Trying to fix my sammichSID

[missingsense]

My sammichSID has been broken for quite some time now, and I really want to get it back working. I don't have a lot of experience in tracking down what's the problem, so I thought I'd ask around.

 

It was working fine until I decided that I wanted to use the low power Optrex STEP LCD instead of the stock high power LCD. (Jason had previously sent me one, because of some issues during the build, but I never used it).

 

After I set everything up, made sure all the jumpers were correct, it didn't show anything on screen, but the audio was still working and I also still had the LED animation. I asked around, and it was probably the PIC that needed to be replaced. After I replaced the PIC with a fresh pre-burned one and connected it with MIOS, I uploaded the latest software, aaand nothing. No LEDs and no sound. I misplaced the previous PIC so I don't know if it's the MIOS not uploading correctly. It says it uploaded correctly. But nothing happens when I reboot. I occasionally see a really short flash of leds lighting up when I switch it on.

 

The only thing I found out later was that I had the polarity on the power supply the wrong way around (I had it set to center negative), which apparently works fine with a high powered LCD and 8580 chips, but might be wrong when using a low powered one? Could that be a good assumption? Could that also lead to finding out what part I might have blown?

 

[Imp]

The polarity of the supply doesn't matter, as there is a rectifier right after the plug.

I'd start with checking voltages anyway. Pull out the PIC and SIDs and measure voltages at the sockets.

To determine where to measure, you can refer to the schematic of  the base-pcb, which is in the wiki.

[missingsense]

Thanks, I'll try that.

[missingsense]

Okay this took a while, I had to replace my multimeter.

 

I measured the voltages in the sockets as shown in the build guide. They all give 5V as they're supposed to, so that seems ok. Are there more points I could measure based on the base-pcb? I had a look, but I don't know what I'm looking for. I can only find the ground points, and I can recognize the 5V points because I know they are there based on the build guide.

[Imp]

You can go on inserting ICs one by one, measuring voltages in between. If voltages change, you know the cause.

Does it respond to MIOS-studio without SIDs and Display (just PIC and all of the small ICs)?

[missingsense]

Alright, thanks a lot. I think it responds to MIOS studio just fine, at least it connected and I could upload and it told me everything went well. Except no reboot etc.

 

I'll go investigate in the morning.

[C_04]

Hi

Always what i do in such cases - back to this point when something been working. Replace LCD with this old one to check that in this configuration everything is still working. Reason could be contrast pot.

Cheers

C_04

Edited August 9, 2014 by C_04

[missingsense]

True. That's the first thing I tried, and it didn't work; which led me to believe I fried the PIC. but the other thing is that all the LED's stopped blinking on start up as well. The screen still gets powered, I can see it lighting up. But it seems there's no control.

 

I still have to check those voltages with the PIC installed, but should I remove all IC's and measure everything? I didn't actually remove the smaller ones before, or the memory sticks, just the big PIC and the SID's.

Edited August 11, 2014 by missingsense

[C_04]

Only PIC and LCD should tell you they working. So remove all other ICs. Once i had problems with fried 595 shift registers - they were big short for entire circuit. Another reason could be crappy sockets and its possible because you said that PIC is responding for MIOS other thing - bent legs.

Cheers 

 

P.S. I would also suspect bad connections via connectors MAIN PCB vs CS PCB. Bad soldering points are also possible. No blinking/disco leds may be just because differences in software or wrong software/incomplete.

Edited August 12, 2014 by C_04

[missingsense]

Okay so I removed all the ICs except for the banksticks, and inserted the PIC. I switched it on and tried to measure voltages, but there was nothing. Not even 12V on the power switch itself. scratch that, this was just a bad connection from the power supply I was using; I was using a different one and the head of the plug was too big which caused intermittency.

 

When I remove the PIC I measure the correct voltages again.

 

Also, when I insert all the ICs except for the SID I get the correct voltages. So that's probably nothing.

 

I tried connecting with MIOS without the LCD and SIDs but it's not working anymore..

Edited August 17, 2014 by missingsense

[missingsense]

Okay I could get new 595 chips then. Is that a good next step? I believe all the voltages measure correct, the pins aren't bent and the sockets and solder points are all fine. Could there be something else I should check?

 

Should I try and reburn the PICs? The guy that burnt them for me offered to do it, he told me that might be the problem.

 

Did I mention the fact that I soldered two wires to the bottom of the board in order to give the Optrex LCD the current? Could this have been the error? I've included pics of the mod here:

 

https://dl.dropboxusercontent.com/u/3429552/2014-08-19%2003.00.53.jpg

https://dl.dropboxusercontent.com/u/3429552/2014-08-19%2003.01.34.jpg

[Hawkeye]

Hm, why was that display mod necessary? No backlight otherwise? Don´t know the sammiches, but this looks strange to me :) Could you remove the wires for a test?

