muldee
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Posts posted by muldee
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Hi guys, my sammichSID is without a working lcd since last year. I tried to fix it in all the possible ways (i'm able to...), but the fact is that I simply can't. So I'm looking for someone that, under payment obviously, wanna give it a try and fix it for me.
Thank you all.
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And finally, sorry to hear you're having such trouble - I think 95% of builds work perfectly, and yours is one of the rare cases where it doesn't... it could be just one bad solder joint or a faulty/broken part, but it's fixable, eventually!
Never mind Wilba, when I joined this "diy electronics" adventure I knew I was (and still I am) a complete noob with zero knowledge about electronics. The funny thing is: I started with a Shruthi (from Mutable Instruments) and everything ended right; so I gave it away as a gift and I bought another one together with the sammichSID (the sacred fire of diy was burning strong in me). The conclusion: at the moment none of the two is working hehe.
I have to improve my studies... ;)
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Regarding backlight, perhaps replacing the BC337 will fix this, and checking the joints for the brightness potentiometer.
Already replaced, still no backlight. I'll check the pot.
Regarding MIDI not working, check you have shunts in JMI and JMO, check the 6N138 is installed correctly... also tell us if you get the "upload request" from the sammichSID (this proves MIDI Out is working).
Already tested and I got the upload request. I have an error message while I try to upload the firmware. By the way I have to read the forum and I have to check a couple of things... I don't want to bother you while I've not tested everything twice, so it's too soon to claim I'm in troubles.
Thanx once again for your fast answers.
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Ok, after a looooong time since my last comment, here I am writing again on my LCD.
Wilba, thanx for the replacing parts, but it was not an LCD backlight failure as I've substitued it with the new one you sent me and, as the previous, it has no backlight too.
So the problem is elsewhere. And my knowledge in electronics isn't too good to understand where. As the lcd is working anyway and I'll use the Sammich only in studio I'm going to leave it as it is.
Now I'm experiencing problems with the midi as I'm not able to load the firmware. By the way I'm reading the forum and I know it is a common issue... I'll perform some tests before posting here.
Thank you for your help
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I performed the backlight test annd this is what I got:
- the led lights up
- the led light is absolutely not affected by backlight trimpot settings
- the voltages are +5V at B+ and +3,13V at B-
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Was the brightness pot set to minimum (fully anti-clockwise)? or did you have it at maximum? It might be relevant to what could have gone wrong.
I started with the pot all the way counterclockwise (as you told me) then, once the backlight was on, I turned it half-way clockwise to have a good backlight intensity.
As soon as I can I'll perform the test on backlight pins. Thanx for your fast answers.
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Ok, I bought a new power supply which is regulated 600 mA 12V tip-positive. I checked the "no load" at 12V on the power supply and it gives me exactly 12V so, as Wilba suggested, it is supposed to be regulated.
I set the JBL shunt on 12V position, then I put a shunt on JR4, no shunts on JPB and the JP shunt in 6581 position. I checked the voltage in orange points and it gave me 10,5V.
Once connected the two boards the LCD came to life as I saw backlight and the "squares" displayed on its upper row, but after 5 minutes the backlight started to blink and in the end it went totally off; I can still see the squares row, so the LCD is working.
As far as I can check I cannot understand where the problem is. Is the LCD backlight definitely dead?
As I have two 6581 and a 12V regulated power supply I have to set both the two shunts in JPB, right?
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As I wrote in I performed the voltages test on my new sammichSID and what I get is everything normal but orange points (12V) whitch are at +15.5V with no shaunts on JPB and at +16.9V with shaunts on JPB.
I'm using this power supply (which I remembered was regulated, but now I'm not so shure...) setted to 12V pin-positive.
I checked the control board too and there is everything ok except for the lcd: if the two boards are stacked toghether and feeded with current, the lcd is supposed to lit even if there's no chips inserted, am I right? I mean, the lcd should show "black squares" in the the upper row (I suppose).In my case it is totally off.
Thank you for your support. I'm new in the forum and in electronics so please be patient with my mistakes and low preparation.
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Hi guys, I have a similar problem with my sammich. All the orange points (12V) are at +15.5V with no shaunts on JPB and at +16.9V with shaunts on JPB. All the other points are right.
My 7805 and 7809 are mounted correctly. Someone has any idea?
Repair wanted
in MIDIbox SID
Posted
Never mind and thank you very much for your answer. Mumbling on it brought me to re-verify everything I did yesterday night, and I found out I missed a step burning mi new PIC. Now everything works. I did it on my own, so thread can be closed.