So Close...Yet So Far [resolved]

[Paul Birkeland]

Paul,

5/6 on the A channel is 0.632V, but on the B channel I am getting that same 535V on the 5/6 [and it is 535V versus 0.535V]

On terminal 9 it is 3.746V.  and on terminal 19 it is 2.964V

When you see something like 535V in a kit with a lot less voltage than that present, that tends to indicate a bad solder joint on a ground wire in the amp. 

Terminals 9 and 19 show about 3V of AC signal, and this is the output of the preamp.  Can you turn the volume up all the way on the preamp and run this signal through it again, then report the AC voltages available at 9, 19, and the left and right output jacks?

 

[anthonynchandler]

Good afternoon Paul,

I went over all of the black wire and ground lug solder points with a resolder, to no avail.

With the signal at full and the preamp volume at full I get

Terminal 9  reads. 3.482V
Terminal 19 reads 2.958V

On the output lugs (All 4) I get a 0.0V

I should also mention that if I hook my signal up to the Moreplay and then feed that to my Crack, I can hear the signal in the Crack (both when the Moreplay is on or off; the balance and volume will affect the signal going to the Crack).  It will not send a signal to my amps though.  Sooo I am assuming the signal is just passing through the Moreplay without being amplified? I had a similar moment when I ran the signal through one output jack and out of the other only to realize it was just a U loop  through one to the other! Bah ha ha.

Sorry...I know this seems strange.

Thanks,
Anthony

When you see something like 535V in a kit with a lot less voltage than that present, that tends to indicate a bad solder joint on a ground wire in the amp. 

Terminals 9 and 19 show about 3V of AC signal, and this is the output of the preamp.  Can you turn the volume up all the way on the preamp and run this signal through it again, then report the AC voltages available at 9, 19, and the left and right output jacks?

 

[Paul Birkeland]

Can I see what the wiring looks like at the volume pot?

I would suspect that the CAT5 leaving the volume pot may have gotten overheated and melted together, which will short out the signal trying to get out of the preamp.

Your preamp is accepting line level signals and amplifying it properly, but it's not getting from the coupling caps to the output jacks. 

 

[anthonynchandler]

Interesting. Okay, I will send a few images at different angles. If the cat 5 is melted, then is it at the pot or midstream?  Would you suggest stripping those and reatttaching?  I guess what surprises me then would be that both channels are shorting, but then maybe a short anywhere does the same thing to the whole system - ha ha ha.

Thanks,
Anthony

 

[Paul Birkeland]

If you put the volume pot about in the middle, what are the DC resistances from ground to all of the lugs?

 

[Doc B]

That upper center terminal on the pot is really crusty with flux and needs to be reheated.

 

[anthonynchandler]

I will redo the volume pot now, specifically the one you suggested.

Resistence measurements before resolder with black on terminal 23, volume at mid and power on Moreplay [but they measure the same resitence with power off)

Left Top (white wire)  9.76
Middle Top                  0.945
Right Top                      0.2

Left Bottom                  9.95
Middle Bottom            0.881
Right Bottom                0.2

 

[Paul Birkeland]

Now with the pot turned most of the way up, play your 60Hz tone into the amp and check for signal on the middle lug of the volume pot on each level.

 

[anthonynchandler]

Paul,

Not sure what to use to measure signal, but if it is resistance then on middle lug it is

Top 0.915
Bottom 0.853

If it is AC voltage, then it is
Top.  149V
Bottom 307.8V

I retouched solder on all of the lugs on the volume before this measurement

 

[dth31]

I never knew how easy it was to make your own signal generator. Can’t tell you how many times I wished I had one. Now I feel embarrassed for not knowing how simple and easy it is. Thank you for the simple, clear description of how to do so!

Dave

 

[anthonynchandler]

EUREKA!

WE HAVE SOUND!  I believe that it must have been the "crusty" solder on the volume pot which Paul spotted.  I would like to give thanks to Paul for all of the support with learning to follow the signal and taking time to get back to me when things did not make sense due to my lack of technical expertise.

I think that it will take some time to run the circuit and figure out how make it sound best within my system. The Moreplay does not sound like I would expect, so my ears will also need to adjust and figure out volumes and balance for my room. Regardless, I will write something and post it in a week or so.

Thanks again. It was not an easy process when it seemed easier than my Crack build, but then seemed to stall just before the finish line.

Be well.
Anthony Chandler