Yes, running a 4 ohm load on an amp rated only to 8 ohms is overloading the amp.   If you keep having to reset the circuit breaker, that should be a clue the amp is not happy.  And you should stop doing that before the amp is damaged, if it is not already damaged.

It is LEAST likely to be a transformer, and there is no "worse" after a transformer on the failure list.

You may have worn out the breaker, but it isn't the breaker's fault.  YTou need to stop overloading the amp, then we need to determine if the amp has suffered some damage causing it not to power up.

Oh come on, The TIP41C will better handle the 100v transients than the TIP41.   Improves the stereo soundstaging.

A store might have a good return policy, but that only helps you at the outset.   Chances are six months later, no one will take it as a return.  SO you might also consider support.  Peavey has repair stations everywhere - I am one of them.  So does Fender - I am one of those too.  SO warranty or after warranty, you can get them serviced.  Now, go look up where the nearest authorized repair stations are for Acoustic and Behringer.    They may tell you to box it up and ship it to them, but unless you kept the box, ever try to find one to fit a 2x12 combo amp?  Not to mention the $30-50 shipping cost.   Or you may luck out and be near one of their few places.

Call Peavey or Fender and ask for a schematic so your local tech can work on an amp.  They'll send it to you in minutes. Now call Behringer and ask for a schematic.   No dice.   Peavey will sell any part to anyone who calls.  Most other companies won't, they refer you to their dealers.

Age of an amp is not nearly as important as condition.   There are PLENTY of guys gigging regularly with 30 year old amps.  There are 2-3 year old amps that are beat into junk.   As a tech I don;t care what year an amp was made, I leave that for the amp fans to obsess over.  I do care what revision version an amp is of course, because the circuits change.

It makes a difference what you want to play.  A pedal steel cat wants a different amp from the Metallica tribute band.

Try as many amps as you can.  I like Peavey as a company, and recommend their amps a lot.  The Bandit is one of the worlds most popular amps for a reason.  SOunds good, works well, is well supported.  Might not be a 2x12 or 100 watts, but worth a look.

Now just my own opinion on the DSP stuff.  Ever get one of those multi-effect pedals like DOD makes?  Got a hundred patches, and every effect you can imagine.  And at first it is exciting to run through all the patches.  But after a short while, you wind up using three of them and rarely any others.  SOme of the entry level DSP amps do this as well, in my mind.  And modelling itself is a compromise.   You get a switch to select Fender Twin, Marshall Plexi, AMpeg something,or whatever.   And sure enough, the amp sounds kinda like a Twin and kinda like the Marshall and kinda like whatever it says it is.  But no one would confuse the sound and dynamics with the real original.  Like the Metallica or Beatles tribute bands don;t really sound just like Metallica and the Beatles.

On the other hand, the drunks dancing in front of you in the club gig don;t care.  SO if your multi-modeller sounds close enough to whatever cover tune you are playing, that's good enough.  I guess my point is not to be overly impressed at all the modelling and DSP, consider those in terms of the gig it will be used in.

Entry level amps are just that.  Aimed at players early in their career.  The stuff tends to be not as robust as the more pro stuff.  tends to be feature laden, with extra eye and ear candy.

Hi, good form would be to link us to the schematic you are using.

The center tap is at 700v, which means the power tube plates are at 700v.  The 350v is on the screens.

The power tubes are cathode driven, so any current through the transistors is also coming through the tube.

One can grasp each filter cap amd wiggle it.  If the hum comes and goes when you do that, you have a loose connection of some sort.  A loose connection is usually cracked solder, which we simply resolder.  But the wire lead from the cap might be broken, or the copper lines on the pc board might be cracked.

An even simpler test would be to ball up your fist and whack the top of the amp - no disassembly required.  If that stops or starts the hum or indeed if the amp reacts at all, that tells us some connection is loose inside.  Turn the reverb down when you whack.

One might also just bite the bullet and flip the board over and resolder them regardless of how they appear, fresh solder can;t hurt, and while under there, look close at or resolder the controls and jacks.

While the amp is running, use something insulated, like a wooden chopstick, to push on each part on the board, looking for any that react.

with just one half of the brown winding working, you still ought to get your 30vDC rails.   You could lift D108-111 to remove the fan influence and see if your voltage comes back down.


AHA!   I just looked more closely at the schematic, and finally realized what I was seeing.   There is a reason the fan circuit does not reference ground.  I was trying to figure how the same set of 23v wires could make +/-30vDC or 60v, and still make only 40v in the fan supply.

But it just sank in that the fan supply runs off one of the low voltage wires and one of the high voltage wires.  In other words the fan is running off what amounts to a 34-0-23 "winding".   Since it has no ground reference, the lopsidedness matters not.

But if one of the diodes in the fan supply shorts, or the C116 or C117, or not swure what else, it would wind up shorting the red wire to the brown wire, and that might be the reason the brown wire haqs burnt open inside the tranny.

So:
1.  Lift the four fan supply diodes.  Check them while there for shorts.  See if the remaining low voltage wire now allows the +/-30vDC down there that would allow the Vregs to come home.

2.  Open up the transformer to see if you got lucky and it might be repairable.

3.  Solve the fan supply.  Look for anything in it that might be shorted.

Yes, one open side of that center tapped brown winding OUGHT to still provide correct DC voltages.   I have not yet put any mental energy into it, but it may be possible with that open, the floating fan supply off the same leads is creating an ersatz voltage doubler somehow.

And there it is.

The open winding leaving D with no continuity to the rest and zero volts output.  Just how that resulted in the one pin having twice voltage I'll have to think about.   But the transformer is bad.


Now sincve the transformer has to come out anyway to replace, you might as well try to fix it.   It is POSSIBLE the problem is in the lead wires and not th windings.  The transformer inside is wound with enamel coated wire, not the colored is=nsulated wires you see coming out.  Inside will be some point where the lead wire is soldered to the winding wire.   There may be solder terminals you can see from the outside, or they may be buried.  We need to go inside enough to see where th brown wire connects to determine if the connection to it has broken, or if the end of the winding wire snapped off right at that point.

And we cannot yet rule out the crimped-on female push connetor on the wire end.  Check that joint.

If you have to, you may need to slice open the fish paper (heavy cardboard) around the transformer middle.

Hey, what is there to lose?