Sammichsid : Problems with FW / Banksticks, **FIXED**

[lazerbeat]

This is my first ever electronics project so I am amazingly happy I have made it this far without running into any issues but I have a problem and I am not sure where to start diagnosing it. Also I am a totally new builder, haven't made anything like this before so please feel free to point out things which may well be blindingly obvious to you guy.

Thus far I have,

- Completed all soldering

- installed shunts

- Voltage checked several times.

- Everything looked good so I installed all ICs except the SIDs and the Banksticks

- Uploaded "setup_sammich_sid.hex" from "the V2.0rc36" zip using "MIOS beta 9.4" all seemed fine. Upload control window gave an "ok" message

- System rebooted into boot screen then the main screen.

- All seemed fine, tested all 12 buttons and the rotary encoder all seemed fine.

- Installed bank sticks and SIDs (with caps)

- Powered on, sammichSID beeped seemingly randomly a few times, LEDS flashed in a kind of hexagonal pattern similar to when it first rebooted, top line of screen is solid black boxes, bottom line is blank. It most certainly did not show a screen indicating the banksticks were being formatted.

F1 key and F3 key responded by lighting a few of the LEDs and causing wierd random beeps. all other keys are dead.

If I power of the machine and restart it, sometimes it returns to the above state immediately, other times it will go to the default menu screen. While its at the default menu screen, I can get the midi messages to go to LCD via the "MIOS LCD message" function but if I press any buttons on the sammich it will lock after a few seconds.

I am really not sure how to proceed from here, any help would be much appreciated

[Wilba]

It sounds like it was OK, then you took the CS board off and installed chips and when it was put together again, you have LCD and switch problems.

Or possibly voltage issues, now that you're powering two SIDs.

SO I would say, revert back to the way it was first. Take out the SIDs and 24LC512 ICs (I would suggest numbering the 24LC512 ICs with a pencil so you can put them back the same).

Also check you have the shunts set correctly for the high-power LCD and turn the brightness knob to minimum. This will help you assess if it's a current draw problem.

Upload firmware again (with CS PCB removed!) to be sure the PIC is still working and that you SHOULD be seeing stuff on the LCD.

Then you can reassemble and it will probably work again. Then you can see it stop working by increasing the LCD brightness and/or inserting the SIDs, and then prove it's a current supply issue and not anything to do with shorts/breaks/bad joints.

[lazerbeat]

Thank you most kindly for all your advice. I still haven't been able to fix the problem but I have made a fairly significant amount of progress.

This is what I did.

- Removed CS

- retested voltages - all ok

- rechecked shunts - all ok but one could have been pushed down a shade further (which I did but I think it was ok)

- Reuploaded hex file - all ok

- connected CS, all buttons functioned perfectly!

- removed CS, inserted banksticks

- powered on unit, didnt get a "bankstick formatting" message

- successfully uploaded default patches from bank library, all visible on the unit.

This is the problem

- Installed SIDs and Capacitors and the screen locks on boot with the row of black squares at the top and no functionality after the LED array flashing and a few kind of "welcome sound" style beeps.

- to double check I removed the SIDs and caps immediately and reconnected the CS, everything worked perfectly.

I have double checked my shunts and capacitors, I also rechecked my voltages, I am acctually getting a consistent 8.91

instead of 9v but my multimeter is old and cheap, I doubt it is perfectly accurate.

I don't know if I have messed up somewhere or my power supply isn't correct or I have damaged this sids but a little more help would be most welcome.

Thanks so much!

[Wilba]

Excellent reporting, I wish everyone would describe their troubleshooting like that!

I can't be exactly sure, but it sounds like adding the SIDs causes the current draw to be too much for the supply, the 5V supply sags just enough to make the PIC->LCD comms fail on startup, but otherwise the PIC boots OK and the LEDs flash etc.

Try inserting just one SID, maybe you have enough supply for the one, and you can actually get control surface + SID working and prove that everything SHOULD work (i.e. the SID isn't strangely interfering with the rest of the circuit).

Try also REMOVING the shunt in JBL. This will turn off the LCD backlight completely, removing more current draw from the system.

I also suggest you check your plugpack rating... maybe you are using something insufficient.

i.e. is it 12V AC 500mA or 12V DC 500mA etc... quote all three values, the voltage, the type (AC/DC) and the max current.

