DIY Mic Pre Kits, Lunchbox Mic Preamp Kits, Power Supply Kits

Hi

I received the stereo package (psu1848 +trafo + 2x sc1) package today.
(Very well packed and organized, thanks!)
So I started building the psu
(I'm referring to PSU-1848AssemblyGuide.pdf)

After applying 230V 50Hz (Netherlands, Europe)
The leds light up, ok
I adjust R3 (5k) to get to 48V (R3 = 4.4k), ok
I start adjusting R6 (2k) to get to +18V, but
it reads and stays at around 25V and....
R4 (120) starts smoking and turning black

So I have removed R4 (still reading 119.6 Ohm)

troubleshooting:

the trim-resistors still function, checked
the resistor are stil ok, checked
the diodes still function, checked

I have soldered (another) R4 back in place

power up; testing again:

both leds light up, ok
ac1 - ct - ac2 all 20V ac, checked
48V to ground, ok ,checked
+ to ground reads 25V, adjusting the trim-resistor(R6) doesn't seem to affect it, turning it down to minimum makes the R4 resistor starting to smoke again...
- to ground reads 25V, adjusting the trim-resistor(R7) doesn't seem to affect this as well..... I didn't dare to adjust R7 further down.

So, I guess it's time for me to go to bed
Anyone any ideas on how to continue after a good night sleep?

Thanks & Cheers

I've got it

I switched LM337.....

Ack! Hope it's still working.

Don't worry about it, everybody makes mistakes... I made an even worse mistake while designing the 1st PSU-1848 prototype. I switched to use the LM317 regulator but used the footprint of the 7818 (in which the pins are different). The board, regulator and transformer was getting hot until I finally realized my mistake.

I had to throw away a whole batch of prototype PCBs.

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