Replacing motirzed projector screen controller with arduino

Hi,

I recently got myself a motorized projector screen which is controlled by some chinese board called Tj7500.

Since this board got damaged while shipping and i'd like to control the screen with my phone i'm thinking about replacing the board with an arduino.

But i'm not quite sure how to drive the motor.. can i just buy a motor driver module for arduino and use that? If so, could you point me to which one i should use?

It runs on 230V wall power hope you can figure out a little more from the picture below.

BlackTSQ:
Since this board got damaged while shipping and I’d like to control the screen with my phone I’m thinking about replacing the board with an Arduino.

Where is the damage?

The first rule in situations like this is to have the original working properly, then you may be able to add some functionality.

The picture is from the internet.. my board looks like this although it's still functional.

i already replaced the power in cable to avoid any shorts the old one might cause (not on the picture).

FYI, on the other side of the board are 3 buttons, one for down, one for up and one to stop the projector screen. If down and stop are pressed at the same time the position gets saved. So the next time the screen goes down it will stop at that position.

So I could probably just activate those buttons with an arduino, but i would prefer replacing the whole thing.

I did some more digging and found out that there's probably a 60ktyz motor used.

Should work somehow with some relais and triac s ? :confused:

I see two relays (the big black things), some capacitors, an inductor and something that looks awfully like a crystal. There must be more to this board - probably some kind of microcontroller, hidden on the back. It's some kind of "digital controller" which supports that idea.

Sounds like you can control this with an Arduino. My best guess is that the two relays are for up/down control, probably in H-bridge configuration. The lack of an obvious power supply suggests these motors are actually running on 220V AC, so probably not an H-bridge after all but a different trick (I'm not at all familiar with AC motors).

wvmarle:
The lack of an obvious power supply suggests these motors are actually running on 220V AC, so probably not an H-bridge after all but a different trick (I'm not at all familiar with AC motors).

Capacitor run.

Ah, right. That makes two relays make complete sense, and would make it quite easy to operate by an Arduino. Relay module with two relays; two outputs from the Arduino; and some form of input to give the commands for up or down.

Just wondering: what would happen if both relays are closed? So both 1 and 2 in your drawing connected at the same time. The motor I may assume won't run but anything bad happening?

wvmarle:
Just wondering: what would happen if both relays are closed? So both 1 and 2 in your drawing connected at the same time. The motor I may assume won't run but anything bad happening?

Very bad! Stalled motors overheat.

However most of these relays are SPDT, so you chain the NC to the next common.


I still maintain that the clearly most sensible thing is for the OP to retain the original controller, and use optocouplers to mimic the buttons with the ESP8266. :roll_eyes:

Thanks for the helpfull replies! :slight_smile:

If i use optocopplers do they have to be rated vor 220V? Maybe you can suggest one that i could use, that would be great :slight_smile:

I'm gonna unscrew the circuit board today and send you a picture of the other side of the board if that helps.

BlackTSQ:
If i use optocouplers do they have to be rated for 220V? Maybe you can suggest one that i could use, that would be great :slight_smile:

Optocouplers have an isolation rating much greater than 220 V - generally several thousand. That is in fact why we advise their use.

On the other hand, the switches you would be connecting them to will necessarily operate at something like logic levels within the device, as do the relays (which should have voltage markings) so the ratings of the phototransistors in the optocouplers will be quite adequate.

BlackTSQ:
I'm gonna unscrew the circuit board today and send you a picture of the other side of the board if that helps.

Excellent idea! :grinning:

Make sure it is in bright light - such as outside daylight but not sun, and full detail with sharp focus.

Paul__B:
Excellent idea! :grinning:

Make sure it is in bright light - such as outside daylight but not sun, and full detail with sharp focus.

Thanks!

Will do, the other pictures quality is only that bad because i originally captured it just for damage report purposes to the seller ^^

A little late, but here the promised back side of the circuit board:

Need the top in the same detail to match.

Can you read off the markings on the 8 pin chips? Could even be 555s.

The relays are 5 V which I find a trifle surprising as this means they draw more current than if they were 12 or 24 V and this has to be supplied by the series dropping resistor.

The relays are SPST, so cannot be "chained" as I suggested before, slight risk of both being actuated simultaneously.

What was the transit damage that concerned you?

No isolation from the mains, so you will need opto-couplers and careful wiring. I am very surprised that this operates at 220 V, it looks more like a 24 V design fed with a transfomer.

Paul__B:
Can you read off the markings on the 8 pin chips? Could even be 555s.

The upper one says WS480S the other one is blank. I did some digging on the WS480S and only found some chinese websites where it is suggested that it's an SYN480R which would be a cheap clone of an 433M Wireless reciever module.

That would make sense, since the whole thing is controllable via remote aswell ^^

Well... i fried my board :frowning:

I wanted to short one of the buttons with a screwdriver to see if i could just solder the optocopler to it in paralell and accidently touched one of the power input wires aswell ...

I think most of the components of the board are still in tact, but the board itself is dead.

Now i'm asking myself if i should try rebuilding the circuit with the original components (after testing them of course), or if i should try building my own circuit :confused:

The hard part of a rebuild is the receiver: the frequency and protocol of the signal transmitted from your remote control.

As you created a short - I may assume you mean 220V to the components - I wouldn't trust anything that's still on the board to be safe and functional.

I'm pretty sure the same motor as in this video is used in my procetor screen:

So shouldn't i be able to replace the double-pole-double-throw-switch with a relayshield?

wvmarle:
The hard part of a rebuild is the receiver: the frequency and protocol of the signal transmitted from your remote control.

As you created a short - I may assume you mean 220V to the components - I wouldn't trust anything that's still on the board to be safe and functional.

I don't really need the original remote since i plan on making it controlable via smartphone

BlackTSQ:
So shouldn't i be able to replace the double-pole-double-throw-switch with a relayshield?

Probably - you best study the PCB you have in more detail, and find out how the power lines are connected. You have the mains input; presumably going to the two black boxes (relays?), and from there to the three output wires. That appears to be the main part of the board that you have to copy/rebuild.

With the type numbers printed on the black boxes you will be able to find out the pinout and how they work exactly, and that way figure out the way it's switched. Paul__B gave you a circuit in #5, and mentioned in #13 that the relays are SPST. The two relays may act as the toggle switch as shown in the schematic.

I followed the traces on the pictures, the yellow ones are the ones i’m quite sure of, the orange ones i can’t really see because they are blocked by the components. But i don’t see any other traces where they might go.

I’m going to take a closer look when i’m at home and have the pcb at hand.


online fotos hochladen

Use a multimeter and you can be sure of what is connected to what :slight_smile: Though this is looking very much like the switch as in the schematic of #5.

That motor shouldn't draw much power, meaning just about any dual relay board will do. An ESP01 can easily control the thing. Just add a power supply (probably 5V for the relays; 3.3V for the ESP).