JLH 2005

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#22
Hi ferret. I had the PCBs made by Olimex, who are still around but not doing custom PCBs any more. Likely they can't compete with the Chinese board shops. The clearances are such that doing it yourself is a possibility, although the boards are fairly big (100x160) and it might be hard to get consistent etching results across such a wide area. Probably not a good choice for your first try.
I had good results fairly recently using PCBWay, with boards using SMD components so much tighter clearance.
 
#27
Mamak said:
Hi all.
I build jlh 2005 using Paulb circuit and pcb. Now i face issue sound is too low. Use +-30v supply range. And use 2sc5200 for power output. 2 pcs 2sc5200 already died cause over bias(sad)
I double check hfe value for bc560, bd139 and bd 140 all in good range.

I don't have oscilloscopes and signal generator to measure input output gain.
Click to expand...

Oscillations maybe (in addition to undersized heatsink)???

Can we see the PCB tracks side of the PCB you used?

That Geoff Moss PCB looks good.

Ensure that the signal ground returns and the power supply rails' decoupling returns are routed back to common via separate routes:

1652932971115.png


Also, the VAS in JLH-2005 is not HF compensated (... unless I'm missing something obvious); I'd expect to see something there. Like Miller or shuntlag... output stage inclusive Miller... 2-pole compensation. But it seems there's nothing.

Where is that NFB signal point of origin (pick-up point) located on your PCB?
 
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