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PIN2DMD - won't start on power-up.


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I've got a 192x64 Evo installed in a Frankenstein - when I previously posted that it wouldn't self reset on power up, Lucky suggested a power supply issue as I was trying to use the machines 18V power supply (though looking at it, this comes from quite a substantial supply in the Data East machine (its an 8A fuse and a massive electrolytic).

As Lucky suggested, I fitted a separate supply (a 4A, 12V switch-mode) that is controlled from the machines main power switch. Unfortunately, the display still doesn't come on when the machine is powered up - pressing the reset button brings it all to life and once on, the display is excellent - I'm really pleased with it - excellent work Lucky.

Any suggestions on what else to try - Is there a circuit diagram for the Evo - I am happy to fit an external reset control IC as I've used in many of my own processor designs.

As ever, all help much appreciated

Peter

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This is a hardware fault that I myself and a few others users have had. My last batch of units had 3 with this issue unfortunately so it’s time to try and work this out as more and more people are getting it.

So far it has been reported only on the Evo x32 units but this is the first that I’ve seen it happen on the x64

Could you tell us if the evo was manufactured by pcbway? 

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How do I tell if it was made by PCBway?   I've had a look at the circuit diagram - its the traditional way of controlling the reset line and as per the datasheet. 

What was the solution on the cards you had?   Reset controllers are cheap and easy to use but, would be nice to try and get it to work without - bigger capacitor to hold the reset line low until the supply comes up? 

Happy to help try and get to the bottom of this.

 

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I think it is not a general design failure because more than 99% don´t have that problem. 

I guess it is a capacitor issue and I already suggested to change all capacitors around the cpu to see if that changes anything.

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Thanks as ever Lucky - no suggestion its a design issue - I'll stick  scope on the reset line and check the rise of the reset line - I have SMD soldering at work so happy to whip the 0.1's off as needed. 

I'll update when I've worked out what the issue is. 

Thanks for everyones help

 

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13 hours ago, lucky1 said:

I think it is not a general design failure because more than 99% don´t have that problem. 

I guess it is a capacitor issue and I already suggested to change all capacitors around the cpu to see if that changes anything.

I don't think it is a design failure either, only a small % have this problem but it is becoming more and more prevalent.

I'm actually working with PCBway again to try and sort it out on their end to see if it's a problem with the manufacturing process on their end, a bad component or possibly a bad batch of components from a certain supplier. If it's a certain component it could be a faulty batch from their supplier. For the last problem like this with the switches, we got them to switch the supplier/brand and I haven't had a switch failure since. I am hoping it is the same kind of thing.

As it is Lunar new year things are a bit slow but I will be speaking with them again next week. In the meantime @Frankensteinowner if you get time to swap those capacitors off and see if it helps that would be awesome. I don't have a SMD soldering equipment but if it is only 1 component that we are sure of then I can test that on my boards too. I would have to order the parts to replace though.

13 hours ago, Frankensteinowner said:

How do I tell if it was made by PCBway?   I've had a look at the circuit diagram - its the traditional way of controlling the reset line and as per the datasheet. 

What was the solution on the cards you had?   Reset controllers are cheap and easy to use but, would be nice to try and get it to work without - bigger capacitor to hold the reset line low until the supply comes up? 

Happy to help try and get to the bottom of this.

 

I guess it will depend on where you bought it, a lot of people use PCBway but there are some that use other PCB manufacturers. Let us know how you go with the capacitors, thanks!

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13 hours ago, Frankensteinowner said:

Thanks Terranigma - I'll be going into the office on Friday to change the cap - I'll put a 1uf in its place to hold the reset low wile the supply comes up.

 

Thanks for the update. If the 1uf gets it working, and I know it's a bit more stuffing around but would you be able to swap in another new 100nF cap to see if the original one was faulty if you have one?  Good luck and thank you.

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I took the board into the office today and connected it to a bench supply set to 18V - observed the reset line on a scope - waveform was as expected though the device didn't restart. Pressing the reset button restarted the display correctly.

I removed C2 and measured it as 111nF and fitted another 100n - the unit still wouldn't restart automatically on power-up.

I fitted a 1uf and the rise time was extended as expected however, the device didn't reset without  manual intervention.

I did measure the voltage of the 3V3. It looks as if R23 has been manually replaced on the board with a 4K7 (the board is marked as 3K9) - the supply voltage was 2.66V @Lucky -  Is this as expected or should it be pretty close to 3V3? I measured the 5V at the red and black cables that go to the display modules - these were just over 4V.

