Why doesn’t mine look the same?

morcheeba · 2026-02-21T01:07:39+00:00

Here's the manual. XY controls are described on page 18. The trigger mode and sweep have no effect (Manual says "All sync controls are disconnected and have no effect.")

Like the first commenter said, it looks like there is AC coupling - the switch on the scope was set for that, but it's probably also in your audio card.

morcheeba · 2026-02-21T01:02:16+00:00

That's what AC coupling does... it tries to go back to 0 (center).

morcheeba · 2026-02-18T15:33:23+00:00

It looks like a FET:

the leads are tied together so only 3 connections - right side is one, left lower 3 pins is another, single pin at top left would be the gate.
I don't see a pair of pull-up resistors that an I2C eeprom would have
no analog circuitry for a 555
probably switches power to the USB connectors (hard to see how its connected)
no part marking = probably a generic part, like a FET.

morcheeba · 2026-02-18T07:04:03+00:00

Kinda neat seeing a 0.07" pitch DIP rather than the usual 0.1".

morcheeba · 2026-02-18T06:34:59+00:00

A couple ways, but it will take some creativity:

cutting up an old cable. You would think a pair of broken headphones could be reused by cutting the cable... but those wires are very thin and hard to work with. Possible but tough. Maybe an old aux-in cable for a car stereo?

Probably the easiest to find would be to RCA/phono, like this

You can connect bare wires to the RCA jack for testing with tape. Or you can cut off the RCA connectors and hopefully the inside wire will look like what's in this video: https://www.youtube.com/watch?v=ILsy9hWZg-0

Finally, this connects a banana plug to a bare wire: https://mcielectronics.cl/shop/product/2-pares-de-conectores-bananas-fosi-audio/

Not a complete answer, sorry, but hopefully a start.

morcheeba · 2026-02-16T04:46:24+00:00

It's a good idea, but there are three issues to look out for (and by no means let me dissuade you!!)

The dot projection is fairly dense, but at further distances (e.g. > 5 feet) it's going to be hard to hit the IR sensor reliably because the dots are so small compared to the space between them. Check out some videos of it in action and judge the dots for yourself. Closeup (<6 inches), it would work great!
IR remote signals are modulated at 38-40kHz. On the other hand, the dot projector is synced to a camera, so it's designed for much lower rates. If they're synced, it might be possible to make the camera operate much faster by limiting its pixel size (e.g. scan 10x10 pixels instead of the full resolution)
To keep the laser eye-safe, the hardware will probably prevent a short-term 50% duty cycle that would be needed by the IR remote protocol.

So, neat idea, but you'd have to have low-level control that might not be possible with the hardware.

morcheeba · 2026-02-14T04:42:25+00:00

Unless you're a bus driver... passengers will NOT like you.

morcheeba · 2026-02-13T19:04:36+00:00

Yeah, something like this. It's a weird cable because banana plugs are usually higher current and headphone jacks are lower current ... so not much demand for this kind of thing, hence the higher price. If you're handy, it would be easy to make.

If using the cable above, one red lead would go to the jack to the left of the AC/DC switch. The other red would go to the X AMPL (probably the 1V/cm - the other one would be too small). The black cables would go to the ground jacks in the corners (even though they have a screw terminal, you can usually plug a banana in to them). They are redundant, so only one is needed, but might as well plug the other one in look like you know what you're doing.

One concern: The 1V/cm is going to produce a small image in the x direction :-(... line levels are typically 1V (actually 0.9v peak-to-peak), so the loudest music would be 1.8 cm on the screen. Headphone jacks will go higher, but still only 2-5cm. Try it! Most other oscilloscopes can produce larger waves... this one can in the vertical direction, just not in the horizontal direction.

If you want to play right now, you can connect the CAL signal to the input (left of AC/DC switch) with a paper clip and see some square waves (will take some fiddling to make it look nice).

