I fired (no pun
up the SE I'm building for my wife, with no tubes in it, to check voltages and after about 20 seconds I had smoke from it. It's the Edcor XPWR131-120. I've done a visual check and measured and the only thing off is C6 measuring about 10Uf, in circuit, instead of 47Uf. My soldering station packed in in and I won't be getting another for a few days, or I'd pull the transformer wires from the board, to try and isolate the problem. Oh and it didn't even blow the 3 amp fuse. Any help much appreciated.
up the SE I'm building for my wife, with no tubes in it, to check voltages and after about 20 seconds I had smoke from it. It's the Edcor XPWR131-120. I've done a visual check and measured and the only thing off is C6 measuring about 10Uf, in circuit, instead of 47Uf. My soldering station packed in in and I won't be getting another for a few days, or I'd pull the transformer wires from the board, to try and isolate the problem. Oh and it didn't even blow the 3 amp fuse. Any help much appreciated.Well, I pulled all the secondary leads from the board and taped off the wires....Smoke coming out of transformer still....So I'm guessing the transformer (brand new) is faulty. I removed the wire pair by pair and never once blew the fuse. So if it's not a faulty transformer, what on the board would cause this? I have a Cl-80 thermistor from back of fuse to a leg on the on/off switch. Also a CL-140 on the center tap of the 330V. I mounted this to one of those green screw blocks at T1-1, cutting one of the legs off and glue gunning that side to the board. I did notice that I hadn't cut the leg off short enough and it pierced the board into the ground trace. This shouldn't have caused a problem though, I would think, just bypassing the thermistor. I took it apart and fixed by cutting the leg shorter and filling the cavity with hot glue. So I'm wondering if I caused this or if the transformer is wonky?
You should not power the amp without a load on the PS.
Powereing the PT alone is OK but if you connect it to caps without a load the voltages can surge a lot higher due to regulation %.
Always power from a BULB in series with a VARIAC, AND a LOAD on the PS side, some calculated big resistor to protect parts like capacitors....
After you are secure with your amp, remove the bulb and power with only the variac, then 3d test is variac full load on.
Transformers are tested before the leave factory for insulation, it is very rare to have this happen.
Powereing the PT alone is OK but if you connect it to caps without a load the voltages can surge a lot higher due to regulation %.
Always power from a BULB in series with a VARIAC, AND a LOAD on the PS side, some calculated big resistor to protect parts like capacitors....
After you are secure with your amp, remove the bulb and power with only the variac, then 3d test is variac full load on.
Transformers are tested before the leave factory for insulation, it is very rare to have this happen.
Yeah, I wondered about getting a dud. Didn't seem likely. I also wondered about testing without a load. I was following the assembly instructions, unless I misunderstood something? I have a dim bulb tester and a variac and I'll use them next time. I followed the same instructions when I built the TLSE 45 amp and to problems. Thanks for setting me straight.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.