KBA/15 circuit diagram

[chartman]

Is this available? I'm a retired electronics engineer and looking tio fix this amp as a hooby project

[chartman]

OK the transformer is gone... anyone know the spec? ( no answer from Peavey) Or the DC voltage powering the TDA2040 ?

[j0nsnell]

20volts at 1.5A ir 20V/A will fit nicely. https://uk.rs-online.com/web/p/chassis- ... rs/0504650
18volts will also work OK. https://uk.rs-online.com/web/p/chassis- ... rs/0504583

[chartman]

20volts at 1.5A ir 20V/A will fit nicely. https://uk.rs-online.com/web/p/chassis- ... rs/0504650
18volts will also work OK. https://uk.rs-online.com/web/p/chassis- ... rs/0504583

Thanks for that. I did consider that and similar from Rapidonline.com
However, I had a brainwave... Fit a 24V 1A smps ( from eBay ) for £6. I bench tested that with my bench supply @ 24V DC and it works fine.! Connect +Ve to the outside pin on the 2 pin AC connector , Neg to the inside pin. Power loss is minimal.
As an option, I could connect to the DC side of the bridge and get another ~2.5V into the power rail. However, I'd have to rewire the on/off switch and the power on LED. Not worth the effort.
The 'boost switch' seems to have negligible effect... what should I expect? I've checked the switch and it's good and appears to switch in a resistor...
Thx for the suggestion.

[j0nsnell]

The boost switch connects a 470p capacitor through a 4k7 resistor between pin 2 of IC1A and ground.
That increases the gain above 6kHZ by 3dB.
Check the earth leakage on your fleabay power supply ... they can be iffy.

[chartman]

Thx, I'll check the leakage... BTW the SMPS is 2Amp not 1 Amp. I'd post a picture for future reference but it's beyond me how to do it

[j0nsnell]

2Amps at 24volts is ideal.
To add a photo, needs a link to the photo and beyond me!

[chartman]

All done and tested. Works fine. Was able to adjust the 24V to 28V so all good! Pots all good and sounds great. Well pleased for £13+£4 postage