How is your grounding on that channel? Make sure it is secure & a good connection to the PSU ground.

Peter

Hi,

I am new to this board. I got a JFET kit from scott and it is my first project working with AC, I am a bit nervous about working with AC but anyway I am working on the PSU board and having a problem:

I did the test as said in the manual to test the 25.5VDC, with a 10k resistor as a load. And there is no voltage. Then I measure the AC across the input of the B30, I found that the AC voltage is very low.. around 3-4VAC. I don't know if I measure it in a correct way because I didn't unsolder the transformer wire when I measure the AC across it, they are still attached to the pcb (I clip the DVM probe to the wire from the bottom of the pcb). What should I do next?

Also I am wiring with 220VAC. As said in the point-point diagram, I should just connect the red and black input wire of the transformer to the center lugs of the switch, and leave the yellow and purple "NC", is "NC" = Not Connected?
so should I just leave the yellow and purple untouch, OR connect the yellow and purple wire to each other? (right now I leave them untouch).

Thanks!

laiben

ok. Scott replied me on this: the yellow and purple should connect together.
Now problem solved. the PSU board is done. I am making the audio board.

laiben

Hi, I am also a newcomer to this board. I just finished my HJFP2 kit (rev. C), and I encountered a hum issue similar to the one described by Steve Crockett on the previous page. Here's what happens:

If there is no microphone plugged in, it hums quite loudly as you turn up the gain. When a dynamic mic is plugged in, the hum is significantly reduced, but still there. Both channels sound fine except for the hum.

When a condenser mic is plugged in, and the +48v switch is engaged, the hum disappears completely, and everything sounds just the way it should; dead quiet with lots of gain. When phantom power is switched off, the hum returns, increasing as the phantom power ramps down. If the phantom power switch is engaged with a dynamic mic plugged in, there is no effect on the hum.

When an instrument is plugged into the DI jack, there is no hum, and it sounds fine. Both channels exhibit the same behavior.

I discovered that I can minimize, but not completely eliminate the hum by rotating the power transformer, but it requires a slightly different orientation for each channel. I can get one channel acceptably quiet, but not both. I have tried moving the twisted wires around, changing the orientation of the DI jack, and disconnecting the pilot light, but none of that made any difference. Apparently, I did something wrong in the assembly, but I don't know where to go from here to troubleshoot. All the voltage checks as outlined in the instructions are exactly what they should be, and I don't see any obvious problems with the solder joints on the PSU board.

It's still completely usable with phantom powered mics and DI, so it's not a total loss. Did anyone else encounter anything like this, and if so how did you fix it?

I am waiting for a reply from Scott, so if he or his tech gets back to me with a solution, I will post it here.

Thanks,
Jerry

Hi,

I'm experiencing the same symptoms as the last poster -- although I haven't tried a dynamic mic, yet.

Any solutions to this?

Thanks,

- Jim

DYNOMIKE -

"Secondly, neither channel's xlr inputs work"

I had the same problem and it was because I had wired the DI brown wire to the "G" pad instead of the "T/S" pad. The DI signal worked fine, but I couldn't get the mic input to come up with anything. Then I discovered that I misread teh instructions when it says,

"There is a spare "G" hole nex t to the 'T/S' pad that is unused."

I red it the other way around at 6am as I was struggling to stay awake and continue working. Maybe that helps you along.

Justin

Could someone tell me how long does it really take for a HJFP2 kit to arrive when using paypal? I send a couple of emails to Scott Hampton about my HJFP2 kit,but he have'nt reply for a week and a half.

finally had a chance to sit down and measure some voltages(8months later). Remembering again that I'm a total newbie and I built this thing with paint by number. Here's what I got

v1=0.1
v2=13.6
v3=.94
v4=1.27
v5=24.1
v6=25.6
v7=12.9
v8=2
v9=1.9

this is what it's supposed to read

v1=0
v2=13.6
v3=1.07
v4=1.02
v5=23.12
v6=25.56
v7=11.98
v8=0.00
v9=4.83

again my preamp was fine for a few months and then the right side just died. se my previous post.

what does this mean, which part is bad. total newbie. thanks again.