fired it up and smoke comes out of PT

[Roe]

instead of using a lighting bulp I'm using an extra small fuse.

[selloutrr]

fuses get expensive.

Some of the variac's allow you to view the amps drawn as you apply voltage. If you have a problem you can power down early without having to replace fuses It's really a great tool to have. It gives you confidence the build is correct. You lower stress on components during first time power ups. You can properly form capacitors, as well as giving you the ability to lower or increase voltage for test measurements.

[John_P_WI]

Plus variacs vibrates if there is a short. You can feel something is wrong even without looking at a meter as you dial up the voltage...

[FUCHSAUDIO]

What are you trying to do with this winding ?

believe it or not, it started because i had a 269ex transformer sitting around. i looked for a project to use it and ended up finding the matchless vibrobox/hotbox combo. then i decided to just do the vibrobox.

so after getting the parts to finish it up. i ended up frying the part that started it all.

here is the schematic of what i am trying to do (the correct schematic)

http://www.prowessamplifiers.com/schema ... robox.html

The Hammond diagrams (unless I looked at the wrong one) all showed taps on the 6.3 V secondaries. If not, then the bridge wiring hurt it.

[FUCHSAUDIO]

Based on your schematic, I would say the dc heater circuit is marginally useful. I would build a simple voltage doubler on that winding (use a couple of 6800 UF caps and strong diodes low voltage/high current), and regulate to 6 volts with a 7806 packaged regulator. That would be quiet and worth doing... imho.

[wsaraceni]

thanks andy. ill research that some more. im sure, based on your designs, you'd know a thing or two about DC heater supplies. I'll just have to research a little more. im at the stage where i can build what it says on the paper (marginally well) but need a little more info when it comes to any deviation.

[Bob-I]

instead of using a lighting bulp I'm using an extra small fuse.

That doesn't do the same thing. The light bulb will limit the voltage if there's a problem that causes excessive current, the fuse will just blow, possibly even if everything is normal.

[Roe]

instead of using a lighting bulp I'm using an extra small fuse.

That doesn't do the same thing. The light bulb will limit the voltage if there's a problem that causes excessive current, the fuse will just blow, possibly even if everything is normal.

yes buts easier to just pop in a fuse.

[wsaraceni]

so i got the new PT In the mail and decided to try to just hook it up with the AC heaters direct to the tubes. at least until i can learn more about DC heaters. So nothing popped this time, all my voltages look good, but all i get is a nice loud hum. no sound coming through. i should just buy everything. im not doing too well on these DIY projects.

[Alexo]

I'll take a hum over a cloud of smoke any day - that is progress!

[mcrracer]

so i got the new PT In the mail and decided to try to just hook it up with the AC heaters direct to the tubes. at least until i can learn more about DC heaters. So nothing popped this time, all my voltages look good, but all i get is a nice loud hum. no sound coming through. i should just buy everything. im not doing too well on these DIY projects.

I take it that you still did not hook up a light bulb limiter first. DIY is easy enough IF you follow some basics. Doing it YOUR way is a formula for disaster.
FIRST learn about the hobby you want to pursue. You would not try brain surgery until you learned a little about anatomy and medicine. Same thing applies here. Do some reading and studying to at least know which way is up. Learn how to read a schematic so you will know if the one you want to use is drawn correctly or not. When several people gives you the same advice it is most likely sound. Follow it!. Building your own tube amps can be very fulfilling. It is a great feeling to build it, plug it in and hear the guitar sounds you were expecting. But there are quite a few steps between wanting to do it and actually completing an amp. Don' try to take short cuts...you see where your short cuts got you.
Maybe try a simple SE amp first to get the feeling of what goes where and what does what. This is not hard but you do need to know something about it and how to properly use the tools required. Also you need to know the safety procedures. Do some reading then try it again. I have been doing this since the late 60s and I still make mistakes from time to time. I did not learn to do this over night. Take your time and have some fun.

[wsaraceni]

i did hook up a light bulb meter this time. had zero issues. i followed the steps on this page.

http://tubenewbie.com/light_bulb_current_limiter.html

i just have to get a dual gang box to make a permanent enclosure for it now. and i'll just mount it on the wall and use it every time i do a power up now.

and im not trying to take shortcuts. this started out as a single ended amp (ax84 p1). i built it, modded it, and then gutted it because i never used it.

then i tried (unsuccessfully) to do a trainwreck express. the express i've since tried to clean up some and have made progress on it.

also in that time i bought a blown up fender blues jr i turned into an 18 watt lite iib. i love that, and plan on adding vvr and a new OT in the future. all of which i have the parts to, just havent gotten around to it.

so while i know 0 about DC heater supplies, and it cost me $50 to learn a little about them, im not just taking shortcuts and trying to do this without learning.

[FUCHSAUDIO]

I would check : If you don't have hum balance resistors, you'll have lots of hum. Make sure your power supply filter caps and diodes are wired correctly.
Basic voltage tests are wise. Maybe remove preamp tubes, and try to bias your power tubes with no preamp tubes first. Take it a stage at a time. Add the PI, then preamp tubes one by one, to hopefully get sound, and no hum etc....

[wsaraceni]

andy, there is no powersection. its just a tube tremolo pedal that matchless used to make. looks like a single gain stage, into a tone stack, into another gain stage with a trem connected to it. i should also say, that there is hum, but no guitar tone is passing thought at all. so its not like its hum on top of what i should be seeing, it's just hum. im going thought piece by piece checking it all out again. i am seeing about 260v on the B+ and 6.27v AC on the heaters

[FUCHSAUDIO]

Sorry Bill, I was in "default diagnostic mode"...lol. Have fun.