[lazerbeat]

Heh, thanks very much for the compliment and the continuing help. Tried a few more things.

Here is the information from my power supply.

Output - DC, 12v, 1A

Its a switchable unit I took a picture of the label ( http://twitpic.com/1ciq7c ) and the back of the unit ( http://twitpic.com/1cj0ix )

I also tested the following

- Tested the voltage of my power supply in 2 different sockets (1 wall socket, 1 in my power strip) both 12.21v

- Installed one SID chip (in the slot closest to the pic) and the 2 caps - Screen locks on power on

- Removed JBL shunt, one SID chip still installed - Screen locks on power on

- still with the shunt removed, exchanged the sid chip just incase - Screen locks on power on

Things now get a little more interesting

- Removed the sid chip and the caps to test in the original configuration and now the screen locks with no sid chips installed at all. Sometimes it locks on start up with the top row of squares back, sometimes it locks (kind of like the screen is frozen like a windows crash) after pressing a button, sometimes it is ok for a couple of minutes then the screen locks.

- Tried adjusting the trim pots to various positions, same problem.

The only part of the construction when I might have deviated slightly (that I am aware of) is the connection pins between the CS and the main board to the left of the LCD have about a fingernails width between the male and female connectors. I found the male pins very difficult to solder.

Must admit I am really a little confused here. I have obviously gone wrong somewhere but not sure how.

[lazerbeat]

More very hopeful information. I believe I have solved the problem!

Wilba's very helpful advice suggested the power supply might be the problem. I went into town and picked up a slightly meatier non switchable power supply

DC - 12v - 2A

And everything seems absolutely fine! I had the machine on for long enough to run through the preset patches and get hopelessly lost in the menus (haven't read the manual yet).

I would like to ask a final question. It the more powerful supply likely to damage the sammichSID or blow any caps/melt the SID chips or anything? Based on what I have read the system will only take as much power as it needs but I would like to check.

If this is no problem (and assuming the system doesn't blow up or melt or anything) I will consider the problem solved and thanks once more to Wilba for the comprehensive advice.

Would someone be kind enough to edit the topic title to:

"Problems with FW / Banksticks, [solved, power supply issue]"

or something similar?

Thanks alot, now to write some tunes!

PS, hope you enjoy your beer.

Edited April 2, 2010 by lazerbeat

[Wilba]

Beer enjoyed *glug*

The current rating of a power supply means how much current it can deliver at that voltage. If the power supply is unregulated, then when the current draw is at the maximum, the voltage also will be about the same. i.e. for a 12V 2A supply, the voltage will be 12V or more when the current draw is < 2A.

However, this can lead to the voltage being quite high when it goes into the regulators on the PCB, which means the voltage difference between the input and output of the regulator is higher than it needs to be. This voltage difference needs to go somewhere, and it is turned into heat, which is dissipated out of the heatsinks. I know sammichSID has enough heatsinks and ventilation for up to 12V DC going into the 7809 voltage regulator (i.e. 3V difference, times max current draw of 500mA). Anything higher than that should be avoided - it will generate more heat than can be dissipated by the heatsinks (IMHO). I'm no expert, I just experimented until I was happy with how hot the heatsinks became (or rather, how hot they didn't become).

I recommend checking the voltage going into the 7809 (i.e. the point labelled "12V" on the PCB) when you have everything connected. That's a bit hard to do with the sammichSID fully assembled, I'd suggest taking it apart and assembling just the PCBs together and measuring on the bottom of the base PCB. This will give you a true indication of how "safe" your 12V 2A supply is... if the voltage is 12V-14V then that's probably OK, but if it's anything higher then you'll need to think about getting another PSU (sorry) or working out why the 12V 1A wasn't good enough... it really doesn't make sense because the 12V 1A should be OK. Compare the two supplies.

Also you should see how this voltage changes as you change the LCD brightness.... when the JBL header is set to "12V", the current is taken BEFORE the 7809 regulator so the voltage will be LESS going into the 7809 than if you disconnected the LCD. Similarly, the LCD brightness trimpot will have an effect on the current, and thus also the voltage.

