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DAC-ASH (dac-end 2 up date)

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phrarod

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Joined 2005
what jumpers did you bridge? 1-2 or 2-3?

That might have some bearing. It looks like 6, 8, 12 on yours are 5v and mine are way off.. I'll swap in the other 74H now and check

OK I just put the other 74H in and I get the same reading as before. Can you please verify your readings on that chip?

Quanghao -- would you please measure yours so we can find out if this could be the possible problem to trace?
 
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phrarod

Member
Joined 2005
ok. Then if you and someone else can verify this maybe its a source of the problem. The schematic doesn't show those pins going to board hook up. I'll look at the datasheet to see what they do.... I wonder where they are suppose to get that voltage?

I think the chances of both my 74H chips being bad is slim
 
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phrarod

Member
Joined 2005
I didn't install the filter network either because I won't be using it. AN bypassed it a long time ago. Have no idea why its in this board.

I just checked the data sheet and 6,8, 12 are the data output so that could be very telling. I'm including the data sheet here.

So my question now is did I blow both of these chips? Or is something wrong on the board? This seems to be the issue if the voltage data out isn't working right.

There is one thing which I can't imagine can cause this issue. When I installed the chip holder I accidentally installed it backwards BUT when I put the chip in its installed in the right orientation. These are just straight pins to the board so I didn't think it would be an issue.

Having touble getting the pdf to upload. Here's the url to it http://www.st.com/stonline/books/pdf/docs/1882.pdf
 
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phrarod

Member
Joined 2005
It appears 2,4,6,8,10,12 are all output and mine is only outputting correctly on 4, 10. So if the chip is getting 5v on the input pin 14 which I am getting then is all the rest internal? Or does it rely on getting those voltages from somewhere else?

I just did a continuity check on that chip holder and doesn't matter it was oriented wrong since I put the chip in the right way all the pins go to the proper places.
 
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quanghao

quanghao

Member
Joined 2009
quanghao.com/
phrarod said:
It appears 2,4,6,8,10,12 are all output and mine is only outputting correctly on 4, 10. So if the chip is getting 5v on the input pin 14 which I am getting then is all the rest internal? Or does it rely on getting those voltages from somewhere else?

I just did a continuity check on that chip holder and doesn't matter it was oriented wrong since I put the chip in the right way all the pins go to the proper places.
Click to expand...

In the image, it is no wrong!
 

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