Anyone ever work on a Goldenstar Disco RGB projector?

[buffo]

Hey guys;

I'm working on a projector for a fellow PL member. I've installed a new set of scanners (faster ones) in an old Disco RGB projector from Goldenstar. I've also installed the newer projector electronics (SD card reader, LCD display, and main board that handles DMX inputs, interlocks, and switching between the card reader and the ILDA-in port) inside the projector to allow it to scan the stored artwork on the SD card at a full 30K. (The old board only went to 10K.)

So here's my problem: With everything hooked up, I get no X or Y output to the scanners, no matter if I'm running off the SD card or the ILDA port. The color signals are being passed on correctly, but I get no X or Y signals.

I'm concerned that I may be missing a key wiring harness. On the old projector there was a "min-max" potentiometer on the back. There were only two wires coming off it, and they went to a set of unlabeled pins on the old main board, right next to the microphone input. I'm assuming this pot was for size adjustment. But on the new board, there isn't any clear place to connect this pot.

Even more troublesome, there is a pin header with an "x size-line" and "y size-line" series of pins, but I have nothing to connect here. Each set is 3 pins, one set is labeled X+, XO, X-, and the other is Y+, YO, Y-. Note that these are completely separate from the X and Y signal outputs on the bottom edge of the board that I'm using for the scanners.

Finally, on the same pin header with the x and y size-line pins, there are two pins near the top (just below the microphone input pins) that are not labeled on my drawing, but on the board are labeled RP1 and RP2. I have no clue what they are for.

So here's the rub: I've contacted Goldenstar about this, but everyone there is on Holiday, and Mimi herself isn't sure what is supposed to be connected to these pins, if anything. I wanted to get this projector finished this weekend, but without more information I'm stuck. Does anyone have any experience with these Goldenstar boards that are used in their Disco RGB projectors?

Here is a drawing of the board I'm talking about. Note the long pin header on the right - that's where the X and Y size line pins are located.



Things I have already tried:

1) connecting the pot on the back of the projector to the RP1 and RP2 pins. No effect
2) connecting a 10K pot across the X- and X+ pins on the size line header with the pot wiper connected to X0. No effect
3) installing a shorting block between X- and XO, and alternately between X+ and XO. No effect

Anyone got any more ideas?

Adam

[DZ]

My next step would be to fire up the o'scope. See what signal, if any, is on the X+, XO and X-.

[buffo]

My next step would be to fire up the o'scope. See what signal, if any, is on the X+, XO and X-.

Good call. Guess it's time to start digging. Thanks for the suggestion - will let you know what I find.

Adam

[buffo]

Eh - turns out those pins are for reversing X and Y. Connect the X+ to Xo for normal, or X- to Xo for inverted, and so on.

Installing shorting blocks was the right thing to do. However, there was another problem that I didn't catch during all my previous troubleshooting: the X and Y outputs are single-ended! I had foolishly assumed that the "RPX" and "RPY" pins were the negative halves of the differential X and Y outputs. But nope, that's not it! All you have is X+ and ground, and Y+ and ground. Those other pins aren't even connected!

So with a quick re-wiring of the cables to the scanner amps, this projector is scanning again!

Whew...

Adam

[jors]

Hey Adam,
R you sure X and Y outputs are single ended? sorry, I think not... this is how mine is wired:

Also, if single-ended... why card needs differential power supply? (+15V, Gnd, -15V). It has nosense...

[VibrationsOfDoom]

Just out of curiosity, wonder if that weird microphone knob on the back of the projector can be "wired in" to the x and y SIZE of the images, since the new LCD screen and hardware doesn't have a menu setting to increase or decrease the size of the images...

Still, SD card may be a thing of the past... QS controls this thing VERY well...

[jors]

Yes. And You're right. No flip-size option on menu setting, but you can Invert (flip) & size turning X-Y pots. They affect on ALL projection modes, auto 'sync' with mic, sequential effects (both internal card effects) SD playing and ILDA as well.
It seems all internal FX stuff also SD card is TTL, so 7 colors...but not sure..I always go thru ILDA with QS FB3 & analog modulation.

[buffo]

Hey Adam,
R you sure X and Y outputs are single ended? sorry, I think not... this is how mine is wired:

Jors:

I assumed this as well. The first time I connected the board, I wired it up exactly as you have it pictured in your drawing. But it didn't work! Then I got the oscilloscope out and started tracing signals.