 

Many greets,

Peter

[missingsense]

The header for the Optrex is different from the standard Display. They are both 16 pins, but the pins for power are at the bottom instead of at the top. And the header is shifted 1 down in comparison to the normal LCD. At least that's what I got out of it. It's really a longshot though. those pins are unconnected on the PCB otherwise.

 

I'll give it a try, unless someone can confirm this is ok.

[Shuriken]

I assume this is the datasheet for the Optrex Step part. The power for the backlight is indeed on pin 1 + 2 instead of the normal 15 + 16.

 

But did you do anything else to mod it? How are DB6+7 on the lcd connected to the datalines on the Sammichsid base pcb?

[missingsense]

No, I looked up the email from way back, here's the bit about the Optrex:

https://dl.dropboxusercontent.com/u/3429552/Screenshot%202014-08-19%2022.15.53.png

 

Could the second wire I added be the cause of my problems? I'm going to remove it anyway, but it's just the grounds, right?

[Hawkeye]

Hmmm, as long as you install the Optrex display so, that Pin 1/2 are plugged into the pins connected with your wires, all should be well (Shuriken: the whole display pin connection is moved by one step) - did not know that Optrex speciality pinout! No need to remove the second ground wire, but no harm uninstalling it, as it is connected to ground already (see the PCB in your last dropbox upload).

 

Many greets,

Peter

Edited August 19, 2014 by Hawkeye

[C_04]

If you can please show us also CS for this sammichSID. I wanna be sure that you not doubled B+ pin. 

Dont change 595 if nothing bad happening.

Cheers

[missingsense]

Alright here are a bunch of shots. Last one is the header of the old display.

 

https://dl.dropboxusercontent.com/u/3429552/2014-08-20%2012.22.25.jpg

https://dl.dropboxusercontent.com/u/3429552/2014-08-20%2012.22.35.jpg

https://dl.dropboxusercontent.com/u/3429552/2014-08-20%2012.23.34.jpg

https://dl.dropboxusercontent.com/u/3429552/2014-08-20%2012.23.54.jpg

[Shuriken]

I had been looking on this schematic, the extra holes are probably from a later revision. So i did not notice.

 

No, I looked up the email from way back, here's the bit about the Optrex:

https://dl.dropboxusercontent.com/u/3429552/Screenshot%202014-08-19%2022.15.53.png

 

Could the second wire I added be the cause of my problems? I'm going to remove it anyway, but it's just the grounds, right?

 

No, it's not ground. It could very well be you killed T1 with the extra wire.But since i don't have the schematic of the new revision i am not sure. But since T1 is responsible for the current flow to the backlight, it's a likely suspect.

 

I would remove the extra wire and my guess is you need to replace T1 (BC337). But you could check first.

Edited August 20, 2014 by Shuriken

[C_04]

First at all. Do you have any backlight? Measure these 2 pins where you soldered wires. Im not sure where there is connected transistor but probably to B-. So there should be ground potential when transistor is short and you can remove this transistor and solder there maybe 300R resistor. Second pin you have connected wire to B+ should be 5V and measure that. All measurements make to ground: B- to gnd = short; B+ to gnd = 5V. Or something like that. Thats what you have to be sure to get LCD baclight. Any reasons are: pins swapped, broken LCD led, your connected wires are shorted to gnd. Measure and if there no 5V then try to find where is the closest point you can find it. Maybe as Shuriken said: you fried T1 (im not familiar with proper row order they numbered). You can even remove entire CS and put legs from any LED inside these pins you soldered some wires (lower than 1, 2 and 15, 16). Maybe add here 300R resistor in series with your led. Now you should know that you have backlight voltage and there is enough current to light it up. You may also try the same with yours LCDs. In optrex connect 5V to pins 1 and 2, to this older 15 and 16. Cell phone chargers often use lower than 5V and it will ok for your test - thats in case you not have any power supply. Otherwise you may use sammichSID power supply but add in series with your LCD led something about 1k. I dont know you have there any resistor already soldered. 

Please check your blue wire is that shorted to the ground. Looks your problems started before mod. So we have to try something different. Try maybe that sammich is responding for midi - i mean that you can play any sounds. 

Cheers 

Edited August 21, 2014 by C_04

[missingsense]

I should have just copied the whole message. Sorry about that..

 

As for the backlight, it still works fine. Right after I got the PICs I still could, and had (repeatedly) uploaded the sammichSID.hex - but nothing seemed to happened. After a reboot I couldn't see anything on the LCD, it didn't make a sound, and the LED's didn't do their startup pattern.

 

I ordered two PICs, had them both burned by someone else, and I tried them both. Same thing on both cases.

 

Right now I can't connect to MIOS anymore. And I've also tried both PICs..

 

Could it be the PICs themselves?

 

 

Anyway here's the text I got from Jason many moons ago. Thanks for the patience all, I will noob my way through this..

