, cable is all good going to yoke. You want very low resistance and/or your continuity buzzer going off. You only need to check your vertical pins because your horizontal is working... Save some time and work smart 🙂.

For yoke itself - One of the best ways to verify the yoke is with a "ringer". Basically pulses a signal and reads the "rings" (echoes) to ensure no shorted or open windings in the coil. Can use the same method for other winding (like flyback, switching Transformers, etc). If you have no Ringer you can read the inductance and resistance of the coil if you have meter for that and it should give you a decent idea if something is off. Would likely need to verify those readings off a known good one if you can find the readings online.

Start with those things first then check the LA7838 vertical deflection IC using your oscilloscope.

***Do this with the Mon on but make sure you turn down the brightness so that you don't have single line running across your screen burning in***

There is a pinout on page 3 of the datasheet for the vertical IC which will be your guide for what you are looking for with your scope. Do you have power? Do you have input? Do you have output? That will hopefully get you on the right track.
 

jcmorrisii

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Can do these first two with the Mon off...

For yoke connector/cable it is simple - you will use continuity test of multimeter. You want bottom of chassis PCB (use solder point before final header pin if you can to fully verify) to the yoke itself. That will verify your header pins, solder, connector, cable is all good going to yoke. You want very low resistance and/or your continuity buzzer going off. You only need to check your vertical pins because your horizontal is working... Save some time and work smart 🙂.

For yoke itself - One of the best ways to verify the yoke is with a "ringer". Basically pulses a signal and reads the "rings" (echoes) to ensure no shorted or open windings in the coil. Can use the same method for other winding (like flyback, switching Transformers, etc). If you have no Ringer you can read the inductance and resistance of the coil if you have meter for that and it should give you a decent idea if something is off. Would likely need to verify those readings off a known good one if you can find the readings online.

Start with those things first then check the LA7838 vertical deflection IC using your oscilloscope.

***Do this with the Mon on but make sure you turn down the brightness so that you don't have single line running across your screen burning in***

There is a pinout on page 3 of the datasheet for the vertical IC which will be your guide for what you are looking for with your scope. Do you have power? Do you have input? Do you have output? That will hopefully get you on the right track.
Ok so had a chance last night to do a few of the aforementioned tests. Probing the vertical IC while powered up will be a challenge because the monitor is installed in the windy and Iv got an injured back at the moment so not going to be moving it out onto a test bench anytime soon. Maybe able to put a piece of cardboard under the chassis and turn it on its side so I can access it while it’s running .

But as far as the yoke goes.... Tested continuity between the solder points on underside of PCB and the actual yoke with no issues. Same between the Lh/Lv solder points to the LA7838, continuity positive where it should be. Read the inductance on both vert and horizontal as well; I also did have a spare windy yoke from a monitor that had been necked and I tested it with the exact same numbers(The necked windy yoke read 5.3 ohm , the only difference):

Rv: 5.1 ohm
Rh: 0.6 ohm

If anyone here with a windy can verify this is correct that would be great. Is .2-.3 something to worry about? The Rh/Rv is pretty close to the chart listed here :
A1468ECF-40FF-486C-A8B3-42DA895855F8.jpeg


So.....let’s say that for some reason the LA7838 isn’t getting enough juice to power it, do you know what component would be at fault? I haven’t found an actual schematic of the chassis that is readable . Also have a simple logic probe if you think that would be useful in any capacity.
 

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Plymelk

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RE the yoke measurements, these are analog electronics and there will some tolerable variance between each monitor to another. I can confirm that the measurements you posted are indeed close to my working Windy I Toshiba chassis measurements when I pulled it. Inductance would be a more indicative metric for testing IMO, but you said those check out and I think these posted measurements are accurate to my cab. I can confirm specific values if needed.

To my knowledge, Toshiba kept their chassis designs under lock and key, more so than any other manufacturer that I can determine, and as a result there is just no schematic information out there on this chassis or any of their other designs. You can find bits and pieces like cap lists and the like, but I do not think a schematic or parts sheet for this chassis has been scanned or ever will be. I'd love to be wrong on that.

I found that these chassis's mirror the MS9-29 in many ways (down to the compatibility between the yokes for the two). For a theory of operation I would start looking at that service manual in lieu of Toshiba's locked design. That's what I would do at least. This chassis like all others uses a numbering convention for its circuits (i.e., the C4XX, R4XX, and so own will correspond to capacitors, resistors, etc. in the horizontal circuit). I would start reflowing and checking cold joints across all components in the 300 (vertical) section of the chassis. I found that the yoke pin headers in particular needed rework when I had this chassis out for a cap kit a few months ago.

Also, is your monitor mounted horizontally or vertically? You said that there is a vertical line going up the center of the screen (Tate). I was unclear if you were referring to the vertical line running tate or if your monitor was positioned tate. If the former, you could have horizontal collapse if your monitor is positioned horizontally (Yoko).

