Hello. Just signed up here as I'm (finally) getting back into building amps. Been in electronics as a career since about 1973. The main aspects of my career were split between high power broadcast engineering and high end instrumentation repair (about ten or more years in each). I built my first diy amp in 1978. A nice little 50W RMS per channel model that I made lots of horrible mistakes on and it still showed up as one of the cleanest amps tested at a Marantz clinic I dragged it into. I just knew it blew my socks off compared to my old top end Radio shack receiver. Since then I built several more of basically the same model for myself and others. One ran bridge mode as the resident sound system of a 3000 sq/ft pool hall and had over 16,000 hours on it without a failure when it was finally taken out of service when the place closed (might be running still, I just lost track of it then). Anyway, hello. I'll be posting here again in the future as I get up to speed again on building some projects. Doc
I spent a couple of years doing the depot repair and cal thingie until they contracted it out.
16,000 hrs.?????? that's wayyyyyyyyyy to good for around here - most of us blow ours up adjusting the bias current.
Well - OK - the truth is that I'm the primary one that blows things up. However I chalk that up to my Navy training - I was a surface to air missile tech. 🙄
Welcome to the insanity here!!!! Lots of good things to look at. 😀😀😀
Echoing the comments of the others, welcome to our forum! Sounds like you have quite some varied experience. 😀
Building reliable amps shows you have the knack.. Hope you find plenty to interest you here.
Building reliable amps shows you have the knack.. Hope you find plenty to interest you here.
Thank you all for the warm welcome. C2cthomas; Was at least 16,000 hours. Ran up to 16 hours a day, for twelve years, which is closer to 35,000 for seven day weeks, but I recall they were closed on Sunday or some such. Errored on conservative side. I did blow up my share of amps though. Most exciting was having a bias pot open up which sent both power devices hard to the rails in opposition to each other. They didn't like that and turned into three lead shorts. Kevinkr; My experience was indeed varied. From crawling through grocery store attics and sevicing old McMartin SCA and Bogen PA sound systems to servicing pinball machines and the earliest video games. Went to Atari TTL school on first Pong and Tank games. Much later I attended HP & Tek spectrum analyzer repair seminars. Then Harris and Larcan transmitter schools. On the instrumentation side I repaired virtually every known type of test equipment. Worked for legendary Haltek in Mountain View (Silicon Valley, CA) then for two years at Test Lab Company after it was spun off from Haltek. High end was 150GHz (don't get excited. thats pretty simple; it works, it don't, ship it to Hughes.) But did repair some pretty bizzar stuff. Oddest problems were things like a conductive fungus in BNC connector or a phase gain meter that was in spec everywhere but exactly at 100Hz. (Was skipping an entire band and phase lock on band bellow and above was almost good enough to meet spec except at the very end of their lock ranges... that one took a while to find.) Anyway, glad to be here. Doc
What you want? Loudest boom? A shorted contactor in a CCA 20,000 Watt transmitter. Bringing it up after a tube swap. Ears rang for ten minutes. Most visual damage? Shorted filter cap on -26KV line in Townsend transmitter. Reduced entire bank of 200W ceramic surge resistors to little pile of shrapnel in bottom of walk in rack cabinet. Most expensive oops? Slipped with a scope probe and shorted a 70V burn supply to a 5V logic supply and blew up 22 IC's on an early Data I/O prom burner.... without a proper schematic. (fixed it!) Tied menetarily with missed step on cal procedure on an HP8411 harmonic converter. Cost $1200 for HP to recheck it themselves after I rejected it. Doc
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