Crate BT220H schematic

[jp3zone]

I'm repairing a dead Crate BT220H bass amp head, and am in desparate need of the schematics. Anybody got one?

Thanks

[Jazz P Bass]

Here is an older post for the BT50 schematic.
Link:http://music-electronics-forum.com/t19548/
The preamp appears the same.
The 220 has an FX loop & a balanced out.
Obviously the power supply & the output section will differ.
Short of this helping, try calling Loud Technologies.
LOUD Technologies Inc. Corporate Office
16220 Wood-Red Road NE
Woodinville, WA 98072 USA

Tel: +1 425 892 6500
Tel: +1 866 858 LTEC (866 858 5832)
Fax: +1425 487 4337

[jp3zone]

Thanks Jazz, I need the power supply section cuz the rail voltages a messed up, -0.95v + 1.5v. I dont see any voltage regulators, so it's all diodes & power resistors. I suspect the poweramp section might also be shot, so I need those specific schematics.

[Jazz P Bass]

Could it be that alien.
Then again, we are talking a Crate design.
Look in your amp.
What output IC are they using.
TDA7293 would be my guess.
The BT50 is using parallelled TDA2050's.
You should be able to separate the output section at the connector & see how well the power supply is doing when it is unloaded.
I would guess they used a higher voltage transformer & beefier resistors & caps.
There is a connector, J17, on the first schematic, top center.
I'll bet that is for the FX loop.
One pin is marked V+.
Disconnect the connector if you still have a loaded down supply.

[jp3zone]

Just pulled the heat sink off the power section and its using irfp9240 and irfp240 power mosfets. The power supply seems simple enough to sort out without schematics. I suspect the zeners are faulty causing the power supply to load down.

[Jazz P Bass]

MosFets.
Sure had me fooled
Anyway, good luck.

[Enzo]

WHICH power supply? The main power amp rails are not regulated, zener or otherwise, in any guitar amp I know.

If you mean the 15v rails for the preamp op amps, then instead of looking for two dead zeners, look first for an op amp intrnally shorting the rails together. Any look discolored or cracked? Of course two dead zeners is possible.

[Enzo]

Here, try these

[jp3zone]

Thanks Enzo, they look spot on! The power amp supply is fine, +/- 63v, the preamp supply is the dodgy one.I'm going to check for faulty opamps before I do any thing else, then go onto the power supply

[musashi]

Here, try these

Can you repost this?

[DrGonz78]

These might be the right files...