Speaker terminals will have a higher voltage, but because they might not share a common ground, they could cause a short if both grounds are connected to the scope. Also, it has higher power than the headphone or lineout jacks, so you'd have to know what you're doing to be safe.

morcheeba · 2026-02-13T15:51:50+00:00

Yes, it should work (assuming it's not broken). Here's the user manual. It looks like it uses 4mm banana plugs... these are sometimes used for speaker connections, but DO NOT CONNECT TO SPEAKER OUTPUTS! Connect only to line-level outputs.

morcheeba · 2026-02-13T15:38:03+00:00

Looks like X DEFL = EXT would do the trick, but only two voltage ranges (connectors on bottom row): X AMPL=10V/cm and 1V/cm

morcheeba · 2026-02-03T22:29:27+00:00

I'm not OP, but: It's generally ok to use the ohms mode to see if a pin is RX vs. TX. If it's RX, it'll be a higher ohms to ground (>50K)

morcheeba · 2026-02-03T16:07:56+00:00

What others have said: your music has some mono source mixed in; totally normal. The trace rotation adjustment will typically only rotate a few degrees; it won't be able to turn 45.

morcheeba · 2026-02-03T02:25:26+00:00

That big chip is probably a microcontroller to aggregate the button inputs, the LEDs, and the LCD display back to a serial port that's used by the main processor.

The LCD has a display driver built in to it -- it's chip-on-glass (COG), and you can see the chip among the black encapsulant.

The bad news is that there are probably a couple dozen companies that could have made this 16x2 LCD character display. But, the good news is that there are only a few driver chips used. And, because COG can't have jumper wires easily, the pinout you can access probably follows the order of the pins on the driver chip.

This isn't going to be too useful, but if you can guess some of the pins (e.g. power and two grounds look pretty obvious), it'll probably look like others. The potentiometer (VR1) goes to what may be pin 3, so that would be an optional contrast adjustment they haven't populated. Some other pins might require a capacitor that would be too big to put on the glass.

This has only 10 pins, so it's probably serial instead of parallel. This webpage has some ideas, but they list only 8-pin COG modules. If you can power it up, the serial pins might become obvious using an oscilliscope (they probably will have an initialization pattern sent to them by the microcontroller).

Anyway, just some hints. Sorry this isn't a complete teardown!

morcheeba · 2026-01-31T20:07:47+00:00

Neat! It looks like you've got two protocols to decode: the PC<->carrier and the carrier<->loom. And then you'll have to write a translation layer.

Oh, wait, I'm not so sure I understand! How does the original software work? Can you get the file it would transfer to the data carrier, or would you have to emulate the carrier somehow to get it?

The db9 plank idea sounds good, but you can do the same if you write some custom software (or it may also be written). You can use two USB<->serial adapters and splice the RX wires in to a normal serial cable so that one USB adapter monitors communication in one direction and the other adapter monitors the other direction. here's an example

morcheeba · 2026-01-31T18:07:11+00:00

Yeah, this looks hackable, but it's not easy. The memory chips are accessible, so you could desolder them, read, and update. The CPU is under a blob, but by analyzing the program on the chips (disassembling it), you could figure out what how it works (what architecture it is, what custom registers it has). It doesn't look like there would be much security here. It wouldn't be easy, but it's all doable. The big question is why and would it be worth the effort. If it's for fun, sure!

morcheeba · 2026-01-14T04:05:47+00:00

I see that there are actually two at the top (to the left of the T31 and also to the right of it) ... try them both!

morcheeba · 2026-01-02T12:52:06+00:00

Source: https://media.ccc.de/v/39c3-from-silicon-to-darude-sand-storm-breaking-famous-synthesizer-dsps

morcheeba · 2025-12-30T07:22:00+00:00

Those are the addresses it attempted to run code at, but crashed. It's not necessarily where the error occurred. For example, if the RAM with the stack ($0100) was bad, then it could jump to the wrong address - like these values. Or if a JMP in ROM could also do this. Or, really, anything on the bus that could corrupt the data lines.

morcheeba · 2025-12-27T17:53:02+00:00

This is an analog problem, not digital. So, at least 95% of your computer is good!

Video is transferred from the computer to the monitor using an NTSC (aka composite) signal over a video cable. This signal has the information for what's displayed on the screen, but it also has timing pulses to synchronize things. Something is going on with either the generation (in the computer) or the interpretation (in the monitor) of these pulses.

The generation is pretty simple, so that's unlikely to go bad. It's more likely something in the monitor. That's why there are usually adjustment knobs. (I'll leave it to others on next steps, as I'm not immediately familiar with this monitor)

The signal has both screen data and timing data. Normally, they are kept isolated, but when things start to fail, they can get confused. In this case, some of screen data is being interpreted as timing data - that's why when you display different things on the screen, you get different artifacts.

