Functional check and repair of a Bose 1800 “Professional Solid State Dual Channel Power Amplifier”


bose1800 thermal cam

Fire in the disco


Two posts in one year? Is the world ending? Well, yes, but not just today.

I’ve been visited by a pair of handsome Bose 1800 amps over the past weeks. They needed a DC output delay / DC protection relays because apparently that tech did not yet exist in the mid 1970s. Those solid state devices were still a bit scary, I suppose.

Before you ask: no, this is not how I make money. I design embedded audio systems that you won’t see here because of confidentiality (but probably have seen in shops). Hopefully later this year we will have our first self funded products available. This was just a favor to a friend and interesting to me. Don’t ask me to repair your amps – I will just insult you with my hourly rates.

Of course nothing leaves here without paying their dues at the altar of measurement devices. Certainly over 40 year olds need a full workup including the ‘please bend over while I put my gloves on’ one. Except I use a hammer in the rear section – be glad I did not decide to be a doctor.

1800 from behind

Bend over please, and let me find my hammer


Number 1 presented a clean bill of health. Probably never smoked and played only multigrain, wholesome music. Number 2 clearly lived a more rock and roll life judging by his mechanical state. As we all know that made him more interesting and have a few defects, one of which being intermittent – guaranteed good filming material.

Video below – I’d appreciate you using the decentralized LBRY link over evil themtube. It’s not like they’re giving me money, anyway.

LBRY / Odysee





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