SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

[laughatthemall]

Hello. I am here hoping someone might have some information on this unit. I had originally disassembled this, to recap the board. It was producing the famous 'wavy lines', which recapping I do believe did fix. However, I am not positive but I do believe I accidentally mixed up the two five-pin connectors (stupid move, I know), and that worked poorly. I say this because upon reconnecting power, a resistor violently burned (bright glow), thankfully I was watching and it only occurred for a second, but that was still (I believe) enough to cause damage. The resistor is definitely burnt, still reads about 100 ohm but I have no clue the original value. When connected to a source, only the following image is displayed (Note: The picture is one 'solid' color, that black bar is not actually there; just the camera. The horizontal-sloping white lines are, though). Does anyone by chance know what this resistor was? I'm thinking I damaged the TDA3566 IC as well, the image is not being produced properly and it is the PAL/NTSC decoder. There's not much to these boards, so I'm hoping I can get away with replacing the IC and the resistor. Anyone else have any input on this? Thank you for your help!

[dick_barton]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

What pin number does the resistor connect to on the TDA IC. The schematic attached may give some idea of what value would be suitable.

[R_J]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

Whats the voltage on the resistor now, and maybe check the voltage on the same pin that is on the other plug (that was plug in here) just to see how much extra voltage it got.
maybe provide a clear picture of the underside of the board also

[laughatthemall]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

The resistor has a resistance of 268 ohm currently. I received a few of the IC's mentioned today, and popped one in. Well, I have display now, but it is acting weird. Please see the following video: The green hue, slight flicker, and the flickering bright green ARE all real defects, not just a symptom of the camera. Would these be likely to be adjustment issues somewhere on the board by chance, or some other defect? I've tried combinations of the side and rear knobs. I found focus, and (I believe; not sure on the following) brightness, gamma, and saturation as well. Thanks again!

Video:
https://youtu.be/dQLNAm7xgQo

P.S. I am attaching photos of where the resistor in question connects, as well as nice ones of the front and back just for anyone who might need this in the future.

[dick_barton]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

As in my earlier posting. What pin number does the resistor connect to on the TDA IC.

[laughatthemall]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

It appears to be 7, sorry. I tried to indicate that with the red dots in the first picture. I can't find a 'pin 1' marking on the IC though, so I am not sure if I started on the proper side of the IC. Only the divet, but that is in the center. Unless the Phillips logo is the 'pin 1' indicator, in which case, it's pin 22.

[dick_barton]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

Yes it is pin 7 after looking at your photo and is the sandcastle pulse input. Unfortunately not of much help in knowing what value resistor should be there. Sorry

[laughatthemall]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

Any hope for ideas regarding the green hue and the flicker, by chance?

[R_J]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

From what I can tell I have circled the Bias adjustments and the Square are the drive adjustment. See if each bias adjustment adjusts the level of its color, this will adjust the low level, black areas, usually done without video. but see if each control does adjust its color level.
the drive adjustments adjust each color to get white in the bright areas, but see if the bias adjustments work first,
The flickering could be something else but might be due to the burt resistor
It looks like that pin 7 line took the full +200 volt screen supply so who knows what happened inside the chip when that happened.
Have you replaced the burnt resistor with anything? I would try around 100 - 200 ohms
If the bias does'nt adjust for that color, check the small transitors for that color
Its hard to tell from the video but it does look like the picture is lacking red
Did you check the vcc for the ic? pin one should be +12 volts

[laughatthemall]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

*I have not tried adjusting the bias or drive. I will give that a shot.
*I have not tried replacing the burnt resistor. It still reads 268 ohm, so I'm almost wondering (hoping) it was a 270 ohm. It did light up good, so I of course would not 'trust' that if I could at all avoid it, and do intend to replace it. I'll do that next.
*The old IC definitely got destroyed. Swapping it with the new one I got yielded a functional screen.
*This is my first time working on a CRT so I am not too knowledgeable here; I would never touch them because of the dangers inherent, and because there was no real need -- CRT's have always been cheap enough since I've been alive. But, I figure I play with plasma SMPS' just fine, so why not? One-handing it as much as possible, of course. I 'thought' the green electron gun might be adjusted too high, since the overall hue is green. Note Mario's clothing -- I do see pretty vivid red, 'muddied' with green, at least in my opinion. That, and the green flashes that occur make me think maybe something is wrong with the green drive circuitry.

Thank you for your assistance here! I'll try these suggestions and report back.

[R_J]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

The aprox ratio to get white is 11% Blue, 30% Red & 59% Green. so green makes up most of the picture, I would turn down the green bias so the black areas are no longer green, then turn up red untill black has red tinge then back it off then do the same with blue. there are other ways to adjust properly but more complicated.
If the black looks black, then check the white areas and adjust the drive to make them white
This is just a theroy but.
If you look at the pdf of the TDA3566 page19 shows pin 7 with an internal 2k res. a transistor connected to +. So if you apply 200 volts (thats the screen voltage from the other plug) and if it went through those internal parts of the ic it could have shown up on the + 12 volt of the ic's vcc, so where does it get the +12 volts for the ic ? and was anything else that uses that + 12 volts damaged also?

[laughatthemall]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

I can't seem to get white, no matter where I go with the bias/drive combinations. I almost feel like something more was damaged. All colors seem to 'adjust' a bit with the drive (intensity) one, the other one is much much more subtle. So, at least that is likely functional. Any other suggestions? That 'flickering' really makes me feel like it is a symptom of the problem.

I tried replacing the resistor with a 270 ohm resistor, as the old one was at that value (not sure if it was before the huge voltage hit). Still nothing. I am not sure what to make of the flashing every once in a while. I almost feel that may have something to do with it.

The two plugs that were reversed now have the following DC voltages when on:

All plugs are listed left to right, when viewed on the connector side.

Top plug:
185v | 0v | 12v | 48v| GND(?)

Bottom plug:
1.48v | 0v | 1.09v | 5.4v | 0v

One thing I was wondering (fearing) is, could I have permanently damaged the tube? I'm almost willing to replace just about anything and everything on this board to fix it, and am likely going to try swapping the TDA2595 chip next.

Pin 1 at the TDA3566 appears to have 12.18v (power supply in), so that seems fine now at the least.

Thank you for your continued assistance!

[R_J]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

The tube should be fine, It would have damaged the transistors way before crt. The 185 took out the ic, but the 48 & 12 may have damaged parts also, trace where those lines go and see if anything else is bad, check around R129 & d101 The seem to connect that line to the base of those small transistors so one of them may be damaged

[powerismine]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

I am wondering if anyone knows if there is an adapter that can be used to convert the DB9 output coming from the SNES to VGA or Analog input so either a computer monitor or tv could be put in the place of this tube tv?

[RJARRRPCGP]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

Back to the early-1990s, folks. LOL. Cool. (1991) I was at the Vermont Achievement Center (VAC) in Rutland, Vermont, likely playing Super Mario Bros. 3 on an original-style NES (pre-Super Nintendo) at 77 Park St., LOL.
I never even touched a Super Nintendo at that time, IIRC, LMAO!

[truarcade]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

Does anyone have the technician's manual or schematic for this model (cd15mntc1)?

Thanks!

[J_White]

Re: SNES Kiosk Monitor ( Zenith CD15MNTC1 ) Problem

I have the same CRV as well; a Zenith CD15MNTC1. Recently had the SCART and DB9 cable repaired by a professional shop. However, I am still having issues with the picture. The color is very nice and vibrant, but the images appear scattered on the display. Which leads me to believe maybe a cap or decoder issue. Any advice would be appreciated, thank you.