Strange lines on chihiro screen

[bobbydilley]

Just bought a new Chihiro and have some issues with the monitor output as shown on the picture. The Chihiro is from one seller and the AVIP is from another, so I'm trying to work out whats at fault here.


The lines sort of jump about, and possibly move when I wiggle the cable but its hard to tell.

Anyone experienced anything like this before? I'm thinking of trying to use an old XBOX AV cable to see if I can get any output without those gagged lines on a TV. Has anyone tried this with either the component/composite/s-video xbox cable and can tell me which one works?

Any help is appreciated!

Bobby

 

[obcd]

The chihiro bios outputs a vga signal. I have successfully used a scart RGB cable. The strange thing with a chihiro is that it pulls all 3 avip inputs to gnd. (This behavour is selectable with some of the dip switches on the filter board) That's the same you get when you plug in a scart cable. On the base board, you will find an LM1881 that extract the composite sync from the green color. So, on the vga connector, you only get composite sync on the hsync pin and nothing on the vsync pin. Not all monitors like this. Some I have simply indicate no video signal (probably due to the vertical sync missing) others have a picture that occasionally flashes axway for a second.
I build myself a sync separator with an lm1881 and it also shows the image with that. Some monitors are able to extract the sync on green themself and don't need it. I had to use a separate 5V supply for my lm1881 as the xbox 5V wasn't available on the scart plug. I also had a less noisier picture when I mounted an additional ground wire between the monitor and the chihiro. The scart cable is a cheap chinese one, and the color signal wires are unshielded. There also was only one small ground wire for all the color signals and the audio signals.

You could try a little contact cleaner on the bottom connector of the avip cable. I have had some bad contacts occasionally there.

Another thing I would try is another monitor (if you have one available) The chihiro outputs a 640 x 480 x 60Hz vga signal. Sometimes it's interesting to turn on the monitor osd to see what resolution it displays.

Something also worth checking is the ripple on your 5V supply rail. If the capacitors surrounding the cpu start to dry out, the ripple will increase and that can cause interference with the video signal.

 

[bobbydilley]

Different power supplyy completely fixed the issue. Funnily enough the green light on the chihiro was flashing with the other power supply, so I’m assuming that means something wrong with the power?

The capacitors where all changed by videotronicsuk so they shouldn’t be old

 

[obcd]

On the filter board you have the 3 colored led's on the side. Those simply indicate 12V, 5V and 3V3 are present.
The 2 leds in the middle represent the eject button leds you had on an xbox.
green and red being simultanously on was orange on that button. (it used bicolor leds)
Some of the led codes are identical to the xbox ones.
My "outrun 1 game image" also produces a flashing green led. It's basically software controllable.

What power supply did you initially use? I have seen sun supplies with bad capacitors.

 

[bobbydilley]

The 3 LEDs on the front for the power rails all light up, although the 3v3 seems slightly dim but I believe thats just the LED, as its the same brightness whatever PSU I use.

I'm using ATX PSUs with a cable to convert the ATX connection to JST.

My 260watt server PSU managed to boot the Chihiro fine, with no screen issues and a solid green status 1 light (the green one next to the red one).
My 550watt desktop PSU (which is probably of much worse quality) manages to boot the Chihiro fine, but has the screen issues you can see above, and a blinking green status 1 light.

Whats even more strange though is I have 3 different PSUs, the server one (S), the desktop one (D), and a pico-psu (P) and the compaibility is below:

                        S D P

NAOMI                   1 1 1

SYSTEM SP               0 1 0

LINDBERGH               0 1 0

CHIHIRO                 1 0 0

So there seems to be no reason to which PSUs they accept, and they all have different preferences.

 

[obcd]

It could be an issue of minimum load conditions. Atx psu's expect expect some minimum load on their 5V and 3V3 rails. Some work fine without load but others simply won't even start. I have no idea how the chihiro loads it's supply rails. Some electronics on the base board indicate there might be a step down converter on that board.

 

[obcd]

I just reversed the base board a little. There is a step up switching converter that makes 5V from the 3V3.
That 5V is used to power the dimm board.
The supply 5V is used to power the main board. The base board microcontrollers are powered trough the usb gameport connectors.
If you unplug the base board usb connectors, the video signal dissapears as well as the base board has some video signal amplifiers and the sync separator that is also powered with the gameport 5V.
The base board can turn off the power supply rails. At that moment, they likely aren't loaded much anymore.
Maybe it takes several milli seconds before the unit starts up.