Brad's advice is the right path. To add some specifics to this particular cab/chassis set up (i.e., testing points not viable as you know while the chassis is mounted in the cab, due to the lack of a chassis tray on the frame), it may be best to devise some testing rig (using your spare yoke) on a different tube outside of the chassis to allow you to work on this. Just my two cents, hope it helps.
 

Zepherino

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Great info here, watching the thread for future reference.

If the chassis ends up being unrepairable, at the very least it shouldn't be impossible to find a replacement. The D29CR55 was used in a ton of Bemani games, with DDR almost certainly the most common in the US. A lot of people in the DDR/ITG community who buy cabs for home use often chuck the CRT (or even the whole cab besides pads) to replace with a larger LCD due to Stepmania being the most popular game in a home arcade setting by far.

I'm personally guilty of doing this to my DDR cab as well... although I kept the CRT and placed it in a different cab.
 

jcmorrisii

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Great info here, watching the thread for future reference.

If the chassis ends up being unrepairable, at the very least it shouldn't be impossible to find a replacement. The D29CR55 was used in a ton of Bemani games, with DDR almost certainly the most common in the US. A lot of people in the DDR/ITG community who buy cabs for home use often chuck the CRT (or even the whole cab besides pads) to replace with a larger LCD due to Stepmania being the most popular game in a home arcade setting by far.

I'm personally guilty of doing this to my DDR cab as well... although I kept the CRT and placed it in a different cab.
Good line of thinking here, is there any forums for DDR enthusiasts where they sell spare parts like you mentioned? I always keep my eye out in the normal places like eBay but only see them every so often and they are usually way overpriced (2-300)
RE the yoke measurements, these are analog electronics and there will some tolerable variance between each monitor to another. I can confirm that the measurements you posted are indeed close to my working Windy I Toshiba chassis measurements when I pulled it. Inductance would be a more indicative metric for testing IMO, but you said those check out and I think these posted measurements are accurate to my cab. I can confirm specific values if needed.

To my knowledge, Toshiba kept their chassis designs under lock and key, more so than any other manufacturer that I can determine, and as a result there is just no schematic information out there on this chassis or any of their other designs. You can find bits and pieces like cap lists and the like, but I do not think a schematic or parts sheet for this chassis has been scanned or ever will be. I'd love to be wrong on that.

I found that these chassis's mirror the MS9-29 in many ways (down to the compatibility between the yokes for the two). For a theory of operation I would start looking at that service manual in lieu of Toshiba's locked design. That's what I would do at least. This chassis like all others uses a numbering convention for its circuits (i.e., the C4XX, R4XX, and so own will correspond to capacitors, resistors, etc. in the horizontal circuit). I would start reflowing and checking cold joints across all components in the 300 (vertical) section of the chassis. I found that the yoke pin headers in particular needed rework when I had this chassis out for a cap kit a few months ago.

Also, is your monitor mounted horizontally or vertically? You said that there is a vertical line going up the center of the screen (Tate). I was unclear if you were referring to the vertical line running tate or if your monitor was positioned tate. If the former, you could have horizontal collapse if your monitor is positioned horizontally (Yoko).

Brad's advice is the right path. To add some specifics to this particular cab/chassis set up (i.e., testing points not viable as you know while the chassis is mounted in the cab, due to the lack of a chassis tray on the frame), it may be best to devise some testing rig (using your spare yoke) on a different tube outside of the chassis to allow you to work on this. Just my two cents, hope it helps.
Thanks for all the advice. When I have a LOT more time available I guess I’ll be going back over it with a fine toothed comb so to speak. I really feel like it has life left if I can identify what is at fault. I keep going back to cold solder or something similar because it was working one day then vertical collapse the next. I had moved in between houses as well in that time frame, another reason I’m suspecting something like that.

Just for $h!ts and giggles I make some adapter cables and hooked up a spare nanao ms9 I had and it fired right up. So can easily rule out any yoke/tube issues . Love this cab so very much :love:
 

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jcmorrisii

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If you have Facebook, there's a few rhythm game focused groups where people list their stuff. The most active one is probably this:

https://www.facebook.com/groups/487629124643497

With how much prices exploded recently, 200-300 sadly doesn't even sound that crazy for a chassis...
Thanks for the link, maybe I can get someone I know with an account to keep an eye out for me. I tried to sign up for Facebook recently, and they flagged my account as suspicious. Reason? I refused to provide my cell phone number 8|

Yeah I might contemplate that much for a fresh ms9 (even though it sounds absurd to me, the most I spent on one years ago was 120$ and it was cherry) but not for a chassis thats known to be a pain in the ass to work on, poorly documented, and very prone to failure.
 

Plymelk

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I needed to flip the yoke windings in the Windy 1 today. Below are my yokes measurements
H: .8 ohm
V: 5.1 ohm
H: .33mh
V: 10.6mh

These seem further off than yours if the online posted reading are the standard?
 
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