Sonab 4000P Information


2020-01-23 3:15 am
I found the diyAudio forum when I was looking for info on the Sonab 4000P amplifiers.

My son, who is a collector of vintage HiFi and electronic keyboards asked me to check out his three (yes, 3!) 4000P units, none of which currently work.

As a semi-retired electrical engineer, I have reasonable experience with electronics, both in my career and having built my own amplifiers and speakers from scratch in my younger years.

My biggest issue at the moment is trying to source obsolete components, mainly transistors, or their current substitutes. eg, I note that the main power transistors on the circuit diagram are 2N3055 (easily obtainable), however the first 4000P I opened up has Motorola 7320001's, for which I have yet to find any info on.

Mind you, these may still be OK, it was just a visual check before I test them and the other transistors.

The diyAudio forum has limited info from persons who have had (or may still have) the 4000P amplifier, (the threads are about 10 years old!), and I would be pleased to hear from them or any others who can assist.


2013-07-05 1:12 am
I have two P4000's in the shed when I find some spare time, so if you need to compare/check
voltages etc... Suggest build a Dim Bulb tester then, after you've completed visual checks,
power up with DBT and Variac and monitor psu voltages and bias, but of course you
know this...