Amp died...

[HTH AMPS]

My guess is that the first valve stage is common to both channels and runs of a separate LT supply (this is some that you can use a DC supply in the first few valve stages and thus reduce hum).

sounds plausable, (like JPF said) if the preamp valves are getting voltage to the heaters but the output stage isn't, it could be that the output stage has AC heaters while the preamp from the PI onwards has DC heaters.

defo a job for a tech imo.

[silentrage]

Thanks! I was told by some bugera owners to just buy new tubes, but I dropped it off for repairs anyway just to make sure.
I'll call them on monday to find out what was the culprit. :)

[HTH AMPS]

just trying to find a schematic for this thing - interestingly enough it appears to be a 5150+ clone.

[silentrage]

Yeah that's supposed to be exactly what it is.
I don't have the details anymore but I saw a post about how a guy who worked for peavey went to Bugera and started building these amps for them.

It may have a better clean section than the 5150+, although I'm not sure because I never had a 5150+.

[silentrage]

Amp's back after 2 business days from dropping it off, so I'll give them pluses for that.

The technician said the problem was a loose clip that caused a short, he didn't say if it caused a transformer to fail or an internal fuse to blow, but either way it was those damn clips that they used as a cheaper alternative to direct soldering on the pcb.

I'm gonna open it up and inspect it again before turning it on just to make sure.

Thanks for all the pointers and support on this one guys!

The moral of the story: if you buy a bugera amp, go in and finish the assembly before you use it. :/

[jpfamps]

OK, sounds like the LT uses Molex (or even worse IDC!) connectors to run the LT between boards.  This type of connection makes assembly quicker and often makes servicing easier, however they are prone to coming loose.

Both the LT and the HT present different problems for connectors — the LT conducts relatively high currents so needs to be low impedance, whereas the HT obviously has high voltages on it. I've seen problems with both.

[silentrage]

They look exactly like the power connectors in my PC, which I think are molex ones right?

Yeah I should've opened it up and checked it out first, might've saved myself some trouble.
It looks like the tech just super glued the problem connectors for the "fix", I knew it was too much to hope for them to solder it on.

[HTH AMPS]

ribbon cable and push-on connectors have no place in an amp imo - soldered connections have worked in amps for decades with many of those amps still going strong.  the only reason to change is cost.

[jpfamps]

They look exactly like the power connectors in my PC, which I think are molex ones right?

Yeah I should've opened it up and checked it out first, might've saved myself some trouble.
It looks like the tech just super glued the problem connectors for the "fix", I knew it was too much to hope for them to solder it on.

Actually you can't really solder these connections very well (if at all), at best you get a botch which is just as prone to breaking — and it will take ages. Also hard wiring these connectors could cause servicing problems later down the line — ie you need to disconnect the Molex connectors to get the PCB out. My tactic now is to secure them with a dap of low-melt glue which can be removed at a later date.

My real bete noire is insulation disruption connectors (IDC). These rely on blades in the connection terminal to pierce the insulation of any wires inserted in them thus making the connection! As you can imagine these are prone to failure, and most Molex connectors are IDCs.......

A friend of mine used to roadie for several bands in the 80s who were using Akai samplers (yes I know the 80s were shocking). When these used to go down on the road he used to open them up an press at the Molex connectors in. This strategy was so successful one guy he worked for thought he was an Akai-trained engineer!

[silentrage]

Gotcha.
I think that's exactly what the service tech did to my amp, because now I see yellow blobs over a lot of the connectors that weren't there before. I guess they must be low melt glue.