VRDN: bipolar regulator PCB for line level ckts: ±11V to ±20V @ 1.5A with "De-Noiser"

[volpar]

So the only difference that i can find is the operating temperature range. The TG 317 & 337 are 0 to +125C and the BTG are -40 to +125C. Totally guessing but Sound like same chip design to work in a harsher climate, perhaps aviation.

 

[aljordan]

BTG must mean better temperature grade

 

[volpar]

in the mean time how dose the masses like this toroidal for the VRDN https://www.newark.com/triad-magnetics/vpt36-690/toroidal-power-transformer/dp/11R8072

 

[Monk55]

I like the static shield between primary and secondary.

 

[rikiheck]

Yes, my investigations suggest the differences in the various LM317s are minimal. The suffixes indicate things like the type of package. See
https://www.onsemi.com/products/power-management/linear-regulators-ldo/lm317
for the comparison between the different models. They all have suffixes. The LM317TG seems to be the basic one in the TO220 package. The B adds something, but I can't see what (other than a few cents).

 

[rikiheck]

Oh, the TG has slightly greater voltage drop than the BTG (2.9V vs 2.8V).

 

[volpar]

I see that as well now super minimal. So maybe the real question is for the "parts list", Mark can you say was the selection of LM337TG just chance over the LM337BTG. And same with the LM317BTG was added to the parts list by chance over the LM317TG. Or were they selected for a reason.

 

[volpar]

OK getting closer. I think power one of these up today. Yes, I’m still missing LM 317 and 337 on the one board. I’m expecting them tomorrow.

 

[volpar]

First of four dialed in to 18-18.

 

[volpar]

A bit of help please on one of my VRDN regulators, the negative voltage rail is not adjustable. It’s giving me -23 VDC. Do you think the trim pot has shorted out? or the LM337 is faulty in someway. This beyond the scope of my paint by colors and not sure even how to check either one or test them. I have the parts to throw at it and see if it fixes it. But would rather learn something! If someone has the patience for that task. 😄

 

[Monk55]

Compare circuit voltages from the working board to the faulty board

 

[volpar]

Yes, the first one both left and right sides positive or negative fully adjustable to +18-18 Vdc.

The second one just the positive side is adjustable to +18 V and the negative side is nonadjustable at all. Just sits at -23 Vdc. And no heat or magic white smoke 💨

 

[volpar]

Well I can’t find the problem. I changed the rectifier and the trim pot and resoldered about eight connections.

 

[volpar]

😤

 

[volpar]

OK I decided to go ahead and to replace the LM337. Well that was hard to get out. Put the new one in still have the same problem. This is well above my pay grade. Any ideas?

 

[richb]

Compare circuit voltages from the working board to the faulty board

This is the usual way forward - to expand: print out the schematic, probe every voltage of the non-working board and annotate on the schematic, post here! Then we have something concrete to work from

 

[volpar]

ok will start on that soon. just get voltage reading at each component?

 

[bhjazz]

OK I decided to go ahead and to replace the LM337. Well that was hard to get out. Put the new one in still have the same problem. This is well above my pay grade. Any ideas?

Did you build it with a different LM337 than specified but use the normal parts from the Rev.A BOM? If so, you'll want to read Mark's info in post #198. It refers to TI parts but can apply to other versions of the 33x chips, if I am not mistaken.
https://www.diyaudio.com/community/...o-20v-1-5a-with-de-noiser.355883/post-6451732

Additionally, you'll want to see Mark's other info on post #694 (which links to other posts):
https://www.diyaudio.com/community/...o-20v-1-5a-with-de-noiser.355883/post-7322633

 

[mchambin]

The second one just the positive side is adjustable to +18 V and the negative side is nonadjustable at all. Just sits at -23 Vdc. And no heat or magic white smoke 💨

Just sits at -23V.
Because it is working as if the trim pot was set at maximum, I think the trouble is there.
At the trim pot PCB tracks, a short or an open circuit.

 

[bhjazz]

volpar, could you post a pic of the backside of your problem board?