ELATION Magic 260 not powering up

[Brian]

There's something very wrong with your measurements. On the 7705 pin 4 should be connected to the 0V rail and not be some random voltage.

[Brian]

 

So U9 contains the program memory. 

[indyld]

On the 7705, with RESET low and ---RESET high it appears the IC isn't permanently sending a reset signal. Hopefully it sent one at startup though. While looking at this part of things I would also check the connected reset pin at the micro just in case this proves instructive (unlikely) and also in some cases I've forced a reset by shorting stuff out with my tweezers. Of course, the ideal first step in all of this is to check the mcu is actually running at the clock. I can't recall if I've been successful trying a multimeter set to Hz for this but it seems unlikely, these days I have a cheapy pocket scope for such things. 

 

Meant to say, as Brian mentioned, it looks like you may need to find a better GND when taking voltage readings. Pin 4 should definitely read 0.0. I usually use a nearby ground end of an MCC, obvious -ve of an electrolytic, or on a lot of boards the main casing of a USB or other connector. A screw hole connected to a ground plane is also a classic.

Edited June 6, 2022 by indyld

[partyanimallighting]

Brian, indyld, I took readings again. The first readings were taken with the - meter lead connected to the TIP41 heatsink on the main input PCB (I thought this would be fine as I assumed that a common ground would be fed through the ribbon cable). So I tried again, connecting the - meter lead to the heatsink on the TIP42 but I did not get continuity from the heatsink to pin 4 on the 7705 so I connected again to a tested ground which gave continuity back to pin 4 on the 7705 and pin 20 on microcontroller. I'm really sorry about this but I am still learning a lot about circuits in general and I should have tested for a proper ground instead of wasting all of your time. Fortunately, every day I learn a little more, thanks mostly to help from you guys. Anyway, I hope you can accept my my apology and I've relabeled everything that was tested and here are the new readings for the 7705 and the microcontroller. Obviously, I made a mistake connecting to the TIP41 initially but can you explain why the readings are different? Would there not be a common ground fed from the input PCB to the control PCB via the ribbon cable?

[DrV]

[QUOTE]Obviously, I made a mistake connecting to the TIP41 initially but can you explain why the readings are different? Would there not be a common ground fed from the input PCB to the control PCB via the ribbon cable?[/QUOTE] The tabs of neither the TIP41 nor the TIP42 are connected to 0v. A good place for a ground connection would be the tab of the 7805 which is 0v. Usually the tab is the collector of TO220 transistors. In the case of the NPN TIP41 the emitter is connected to ground and the collector goes to the backlight. In the case of the PNP TIP42 the collector probably comes from the 5v rail and the emitter goes to the usb/lamp connector.

Edited June 6, 2022 by DrV

[partyanimallighting]

Drv, I understand now. It's all in my learning process and I'll be more careful in the future and I'll check for a definite ground before taking any more readings.

[indyld]

OK, so I guess the new question is the next strategy for diagnostic. If U9 is flash memory, then the traces look like they are connecting TO the parallel bus, not organising it. Microcontrollers etc. is more for Tim and others really, but I guess that perhaps the parallel bus (that also connects to other key parts of the board) is being output at the MCU I/O Port 0, bottom left in the image?

If a screen output is not being sent, does this also mean that the bus isn't doing anything useful at all? This is why I was asking if any other stuff seemed to work (buttons latch LEDs etc). I suspect not, so I guess the next question is the best way to verify the MCU with limited facility. At this point, it's great when you have another known working unit for comparisons or parts swaps, because once past the checks of power, ground, enable/reset pins, clock activity, then I'm running short of ideas for a diagnostic next step in this area without some kind of additional lead such as the failure story details, physical stuff or whatever.

Are we now in the land of the already mooted 'EPROM gone loopy'?

