DS question for the day

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CRBMoA
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Post by CRBMoA »

Dipshit question:

Bought a partially popped D&R Comp board. Checked and confirmed values on all the installed bits. Finished it and tried a 3080 I had in my parts bin. The board was built with a socket.

I don't have confidence in the chip (it is a left over from another build, and it never worked in that build) but I don't have another to try on hand.

Are there any common ICs that I could sub in the circuit just to get some noise and confirm the rest of the build?

Thanks!
atreidesheir wrote: Let's build some damned pedals!

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mictester
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Post by mictester »

CRBMoA wrote:Dipshit question:

Bought a partially popped D&R Comp board. Checked and confirmed values on all the installed bits. Finished it and tried a 3080 I had in my parts bin. The board was built with a socket.

I don't have confidence in the chip (it is a left over from another build, and it never worked in that build) but I don't have another to try on hand.

Are there any common ICs that I could sub in the circuit just to get some noise and confirm the rest of the build?

Thanks!
Not really. You could connect up a 741, but leave pin 5 bent out of the socket, which should give you some noise out, but you really need a 3080!
"Why is it humming?" "Because it doesn't know the words!"

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Post by CRBMoA »

Thank You very much! :thumbsup
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Post by CRBMoA »

I have some 3080s on the way, but I am a DIYer, so I can't help but fiddle with it while I wait.

I measured voltages with only the +9v lead running to the board (no ground wire) and got:\

1 = 0.0
2 = 8.78
3 = 8.80
4 = 8.90
5 = 8.46
6 = 8.79
7 = 8.95
8 = 0.0

One and eight will creep up in mV on ocassion, which I attribute to 'Hell if I know?'.

I hooked up the ground wire, repeated the measuring, and got basically identical readings.

I also checked the IC, out of the circuit, with my continuity tester, got no beeps.

Checked the socket on the board. I have continuity on all socket contacts up to the first passive component, and I have no solder bridges or shorts that I can see.

Before I finished populating the board, I checked all of the components against the BOM and the schem. I could check a fourth time, but I believe them to be correct.

Does this mean anything?
atreidesheir wrote: Let's build some damned pedals!

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mictester
Old Solderhand
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Posts: 2915
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 825 times
Contact:

Post by mictester »

CRBMoA wrote:I have some 3080s on the way, but I am a DIYer, so I can't help but fiddle with it while I wait.

I measured voltages with only the +9v lead running to the board (no ground wire) and got:\

1 = 0.0
2 = 8.78
3 = 8.80
4 = 8.90
5 = 8.46
6 = 8.79
7 = 8.95
8 = 0.0

One and eight will creep up in mV on occasion, which I attribute to 'Hell if I know?'.

I hooked up the ground wire, repeated the measuring, and got basically identical readings.

I also checked the IC, out of the circuit, with my continuity tester, got no beeps.

Checked the socket on the board. I have continuity on all socket contacts up to the first passive component, and I have no solder bridges or shorts that I can see.

Before I finished populating the board, I checked all of the components against the BOM and the schem. I could check a fourth time, but I believe them to be correct.

Does this mean anything?
Take the IC out of the socket again, and check the 1/2 rail bias circuit!
"Why is it humming?" "Because it doesn't know the words!"

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