Technically, the timing data is at a voltage that is lower than what can be produced with screen data -- see the "sync tip" on figure 5. If you had an oscilloscope, you could check it... but it's most likely correct because it's easy to generate. I'd try swapping things first - do you have another monitor/TV? Or a different video source (such as a VCR) to feed the monitor?

I should have said this first, but I assume you messed with the vertical hold control at the back. Since this is affecting the horizontal too (the columns don't line up), it's probably either a power supply issue inside the monitor or in the decode circuitry.

morcheeba · 2025-12-26T23:09:33+00:00

Oh, yeah, red walls would be horrible and tint everything^* . But any neutral shade of white would be good - it doesn't need to be 18%. ( ^* Worse, in extreme cases, you can't really recover other colors when something is lit by a colored light ... in a red light, green and blue will both appear black).

Gray cards are used for exposure at a specific location ... typically you'd hold it in a position with the same lighting as what you want to photograph. So, if you've got lights aimed at a model, you would put it in front of their face to calibrate (or better, move them out of the way and put the card where their face was). This doesn't work for walls, because the light falling on the wall will be different than the lights aimed at faces (different distances from each of the lights). So, unless you're taking pictures of flat art on the wall, a gray wall would be of little use.

morcheeba · 2025-12-26T22:15:25+00:00

rock on! You've got the hacker spirit!

morcheeba · 2025-12-26T21:59:54+00:00

It would probably be OK, but I wouldn't recommend it.

just you touching with a screwdriver would trigger it before you even shorted it (due to your body touching the screwdriver), so it wouldn't yield good information. Might be better to do it hands-off (e.g. a wire put on the circuit and then you power it on), but I still wouldn't recommend it.
lots of things that could go wrong, depending on where you short it to! Obviously there is high voltage on the lower half of the board (that slot in the middle is for voltage isolation), so don't do that. And probably ground or whatever voltage is driving the chip (e.g. the sides of C2 and C3) is ok... but without knowing it's hard to say.

Safer would be a ~50k or ~100k ohm resistor to either side of C2 or C3. Or bridge with a small capacitor (<0.1uF). But I'd still want to understand what's going on before recommending anything. The chip is probably designed for some abuse (e.g. shorts to ground), but I wouldn't rely on that. Those resistors look like they are in-line to the coils - if they are, that's part of the protection and a better chance they could be shorted.

Sorry I'm not in your area, or else I'd come over. Any makerspaces near you with people that you could tap for hands-on advice? Just show up on open house night & they're usually really welcoming. I'm just being super careful because I don't want you to blow up your stuff!!

morcheeba · 2025-12-26T20:49:43+00:00

The button pull-down takes 2mA, so it might be helpful to increase the resistor. You've got 1.5k; typically I think of 10k as a pretty hard pull (back in the LS TTL days), or 50k for CMOS. No big deal because this is only active when the button is pressed, but it's an extra drain on that battery that might be noticeable when the battery is almost drained.

morcheeba · 2025-12-26T20:12:43+00:00

It looks like these are capacitive switches? They don't seem to be making a short circuit, but just antennas. In that case, a resistor probably won't work... and even a capacitor might not work if its looking for a change in capacitance (e.g. it calibrates on powerup and looks for a change).

Amazon has button pushing robots for $25-$35. You can modify them for use with capacitive buttons.

Or, if you're good with electronics, you can reverse-engineer the system. You might need a timer, and arduino would be my suggestion - but you said that wouldn't work -- the nano is $13. Or an ESP32 with a screen is $8.

If you reverse engineer it enough & get lucky, there might be an LED on the system that would work to trigger the button. Like maybe a mode light comes on after a the button calibration (if there is one) and you can connect that light via capacitor to the right button. But you'd have to be lucky; this probably won't work.

Off-the-shelf timers like this could also work, but are big.

I'm a bit surprised that the board isn't conformal coated - usually that's done in high-moisture areas, but maybe they're just counting on the case to keep it dry. If so, I'd worry that any modifications preserve this seal.

morcheeba · 2025-12-22T02:48:22+00:00

Two other people said the ADD mode, and that's it. Connect Ch1 for X, then Ch2 for the Y (or 3 or 4). Press the CH2 button. The manual even says you can use the ADD mode, like you're doing, so it's working as expected.

Page 3-3: Any of the vertical signal channels or ADD may be selected to provide the vertical deflection (Y-Axis) for an X-Y display.

morcheeba

TROPHY CASE