SO.... do voltage tests on the "12V" pin, with BOTH PSUs you have, with everything installed, at three different brightness settings (fully anti-clockwise, middle, fully clockwise)... note also which combinations result in fully working LCD/control surface.

To give you some helpful insight... I have a red/black LCD that only works (with my 12V AC 500mA supply) if I set the brightness to middle position, any higher and the PIC doesn't boot and the LCD stays in "black bars" mode. I can actually watch it drop out (i.e. PIC reset, go to black bars) as I turn the brightness. I think you could possibly do the same thing with your setup. However, it doesn't make sense why your 12V 1A supply can't deliver the 500mA maximum current draw of a fully loaded sammichSID with a "high-power" (~250mA) LCD backlight. Doing the voltage tests might help diagnose what is really at fault... you might find it's better to use the 1A supply with the brightness at minimum, than the 2A supply (better in terms of the 7809 input voltage being the lowest possible).

[lazerbeat]

Thanks once again for the continuing help. I must confess to being slightly confused, the sammichSID now seems to be working with both power supplies... Obviously random hardware wierdness is never a good thing and I would like my synth to be as stable as possible but I appreciate it is a bit of an annoying and elusive problem...

I did perform the tests you mentioned, I hope the are helpful.

Results of tests

----------------

All tests probe the lower right ground point (black probe) and the 12 V leg of the voltage regulator (red probe). The contrast knob was just a shade clockwise from all the way anti clockwise, is the furthest clockwise it could co and still be visible.

- 12v, DC, 2A adaptor - New Adaptor (non switchable)

Brightness fully anti clockwise - 10.47 or 10.48 (fluctuates slightly) - Fully working CS

Brightness 12:00 oclock - 10.47 or 10.48 (fluctuates slightly) - Fully working CS

Brightness fully clockwise - 10.46 or 10.47 (fluctuates slightly) - Fully working CS

- 12v, DC, 1A adaptor - Older Adaptor (switchable)

Brightness fully anti clockwise - 10.46 or 10.47 (fluctuates slightly) - Fully working CS

Brightness 12:00 oclock - 10.48 or 10.49 (fluctuates slightly) - Fully working CS

Brightness fully clockwise - 10.49 or 10.50 (fluctuates slightly) - Fully working CS

[Wilba]

Based on that data, both these PSUs must be regulated 12V output. Therefore you'll get a constant voltage regardless of current draw... so it's safe to crank the brightness up as much as you like, as that current is taken before the regulators/heatsinks.

The only part of the construction when I might have deviated slightly (that I am aware of) is the connection pins between the CS and the main board to the left of the LCD have about a fingernails width between the male and female connectors. I found the male pins very difficult to solder.

Must admit I am really a little confused here. I have obviously gone wrong somewhere but not sure how.

Can you post a photo showing what you mean by "a fingernails width between the male and female connectors"?

It's possible your problems are/were intermittent contacts between the LCD/CS and the base PCB.

It only takes one data bus contact on the LCD connection to be faulty and the LCD will not receive the correct initialization and stay in "black bars" mode.

I advise resoldering the connectors, but let me have a look first to see how yours is different and if that could make a difference regarding reliable contact etc.

[lazerbeat]

Can you post a photo showing what you mean by "a fingernails width between the male and female connectors"?

I have a feeling this may have been the problem all along. I found the pins next to the LCD most difficult to solder so they are not as close to the baseboard as you recommended. I would guess that screwing CS down and adding the case perhaps squeezed the contacts together a shade more.

Here is the picture and once again really appreciate all your help and very sorry if I led you in the wrong direction trying to troubleshoot the problem

http://twitpic.com/1d43pv

[Wilba]

Yeah that might be the cause of LCD weirdness. It's hard to see the gap on the 2x5 header though.

If the LCD becomes intermittent, you can try putting washers between the LCD and the CS PCB to lower it by 0.5mm or so, this might be easier than resoldering the header.

[lazerbeat]

Yeah that might be the cause of LCD weirdness. It's hard to see the gap on the 2x5 header though.

If the LCD becomes intermittent, you can try putting washers between the LCD and the CS PCB to lower it by 0.5mm or so, this might be easier than resoldering the header.

I think it might have been, since screwing everything down my sammichSID seems to be behaving correctly. I will consider this fixed if you don't mind and thanks once again for all your help.