NGCD Front Loader No Video or Sound

[Igbeserk]

Hey,

Wanted to see if i could get some guidance. Purchased a "Junk" NGCD Front loader version that has no video or sound. Indicated it powered on but nothing else. It came with no power adapter but i have a NGCD Top Loader so i used the adapter I had already. It powers on but i receive no audio or video. When I took it apart, I couldn't find anything that had been touched or messed with everything looked stock. I didn't find any blown caps, cut traces, burn marks, old cracked solder joints etc. I tried to touch up the points for the composite as well as a few other points on the daughterboard but that didn't do anything. I tried S-video and nothing. I snag a recap kit from console5 and replaced all the caps on the daughter and motherboard and still just a black screen. I went to the wiki to check out datasheets since there doesn't seem to be schematics and for the various chips I was able to find Datasheets on i was getting ground and vcc when i checked the points. the and many places i checked i was receiving the ~5v or ~9 volts. The only thing i found strange (but no information to confirm it is strange) an inductor and a transistor were giving me 8.01v on the daughter board (L3 Inductor - IC2 Transistor) which i found odd since everything else gave me ~5v/9v. Not sure what I should try to focus my attention on/check/confirm.

Any insight would be appreciated. Thank you

 

[Neo Alec]

Sounds similar to this one:

Neo Geo CD Front Loader - no video / audio

I picked up Yagamikun’s boxed top loader. Beaut of a system…but she’s blind and mute. No output on S Video or composite, no audio on the RCA lines. Tried two PVMs, Framemeister and an old 1080p LCF tv with composite in. Checked the AV breakout board. No obvious signs of issues. The power...

neo-geo.com

With that in mind, perhaps you're onto something with the power supply and caps. I would measure voltages starting from the power jack.

 

[Igbeserk]

Sounds similar to this one:

Neo Geo CD Front Loader - no video / audio

I picked up Yagamikun’s boxed top loader. Beaut of a system…but she’s blind and mute. No output on S Video or composite, no audio on the RCA lines. Tried two PVMs, Framemeister and an old 1080p LCF tv with composite in. Checked the AV breakout board. No obvious signs of issues. The power...

neo-geo.com

With that in mind, perhaps you're onto something with the power supply and caps. I would measure voltages starting from the power jack.

Ah,

Thanks for that. So it may be PSU related even though it works for the top loader going by the forum posts. I was using my NGCD PSU with a transformer as well so it wasn't just plugged into the outlet. I don't have another NGC power supply but i do have a few old dell/random power adapters that have the same connector for power that the NGCD's use. Guess I can wire up a 10v / 5v adapters and test it to see if that might do the trick. Appreciate the info Neo, I'll keep you posted!

 

[Neo Alec]

If you're in North America, try it without the transformer if you haven't already.

 

[Igbeserk]

Alright,
I tried without the transformer and same results. Although the screen seemed to pop more as if it was trying to do something. When I measured the voltage for the 10v aspect it was roughly 9.5v I believe. I found my two 10v adapters, one was for a retro all-in-one console and the other was from a sega. I measured their voltages one of them measured ~13v and the other measured ~16v. I have a few step-down converters so I lowered the 13v one to 9.95v and my 5v adapter gave me 5.19v. made my connector, tested and still no video or audio. I decided to bump up the 9.95v to 10.04v to at least clear 10v and still no video or audio. I checked the voltages on the board getting the 4.9V and the ~9.x as well as the 8.01v that was on that one inductor/transistor. No luck so far.

 

[Igbeserk]

If you're in North America, try it without the transformer if you haven't already.

a friend linked me to a post on how finicky the cd consoles can get if they're not getting 10v power on the components inside. So I removed the step-down and plugged the sega adapter (no load 13.65v) but the console would not come on. Ended up using the step-down and bumped the voltage up to 11, that allowed the console to turn on and the components were getting ~10.5v but still had no video or audio. I did find my 5 pin din connector and tried that and no video/sound from that either.

 

[Igbeserk]

I ended up trying a few things. Someone recommended I try switching out the bios chip, a bad one could be the cause of no audio/video. I tried both Unibios 3.3v and front-sp1.bin and no luck. Someone recommended I check out the RGB Encoder compare voltages to the datasheet and check the voltages on the 8 pin din port. Checking the encoder (CXA1645P), per the datasheet, the voltages I received were within range aside from Pin 10. Pin 10 is the SYNC IN pin, I should get roughly 2.2v, but when I measured with the multimeter I was receiving 4.5v. I tried to follow the trace of PIN 10 and it lead to a Resistor (2.2K ohm I believe) and a Ceramic Capacitor with 47 listed on it with a line underneath (maybe 47nf?). I kept the system on and probed pin 10 for continuity with other components on the board. First chip I tried was the yamaha (2610) chip, a lot of pins were giving me continuity which I thought was strange. I checked Pin 10 with GND and had continuity, I checked with the positive side of some capacitors and got continuity, checking with other pins on the CXA and I received more contunuity. Seems at least when the console is on, either by design, or a short is being created? not sure. The 47 capacitor when the system is on gives me continuity on both sides when off only on one side. I started to check out the other pins on the CXA chip, I noticed if i touch Pin 2/3 or 4 (R/G/B) to Pin 12 (vcc) whichever color I checked for continuity gave me that color on screen. This is the first time i've gotten an output on the screen. I have a few replacement CXA1645p's, I debated on swapping out the CXA to see if that might resolve the issue before I proceeded, I disconnected the daughterboard from the mainboard and checked the voltages/continuity again. This time Pin 10 gave me 2.25v which is .05v more than what the data sheet indicated also, I did not have continuity with ground/positive or the other side of the 47nf capacitor. It seems like something on the mainboard is causing the daughterboard or pin10 off the cxa chip to act up? Gonna see if I can figure out what pin 10 should be leading to definitely tougher without schematics but this is what i've discovered so far.

 

[Igbeserk]

there's a short on the mainboard somewhere. can't pin it down. With the daughterboard disconnected so no load the cxa chip gives me correct volts but with the mainboard connected that pin 10 gives me double the voltage it should have. i tried to follow pin 10 trace led me to a wire that connects to the mainboard. if i disconnect the wire then the voltages are fine. anyway, I tried a thermal camera found a cap that lit up right away, touched it and it burned my finger. I removed it and i still have a short with vcc/ground. not finding any other components that heat up like the cap. not sure what to try next. I've tried checking caps and other components to see if i get continuity where i shouldn't but so far no real luck.

 

[maki]

The NeoGeo CD needs 5.5V and 10V to operate, 5.0V sharp won't do.

edit: you had a hot cap, missed that part

edit 2:
here is the schematics of that power board