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sammichFM Incorrect voltages Rate Topic: -----

#1 User is offline   soup 

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Posted 31 January 2012 - 19:03

Just completed construction and am at the voltage testing phase. Getting 2.2V on the J4 pads and out of both regulator ICs. I've check joints and resoldered sketch ones so I'm thinking I might have fried the 78L05, but it's a consistent 2.2V, so I'm not sure. This is tried with both 9VDC and 8.5VAC PSUs. Much obliged for any suggestions.

My two sammichSID builds went 100% smoothly, had to hit a snag eventually. :V

#2 User is offline   latigid on 

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Posted 31 January 2012 - 19:37

Probably best to wait for Wilba, but can you measure resistance between your 5V rail and ground?

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Posted 31 January 2012 - 20:47

View Postlatigid on, on 31 January 2012 - 19:37, said:

Probably best to wait for Wilba, but can you measure resistance between your 5V rail and ground?


Sure, hadn't detected any shorts with my beeper over the course of the build. It's 3.7kΩ.

#4 User is offline   Imp 

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Posted 31 January 2012 - 21:51

3,7K seems ok. I just measured 3k on my Sammich, with all chips in place.
9V and 8.5Vac seems legit, but to be sure, I'd check if the regulators get enough voltage. It should be at least 7V.

#5 User is offline   soup 

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Posted 31 January 2012 - 22:19

View PostImp, on 31 January 2012 - 21:51, said:

3,7K seems ok. I just measured 3k on my Sammich, with all chips in place.
9V and 8.5Vac seems legit, but to be sure, I'd check if the regulators get enough voltage. It should be at least 7V.


Yeah 7.7V into them both. I don't think this matters, but should JBP (by the rectifier) be shunted? It's marked in the parts list as needing shunts but I don't see them in the jumper configuration guide.

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Posted 12 April 2012 - 21:02

Took some photos, I'm not certain if they'd be any help.

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#7 User is offline   Gilesjuk 

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Posted 12 April 2012 - 21:58

Some of the joints look like the solder hasn't flowed onto the pad properly. Look as them from the side and they'll look round like a toffee apple or something. They should look volcano shaped.

You're using lead-free solder right? (only it looks dull, unlike 60/40 lead solder which is shiny).

This post has been edited by Gilesjuk: 12 April 2012 - 21:59


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