I tried fitting a 3k9 this raised the 3v3 to about 3V however, the board still wouldn't self start so, I returned the resistor the 4k7 where there line returned to 2.73V but, it still won't restart.

Peter

 

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2 hours ago, Frankensteinowner said:

I did measure the voltage of the 3V3. It looks as if R23 has been manually replaced on the board with a 4K7 (the board is marked as 3K9)

Hey Peter, thanks for the testing and the results. Was hoping that would solve it but I guess something else is going on. Will have to see what Lucky says.

In regards to R23 did you mean R32? This was changed to be compatible with an issue with new models of the P2 display panels. If you had an old board with the old resistor then you would have to manually change it yourself to ensure compatibility with the new display panels. The old resistor was in fact 3K9 but the new panels require a 4K7.

The boards have been updated now so this only applies to older stock.

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Sorry - my mistake - was R32 - looks like it sets the output voltage on switching regulator. @Lucky1 - are you able to provide any info on what the limits of the 3V3 rail should be - mine does seem very low at 2.66V - maybe this is why the board doesn't start correctly? (it runs fine once reset - I'm very pleased with it).

Peter

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10 hours ago, Frankensteinowner said:

Sorry - my mistake - was R32 - looks like it sets the output voltage on switching regulator. @lucky1 - are you able to provide any info on what the limits of the 3V3 rail should be - mine does seem very low at 2.66V - maybe this is why the board doesn't start correctly? (it runs fine once reset - I'm very pleased with it).

Peter

Hey Peter, I will check my boards for the 3V3 rail voltage as well this afternoon and see if there is any difference between a working board and a board that doesn't boot properly and let you know. 

So far you have ruled out C2 being the issue, if the 3V3 rail is acceptable as well then we will need to check elsewhere. I will do the test and get back to you guys. 

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I just measured a bad board vs a good board. Ok so both boards when they boot show 2.66V on 3v3 rail. When the bad board doesn't boot it shows 3v+ every time. So I am not sure if that has anything that can help identify the issue.

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28 minutes ago, lucky1 said:

I measured on a EVO without panels connected and have 3.3V right after the 2940CP33 and 2.98V after the BAT60J

I tested the 3v3 pin at the SWD pin header with an EVO without panels to get the above results.

I will check after the 2940CP33 and after the BAT60J on the faulty board and post my results. This is on an Evo 128x32

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I have 3.3V right after the 2940CP33 on the faulty board AND working board.

I have 3.05v after the BAT60J on the faulty board and I have 2.98v on the working board.

It seems the faulty board is 0.07v higher after BAT60J but when the faulty board boots and works it drops down to 2.98v

The other thing was that when I was measuring on 2940CP33 touching the pin on that chip with the multimeter (the far left one) it caused the faulty board to boot. Touching it again made it turn back off.

 

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Thanks guys

Can one of you confirm what voltage you're getting out of the switching regulator - I understand the R32 change was to drop this but, what should I be seeing here? The BAT60 appears to be in series with the output of the 3V3 regulator - Lucky - do you recall if this was to deliberately drop the 3V3 or is there another reason for it?  I'll look up what the dropout voltage is on the regulator too - if I've only got about 4V going in, the regulator may be dropping out.

Sounds like Lucky has a much higher voltage at the regulator output than I have. If one of you guys can tell me what the 5V should be, I may adjust the R32 to see if raising this brings up the voltages and hopefully, the unit will reset properly (if not, I'll just build a little astable to hit the reset button a second after the power comes up. 

And my modules are different colours - is this what I need: https://www.ebay.co.uk/itm/LED-SIGN-P2-5-PH2-5-64-64-Pixels-Dot-RGB-Full-Color-LED-Module-Board/402638418786  

Is £28 each a fair price?

Thanks both for your help so far. 

 

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Voltage is set to 4,17V  with R32 = 4.7k  but I´m pretty sure that is not the root of your reset problem. 
How do you power your display. The internal 18V at the molex connector should work fine.

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19 hours ago, lucky1 said:

I measured on a EVO without panels connected and have 3.3V right after the 2940CP33 and 2.98V after the BAT60J

Are there any components that would cause me to have 3.05V after the BAT60J instead of 2.98V when it won't boot?

It has 2.98V after the BAT60J when it does boot. Only has the higher 3.05V when it won't.

 

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29 minutes ago, Terranigma said:

Are there any components that would cause me to have 3.05V after the BAT60J instead of 2.98V when it won't boot?

It has 2.98V after the BAT60J when it does boot. Only has the higher 3.05V when it won't.

 

I guess that is simply the CPU not running.

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