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Old 16th May 2016, 01:15 PM   #1
Jmo is offline Jmo
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Default B1 Issue

I'm having a difficult time getting my newly-built B1 to work. I only connected right in and right out to test. I get power to the board but the only sound I get is buzzing. I've measured all the resistors, the 1M at R200 measures 20k with no power (I don't even have the left input wired). The 10ks at R2 and R3 don't give a steady measurement (the measurements fluctuate without ever landing on one value). I've replaced all three with the same results. Is this normal when they're in-circuit even with no power? My solder connections look okay so I'm at a loss. I've attached pictures of the completed board.
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File Type: jpg B1 top.jpg (425.8 KB, 247 views)
File Type: jpg B1 bottom.jpg (421.6 KB, 241 views)
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Old 16th May 2016, 01:26 PM   #2
AndrewT is offline AndrewT  Scotland
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there's an empty hole at the end of the input trace.

Have you wired the vol pot correctly?

The white wire to the RCA is insulated between the red plastic collars.
The input AND the output require a two wire connection.
The white wire is your second wire and MUST be connected to the source equipment output.
The loop area in the RCA connection of red+white is far too big.
The white wire should be right beside the red wire right till it reaches the solder cup and then run alongside the hot pin till it solders to the RCA body right next to the insulator where the hot comes out.
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Last edited by AndrewT; 16th May 2016 at 01:31 PM.
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Old 17th May 2016, 12:08 AM   #3
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I've just looked at mine and I have the empty holes at the end of the input traces too.

On your photo of the underside of the board, on the side with the blue wires from the pot, follow the straight input trace up from the empty hole to the solder at the other end of the trace. Now go 2 solder joints to the right and zoom in. It doesn't look to be soldered too well to me.
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Old 17th May 2016, 12:36 PM   #4
Jmo is offline Jmo
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Default Thanks for the replies...

I've tried to address the issues raised. At least now I can control the volume of the buzz with the pot, but still not getting an input signal. I guess my soldering skills are worse than I thought.
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Old 17th May 2016, 01:46 PM   #5
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Have you double check the part number of your jfets?
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Old 18th May 2016, 02:32 PM   #6
Jmo is offline Jmo
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Yep, JFETS are correct parts. Thanks.
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Old 18th May 2016, 06:16 PM   #7
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What is the DC voltage across the 1 ohm resistor?

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Old 18th May 2016, 11:50 PM   #8
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Thanks for the reply--the 1 ohm measures 1.2 ohms.
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Old 19th May 2016, 12:11 AM   #9
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I was looking for the DC voltage across the resistor. That way we can know
how much current the circuits are drawing.

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Old 19th May 2016, 12:41 AM   #10
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Right, sorry. DC voltage is 16.8 mV
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