Babelfish XJ , or JX …….. or whatever (Aleph X servo for Greedy Boyz)

Hi Zen Mod,

Little question for you... I've assembled most of the IPS boards (they're both finished at the same level of parts). I always measure all parts before soldering and after (i know in circuit does not always work due to other parts in the circuit but testing two PCBs I can at least compare them).

I was waiting on my 250K resistor to arrive (wanted to change the ones I had in place). Once soldered in place and measured in circuit using my LCR, I realized that R8 and R46 are far apart (~25K vs ~44K), then I decided to measure the other PCB and both sides measures the same ~25K... So... I'm trying to identify why on only one of the two PCBs I have this issue... I decided to measure all resistors in circuit to compare them and all value read very closely except R7 and R50 in circuit should measure the same (~18K) but on the PCB that has the issue, same side as R8, R7 measure ~40k instead of the ~18K...

I only have Q1, Q8, Q13, Q14 and Q15 soldered for transistors.

Do you have any pointers for me? I already did desolder R8 to measure it and the value is good. I will do the same for R7

Thanks
Do
 
Took R7 out and it is the proper 100k value... Only thing I could see wrong is a bad transistor. Caps are rarely defective when new and I measured them prior soldering them. Don't have the 7v5 zeners in yet. Aside R7 and R8 which don't measure proper in circuit on one PCB, measuring them out of circuit I read the proper values. I don't think I should continue to populate the PCBs prior to finding the issue, right?
 
After several hours of checking everything with magnifying glass, checking with LCR meter and multimeter, removing components, I finally found and fix the issue! There was a bad PCB vias... The solder joint underneath has no trace just the vias but the solder didn't reach the other side completely. The top of the vias must have been cracked/broken and not making proper connexion with the trace. Anyways, as I was re-flowing the top surface of this joint, I tested and voilà! Everything seem to measure like the other PCB.

I must be one of the very unlucky people I guess... LOL! This is something that usually never happens and it had to be me! :cuss: :D :D

Anyways, problem aside, I can now move along!

I'd like to thank Zen Mod, he's amazingly patient man and always helping! And I would like to apologize for all the trouble of my million questions.

Thanks
Do
 
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Official Court Jester
Joined 2003
Paid Member
I'm not familiar with exact SP , but certainly you need to use one intended for bridged amps , so no really connection with GND

got your emails, working on catching up with correspondence

even if I'm Mighty ZM , and there are at least dozen of us in this Gorgeous Body , Greedy Boyz are plenty and we are alone

:clown: