Voltage Variance [resolved]

[rbond]

I just completed my Crack and all resistance checks were spot on.  With the exception of those points that should read zero, the first time I checked voltages they were all out of range.  I checked them again some time later and they were all good.  Third check again reflected bad measurements.  I suspect that my crappy old meter is the problem, but wanted to check the forum to make sure that there is not something about the Crack that could allow voltages to vary significantly over time.  For reference, here are the three checks:


1.   125   81   116
2.   273  173  250
3.      0      0     0
4.   277  173  250
5.   125    78  113 
6.       0      0     0
7.   171   105  152
8.       0      0     0
9.   166   102  150
10.     0       0     0

If you believe that the problem is with the Crack, I'll be happy to post photos of the build.  Many thanks for any help.  Ritchie

[Paul Birkeland]

This could very, very easily be a bad solder joint causing those weird readings.  The most common joint that does exactly this is where the black wires meet at the headphone jack.  If one of them is soldered but the other one is just crimped or passing through and touching but not soldered to the others, then you'll get bad sets of voltages that you're getting.  If you flip the amp over and the wire temporarily makes better contact, you'll get the good set of voltages.

The amp will also sound absolutely terrible with a bad solder joint causing these kinds of issues.

[rbond]

Many thanks for your help - problem resolved!  The specific joints you referred to looked okay, but I reflowed them just in case.  Based on your comment I also studied all the joints and reflowed several.  I subsequently checked the voltages repeatedly and all were consistently fine.  Tried the amplifier for the first time and it sounds great!  Thanks again, Ritchie