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SammichSID LCD problem *FIXED*


dorremifasol
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Greetings,

I'm finishing the building of my sammichSID and it seems to work, as I can send the program to it through MIOS Studio, but the LCD has no shown signs of, life ever. I have checked all the voltages, but I can't find anything bad about them. The solder points seems to be ok too.

In the building guide, page 18 shows that I should have had a row of black rectangles, but I never saw them, though I have changed the brightness and contrasts in all ways.

Are there any specific points I should look into in order to trace the problem?

Thank you,

Alberto

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The LCD was tested before I packed it, so it should work.

Do you see the LCD backlight when it's connected?

Was the contrast pot fully counterclockwise?

Most likely you have one pin that isn't soldered properly. Probably the ground pin, 5V pin or the contrast pin.

Test there are no shorts between adjacent pins on the LCD header.

Test there is continuity between pins on the LCD and matching pins on the bottom of the PCB. You will need to assemble the PCBs without a case.

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Thank you Wilba,

I resoldered all the pins again, and I also set the contrast fully counterclockwise. It seems that the text it's only visible in that position.

Now everything works, my sammichSID is alive! It has a better S/N ratio than I expected, very good work!

Just one last question. The input is stereo as well? Will each channel go to a different SID for filtering?

Cheers,

One happy sammichSID customer.

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Well, now that's unexpected. I just wrote the previous message and mounted the sammichSID in the case. Turned it on and... it doesn't turn on.

Now it's unmounted again, and I can't get power from GND +5v or +9v. :(

What could have gone wrong from only mounting it?

EDIT: found it. I guess I have to improve my soldering abilities :/

Edited by dorremifasol
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Maybe you had a bad solder joint for the power socket or switch, and mounting the rear panel moved it. Or you didn't cut the leads on the bottom short enough, causing the bottom panel to push them into touching, or something like that.

Take the base PCB out of the case and take out the ICs including SIDs.

Check the bottom of the PCB for any shorts or leads that are too long and now touching.

Then with power connected and switch turned on, check what the voltage is at J1 and on the 7809 between the pins marked with orange and green dots. It should be around 12V or the same as your input DC voltage.

You need to actually do some tests and prove what is connected that should be connected, and what might be shorting with something else. Check that none of your power rails (i.e. 12V, 9V, 5V, Gnd) are shorting with each other.

Report every test you did. I can't help if you just ask vague questions like "why isn't it working?".

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Just one last question. The input is stereo as well? Will each channel go to a different SID for filtering?

yes, and you can apply different filter settings/modulations to the left/right filter by selecting the L/R channel via SHIFT->GP button 1 and changing the parameters in FIL and MOD page.

Best Regards, Thorsten.

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