Ashdown replacement output board?

[Axtman]

I recently aquired an Ashdown Electric Blue 130 amplifier for cheap (free).

Not only is the output board blown but it was someone's DIY breadboard experiement. I will not be replacing components on the board because I do not trust it. Instead I would like to find a drop in board.....if possible. The board is powered by about +/- 62 volts and would put out about 130 watts into 8 ohms if working.



Unfortunately the speaker is blown but I have a speaker I can use. Luckily the preamp works.

Here is the schematic: electricblue130.pdf

[glebert]

If you have +/- 62VDC you should be able to try a really cheap class D module. Search Ebay for IRS2092. For that voltage they usually advertise those as 500W modules, you can get them for under $20 shipped. I've tried them in the past but ran into some odd signal or ground issues, but didn't really focus on it enough to try to resolve it and gave up. Others have had better luck than me.

[xtian]

I successfully used this one to replace a dead power amp in a JBL subwoofer. Works great! https://www.amazon.com/gp/product/B0893MBTW6

[Axtman]

I am toying with the idea of putting a Class D amp as the output board. It would be nice to find one with an auxillary power supply of +/-15 volts. It would be kind of strange to have a big hulking torroid transformer only to supply 15 volts to the preamp board. ;-)

[J M Fahey]

I´m old school (duh!) and would keep it similar to the original Class AB module.

Something similar to this would do nice.

https://www.ebay.com/itm/221287271767

https://www.ebay.com/itm/121457218844

or even:

https://www.ebay.com/itm/283166594720

2 transistors are enough but the 4 transistor one has extra safety rating.

You can mount transistors to current heatsink (if at all possible, show it),

You can remove the L bracket and mount transistors to heatsink using short wires, no big deal.

I bet you have less than +/-62V there, simply because it would be uncomfortably close to 63V cap rating, expect +/-50/55V tops.

Of course, you would use the original PT

[glebert]

^^ I would be really concerned the FETs are counterfeit/not rated as high as IRFPXXXX

[J M Fahey]

True in general, specially if EBay or AliBaba ones, but good/original BUZ90* (or their "brothers") are still available from Profusion UK

That if an original board needed repair, of course.

The perfboard version looks like an original clone, at least it shows 5 small TO92 transistors (a couple catastrophically burnt) and most probably a copy of the original Toshiba application example.