Edited June 6, 2022 by indyld

[partyanimallighting]

Yes indyld, the next strategy for analysis it is. What are your general findings on the new (CORRECT) voltage readings? Does the 7705 and microcontroller appear to be functional based on the readings? As you said, it would be great if I had another working unit but that'll be hard to find locally. Am I to assume that the QFP chip SST29SF040 (U9) which I can source online can be replaced and just popped in and this would not have to be preprogrammed whereas the microcontroller would be proprietary and preprogrammed from Elation and I'd have to contact them and hope for the best? Their support for older or discontinued units is relatively non-existent. Now, just assuming that I did have another working unit available for testing purposes what would be your approach? Would it be to replace the SST29SF040 and power up to see what happens and, if the problem is still there, then replace the microcontroller and repeat the process?

[DrV]

Other way round - U9 contains the program so would need to be programmed, the processor is just a microprocessor (not strictly a microcontroller) so could be swapped. I'm not convinced it is a 6502 - I thought they were much slower than 24MHz. More label peeling required, or did I miss the part number earlier?

As for further investigation it becomes more difficult without a 'scope. However, if you could find someone with a similar unit it would be possible to read the contents of U9 and copy them into a new, blank chip. No copy protection issues as there usually are with microcontrollers. It could be a faulty logic chip, and there are plenty of those on the board, but diagnosing without a 'scope is not really possible.

The voltages on the 7705 are ok except for pin 2. Are you sure that's low? According to the datasheet it's /RESET (Reset negative true) input so I would have expected it to be pulled up or tied to pin 8. The outputs look correct but with a meter you wouldn't see any tiny spikes on them.

Edited June 7, 2022 by DrV

[partyanimallighting]

Hi Drv, as requested, label peeled. I also retested voltages on the 7705 and all the readings are the same except for pin 2, on which I got a reading of 5V. From the datasheet for the 7705 I saw that it sends intermittent voltages and I'm assuming that this is for the actual booting up of the console but I saw no spikes on my readings when the controller was switched on and off. Maybe I was doing something wrong or as you said it would not show up on a meter. It seems that this investigation to repair is winding down unless I get a hold of another working unit and it makes no sense to buy a used one (2 available on eBay) for 200 bucks just to find out what's wrong with this one. I don't want to waste more of your time so let me know if you think I should close this case and file it under UNSOLVED and toss the unit back in storage until another working unit turns up or falls out of the sky.

 

[alistermorton]

That's a 40MHz 8051 compatible. Flash programmable 32K ROM. I suppose it might have forgotten its program. I wonder if U9 is the NVR?

[timsabre]

U9 29SF040 is flash, I would think for user programmable storage. Device firmware will be in the micro.

I would check the reset for the processor (PSEN on pin 29). This should be low on power up then go high. If this is not going high then the firmware will not run.

[DrV]

Pin 9 is RESET. It should go low just after the oscillator has started up, but again, you'd need a 'scope to check the timing of that (unless it's stuck high). I think that's me out of ideas with this one, sorry, but if anything else pops up I'll be interested to join in again.

Dave 

[timsabre]

Doh yes you are right. On 8051 reset is active high so it should go high on power up then low, not what I said above.

[partyanimallighting]

Hi,

I have a non-functional Magic 260 which, upon power up, has a flashing 
top character display line and nothing else. Nothing is functioning 
and I believe that either the W77E058A40DL MicroController and/or the
SST29SF040 is faulty. Are these parts available, fully programmed, ready for installation and startup and at what cost?

Renato

 

Hello Renato,

What happens if you press and hold function buttons 1, 10, 20 and 24 then turn the unit on?

Best Regards

Kevin C Picard (KC)
1800-322-6337 EXT 754
323-316-9754
Fax # 323-582-2941

6122 S. Eastern Ave
Los Angeles CA. 90040

http://www.americandj.com/
http://www.adjaudio.com/
http://www.elationlighting.com/
http://www.globaltruss.com/

Hi Kevin,

     I posted the problem in some forums and someone suggested that but it did not work. The top character row of the display kept flashing and nothing else functions.

Renato

 

Sorry to hear that was our last hope as we do not have parts for this unit any longer. Let me know if you have any other questions and have a good day.

Best Regards

Kevin C Picard (KC)

1800-322-6337 EXT 754
323-316-9754
Fax # 323-582-2941

6122 S. Eastern Ave
Los Angeles CA. 90040 

http://www.americandj.com/
http://www.adjaudio.com/
http://www.elationlighting.com/
http://www.globaltruss.com/