There is NOTHING on the RPX and RPY pins on Steve's board. The only way I could get any waveform was on the X and Y pins. When connected between those pins and ground, I got a normal waveform. But hook it up any other way, and you get nothing.

Also, if single-ended... why card needs differental voltage power supply? (+15V, Gnd, -15V). It has nosense...

I completely agree. But the oscilloscope doesn't lie.

It's possible that the board has been re-designed. Or perhaps this one is defective. But there certainly isn't any signal on the RPX and RPY pins.

Furthermore, I tried connecting a 10K pot between the X+, X-, and Xo pins just as you showed in your drawing. This had no effect; I couldn't get any signal unless the pot was full left or full right. (See my initial post above where I explained all the tests I performed before I came here asking for assistance.)

Bottom line, it's working now - but not in the manner I expected, and definitely not in the way you would assume based on the board layout. I can't be sure if it's a problem with this board or a difference between this one and yours, but it works this way and does NOT work the way you describe in your picture. (Although I admit that it makes much more sense when wired the way you show it. That's why I actually tried that set up first, before I posted here.)

wonder if that weird microphone knob on the back of the projector can be "wired in" to the x and y SIZE of the images

You would need two separate pots or a dual-gang pot to make that work. Using a single pot would short the X and Y signals together and you'd end up with a diagonal line and nothing else. That being said, now that you have the FB3 hooked up you can change the size in software.

Adam

[jors]

Thanks Adam,
I've been searching for info below pcb about revision or manufacturing year but no info at all
This pcb is detached from a projector (1W) I purchased from Mimi 5 months ago for testing purposes...poor projector hahaha
It comes with 30k goldenstar scanners. All I can say for sure, is Pots works well on fliping and resizing, but I don't really know if my board is single or differential ended.
All three pins are wired to scanners drivers for both X and Y, but perhaps RPX and RPY are not connected on the pcb as you pointed, grrrr don't know.
I have multimeter but not oscilloscope, could I test output signal setting multimeter to Ac voltage?

Also, if you are going from single ended to differential galvo inputs driver... do you loose 50% on scanning size?
Thanks!

[buffo]

I've been searching for info below pcb about revision or manufacturing year but no info at all

Hi Jors;

Yeah, I found the same problem. I was writing to Goldenstar to ask questions about the board, but I had no way of identifying it because I couldn't find any serial number or other marking to specify exactly which version I had. In the end I sent a picture and that worked.

This pcb is detached from a projector (1W) I purchased from Mimi 5 months ago for testing purposes...poor projector hahaha
It comes with 30k goldenstar scanners.

Steve's original projector had a much earlier version of this board that looked very different. I think Steve has owned his projector for a couple years now. Anyway, the original board would only scan up to 20K. Well, you could set it to go faster, but according to Mimi the older version of the board wouldn't actually run any faster than 20K. They did this because the original scanners were only rated for 20K. (And to be honest, they should have been rated slower! I think they were probably 15K scanners that were being over-driven.)

All three pins are wired to scanners drivers for both X and Y, but perhaps RPX and RPY are not connected on the pcb as you pointed, grrrr don't know.

It may be that you have yet another version of the board. This new one we have been working with was sent to us as a replacement for the original board. But I don't know if it is the latest version or not. Then too, it may be that this particular board has a fault on it. All I know is that there aren't any signals on the RPX and RPY pins.

I have multimeter but not oscilloscope, could I test output signal setting multimeter to Ac voltage?

Not really, no. You might be able to get some measurement, but it wouldn't be accurate. Still, if you have it set to AC voltage and you are displaying a circle with a relatively slow scan speed, you might be able to detect the presence or absence of a voltage. That would at least tell you if there is a signal present. But this assumes that the waveform is close to a 60Hz sine wave (which is what your multimeter would be detecting if set to AC voltage). Getting the X (or Y) signal to approximate a 60Hz sine wave is going to be tricky.

if you are going from single ended to differential galvo inputs driver... do you loose 50% on scanning size?

Yup. Sure do. Also, you have the potential for increased noise. You can adjust the input size pot on the scanner amps to compensate for the smaller size, but there's nothing you can do about the noise.

Adam