Sound techs and they're ability to DESTROY!

[philbaileymusic]

A friend of mine went to a venue in Darwen nr Blackburn and the sound tech decided to use the Preamp out of his Fender Deluxe 112 plus as a D.I out for the desk. Needless to say the desk lost a bank of channels (a nice bang) and my mate lost the primary of the transformer and a couple of tracks on the PCB.

I've sorted the PCB but Im struggling to find ANY info on the transformer. The primary was obvs 2 x 115/230 but I've no idea what the secondaries are. I think one is 30V AC (CP3 an CP5 connectors) but that was found looking at the 2 page schematic Fender issue on their website.

Anyone have a fender deluxe 112 plus and could either let me know what the secondaries are or maybe (carefully) measure them? Any info on the B-039357 transformer also would suffice. Also, Im new to posting on the site (or any for that matter) so if Im dreaming here of getting anywhere near the response Im after let me know!

Merci!

Phil

[pdf64]

'decided to use the Preamp out of his Fender Deluxe 112 plus as a D.I out for the desk. Needless to say the desk lost a bank of channels (a nice bang) and my mate lost the primary of the transformer and a couple of tracks on the PCB'
I can't see that would have caused a problem, unless the amp or desk already had a major issue, eg missing ground and power transformer primary insulation fault.
I had a Deluxe 90 1x12 combo in a while ago, but the guy has since emigrated.
It may help to give more detail on the amp, eg specify the model number or features.
It can be a problem getting Fender OEM parts in the UK.
Same PT as Princeton 112 plus?
http://support.fender.com/schematics..._schematic.pdf
Pete.

[Enzo]

They don't specify voltages because they expect when one fails you will order another 039357 and drop it in place.

But the schematic shows the amp to have 39.6v power rails, nominally 40 volts. So because it is a simple bridge, to get 40vDC, I'd need to rectify and filter about 28vAC. Make that 30 volts to allow for some diode junction drops. So you need 30vAC on either side, or 60v center tapped. Looking back at the schematic it even says 31.4VAC at the terminals on the board. So find yourself a 30-0-30 (60v CT) transformer of useful dimension, and there you go.

Schematic also says 94 watts at 4 ohm load. So you will need enough current capability to provide that.

[J M Fahey]

Agree and add.
The "useful dimension" means you must hunt for a 30+30V AC transformer (or 60V center tapped, it's the same) of around 2.5A current capability (2A will barely do, and if you can fit a 3A there it's even better) *or* around 150VA , which is another way of specifying it.
If in doubt post the link to the page you find and if you go physically to the shop, carry the old one, so (if possible) you get another, same-size, to ease mounting.
Good luck.

PS: and I doubt the connection from Pre Out can damage anything.
Something far worse must have happened.
I suspect the speaker out was involved, which *does* have the power to destroy a preamp input and die in the process.
A short strong enough to blow your own transformer means that your own power amp must be quite dead too, and also that some "not fuse" was used.
Build a lamp bulb limiter and check that all fuses are what's expected before turning that amp on.

[drewl]

???
The DI output into the desk should have worked okay, unless there was one hell of a ground loop.

[lowell]

Tempted to think the amp did the damage and not the desk. Just a thought, could be wrong.