Acoustic 450 head trouble

[lc12345678]

Hi there,

I have an Acoustic 450 head that has blown 3 of the 6 output transistors. I was wondering if anyone has the schematics for the 450 head or any info on how to replace the blown output transistors. Any information would be great!!

[Don Symes]

This Unofficial Acoustic Control Corp Webpage is the only lead I have and the 450 ain't there.

Enzo or Ray Ivers probably have the real schematic ... but ... if you find a 12-device power amp among the designs, it was probably a power amp design common to at least a couple of preamps.

Hope this helps!

[Enzo]

I have it. The power amp is the same as on the 470 we discussed around here a while back. Board 170051.

This is a single sided amp. It runs on +92vDC. So it is quasi, and the speaker out runs through a large coupling cap.

If the outputs are blown, don't worry about finding more 480037 or whatever. I would just replace the whole pile of them with MJ15003, MJ15001, MJ15015, or your own favorite power semi of 120-140v and 15-20 amps. Just don't mix them. Make all six the same. If you replace three bad ones with something different, even if the old good ones are perfectly OK, they will not share current properly with strangers. Allied sells MJ numbers for under $5 each. Avoid the NTE crap.

If the predrivers are shot - the 40409 and 40410 - find the real thing. Again avoid NTE. NYE crosses with close specs, but the 40409/10 have integral heat sinks which the NTE do NOT. SO they will burn up.

If you can't find it, send me an email with Acoustic 450 schematic as the subject line to:

tmenzo at msn dot com

[acousticcontrolcorporation]

www.acousticcontrolcorporation.com

www.acousticcontrolcorporation.com

[gbono]

Doug,

Are you ever going to ship me the inductorsto fix the defective boards you sold me?