 

New PCB Revision 3

 

This batch includes revision 3 PCBs, the only differences are slightly different silkscreen (the white printing) and the J16 header, which is still technically 16-pin but you can use an 18-pin header. This allows people to (optionally) use the Optrex STEP LCD, which has the backlight pins (B-, B+) at the other end of the header, the two pins NOT in the outline. (I used the same solution in the sammichFM design).

 

For everyone using a negative green (the default LCD) supplied by me, just put the male header in the 16 pins closest to the top of the PCB (i.e. closest to the rear panel/sockets).

 

If you're using an Optrex STEP LCD (i.e negative blue), put the male header in the 16 pins closest to the bottom of the PCB (i.e. closest to the J8/J9 female header).

 

If you're using an Optrex STEP LCD, you must also solder one wire on the bottom side to connect the B+ pin to the unmarked pad at the bottom, on the same side.

 

Unlike sammichFM, there are no tracks, you need to use a wire. Sorry for the inconvenience. Optrex STEP LCDs are considered "low power" so follow the build guide instructions for "low power" LCDs (JR4=open, JBL=5V, brightness pot=max)

 

There's only one way your LCD can align and fit (when mounted to the control surface PCB), so don't worry too much about it unless you plan to connect the LCD while it is not mounted to the control surface PCB (which you probably should never need to do).

 

 

[Imp]

Right now I can't connect to MIOS anymore. And I've also tried both PICs..

 

That's where you need to start.

Possible reasons for this behavior:

-wrong MIDI-ports in MIOS studio

-MIDI-interface doesn't work

 - >these can be ruled out with a loopback-test

 

-Optpcoupler on the sammich doesn't work

  ->MIDI-in of the sammich doesn't work, so no upload, query etc. If it boots properly, it will still report once in MIOS-studio.

 

-PIC doesn't work

[C_04]

I think you should check all ICs that you assembled them correctly. Check that maybe you have bad soldering points - its possible because you removed and installed ICs and that was enough to stop working entire device. Check that all legs are sitting properly in sockets, try squeeze once again each ic into socket. In Pic socket find gnd pins and measure voltage to 5V pins - all inside the same socket. Check oscillator is soldered well. After powering on your sammich are you able to see a belt in upper row (cursors row). When CS instaled check whats on lower pins signed gnd, 5V (RS and any digital is impossible to measure using simply voltmeter). After you open MIOS Studio do you see any initiations from sammich? It should be still something there even if optocoupler is not working. Dont swap cables - sammich is sending that via MIDI OUT.

 

 

P.S. To me first steps here would be to check contrast pot and set it to see belt of cursors on LCD when sammich is starting. Second - to be sure system is working. And hehe i must say that it would be easier to repair it by myself than do it via online;) Price of these 2 PICs could cover all shipping costs but now you already have them. ;)

Edited August 22, 2014 by C_04

[missingsense]

Alright had a busy month, but I sat down with it just now.

 

* the LCD on the control surface lights up, I can see two rows filled with blocks.

* the LEDs do nothing.

* when trying to connect with MIOS I get the following:

 

pressing 'Query' responds with: "No response from MIOS8 or MIOS32 core!". I do get 5 SysEx strings responding from the sammichSID containing: "f0 00 00 7e 40 00 0e 03 32 f7"

 

I do get a steady pulse from the sammichSID. It contains a SysEx string with "f0 00 00 7e 40 00 01 f7". I also get similar responding SysEx strings when I'm uploading the hex file. There is some form of communication, but the core doesn't seem to respond.

 

trying to upload the sammichSID hex gives: "WARNING: no response from core". It then proceeds to send the data anyway, responding with SysEx strings. After the process is complete it just continues with giving the steady pulse of "f0 00 00 7e 40 00 01 f7"

 

* Minor detail I noticed. When I turn the sammichSID on or off, with the control surface attached I get a "f0 f7". When I remove the control surface I get a bunch of lines when I turn it off. "fc" and 5 or 6x "ff" on seperate lines.

 

* I tried both the PIC chips I had burnt, both the same result.

 

Suggestions? Should I get a new optocoupler? Try and get the PICs reburnt? I believe the soldering is all sound. I checked everything, and it worked without a hitch before I did the "optrex surgery" (soldering in those two wires), I probably should have removed all the ICs before I did that. Maaaaybe?

 

Please help guys, I really miss using this little box..

 

Edited September 11, 2014 by missingsense

[missingsense]

Okay searching for "f0 00 00 7e 40 00 0e 03 32 f7" on google I found that the MIDI on the device I was using to connect it to the computer is not very good.

 

Using a better device I can now make contact with MIOS again, it says everything is cool and I even tried re-uploading the firmware, but no dice. Still nothing. I can't download any patches I did. I don't see anything but the blocks on the LCD and the LEDs do nothing.

Edited September 11, 2014 by missingsense