Somewhere on my website I state that this all started for me with a 20W ClassA amp my father and I built for a friend in the 1970's .......
Well, Nelson's not the only one who can find "interesting" old projects lying around 🙂
http://www.users.bigpond.net.au/mefinnis/passlabs/images/ca20_front.jpg
http://www.users.bigpond.net.au/mefinnis/passlabs/images/ca20_back.jpg
Haven't had a chance to fire it up yet, but hell I smiled when I found it !!!!!!
cheers, mark
Well, Nelson's not the only one who can find "interesting" old projects lying around 🙂
http://www.users.bigpond.net.au/mefinnis/passlabs/images/ca20_front.jpg
http://www.users.bigpond.net.au/mefinnis/passlabs/images/ca20_back.jpg
Haven't had a chance to fire it up yet, but hell I smiled when I found it !!!!!!
cheers, mark
"Wear safety glasses...." as Nelson also points in his ZEN articles : )
This one looks like it has been gathering dust for some time and I wouldn't much trust the electrolytics. They might "let out some steam" or literally explode.
I once blew up a much smaller cap, but what a BOOM.
Ergo
This one looks like it has been gathering dust for some time and I wouldn't much trust the electrolytics. They might "let out some steam" or literally explode.
I once blew up a much smaller cap, but what a BOOM.
Ergo
"Wear safety glasses...."
I blew a cap once too in 1980. I carry an artificial lens in my eye since then.😉
Whenever I run any project for a first time now I always wear glasses.😎
I blew a cap once too in 1980. I carry an artificial lens in my eye since then.😉
Whenever I run any project for a first time now I always wear glasses.😎
My experience with the big cans is that the vent plug
blows (watch out for that!) and an ultrasonic whistle
occurs which could deafen you, at least temporarily.
blows (watch out for that!) and an ultrasonic whistle
occurs which could deafen you, at least temporarily.
Once I used an old cap, it was dry but I didnt know it was, and i pug it in... BAM!! I was looking like a chicken with all that paper (or something similar..) from the cap on me and it was on the walls, now iam using all new caps, except for the ones I know how old are they...
Thanks for the general concern 😉
I will not just "flick the switch" .... I've been around a little longer than that!
No, we will sneak-up slowly on the unsuspecting beast with a variac ..... plus safety goggles and ear plugs !!!!
Schematic ?
http://www.passdiy.com/pdf/classa_amp.pdf
Colleting dust ???
Nope ... rats pooh !!
But in the end ..... it's all good fun.
Regards, Mark
I will not just "flick the switch" .... I've been around a little longer than that!
No, we will sneak-up slowly on the unsuspecting beast with a variac ..... plus safety goggles and ear plugs !!!!
Schematic ?
http://www.passdiy.com/pdf/classa_amp.pdf
Colleting dust ???
Nope ... rats pooh !!
But in the end ..... it's all good fun.
Regards, Mark
Wisdom After The Event
Mark, there was discussion here recently about running up old gear on a variac in short stages over a few days to allow electros to reform safely, elsewise you are risking high leakage currents causing internal heating and gas pressure and explosion.
http://www.vmars.org.uk/capacitor_reforming.htm might help.
Modern electros have a y shaped weakness on the top of the can and this allows these caps to expire gracefully.
Electros with smooth tops can be dangerous, as Peter can testify.
Over the years I have installed caps in reverse and caused cap explosions.
The can really does come off at bullet speed and if it hits a hard surface will mushroom or flatten - I nowadays habitually stand back with my head turned away at switch on - so far I have not been hit but I have had some really close shaves in the past.
Sorry to hear about you learning the hard way Peter, and your advice of safety glasses is good advice.
Eric.
Mark, there was discussion here recently about running up old gear on a variac in short stages over a few days to allow electros to reform safely, elsewise you are risking high leakage currents causing internal heating and gas pressure and explosion.
http://www.vmars.org.uk/capacitor_reforming.htm might help.
Modern electros have a y shaped weakness on the top of the can and this allows these caps to expire gracefully.
Electros with smooth tops can be dangerous, as Peter can testify.
Over the years I have installed caps in reverse and caused cap explosions.
The can really does come off at bullet speed and if it hits a hard surface will mushroom or flatten - I nowadays habitually stand back with my head turned away at switch on - so far I have not been hit but I have had some really close shaves in the past.
Sorry to hear about you learning the hard way Peter, and your advice of safety glasses is good advice.
Eric.
Boom!!!
I finished wiring. Turned on. Wow…what a nice sound!
Heck…? whenever I stepped up and down the attenuator
for the volume control, I heard the sound, “click!…click!…”
It was funny and strange. It was a new thing.
To fix the trouble, I looked over into the launched Zen V2,
for a close inspection of details of wiring arrangement,
without wearing the safety goggles.
Then, suddenly all happened!
A poor man was lazy in checking the correct polarities
of + and – of the output coupling capacitor.
I however comfort myself.
Even Mr Nelson P…hahaha. Even the artificial-lens-eye Pet…D…hahaha.
JH
I finished wiring. Turned on. Wow…what a nice sound!
Heck…? whenever I stepped up and down the attenuator
for the volume control, I heard the sound, “click!…click!…”
It was funny and strange. It was a new thing.
To fix the trouble, I looked over into the launched Zen V2,
for a close inspection of details of wiring arrangement,
without wearing the safety goggles.
Then, suddenly all happened!
A poor man was lazy in checking the correct polarities
of + and – of the output coupling capacitor.
I however comfort myself.
Even Mr Nelson P…hahaha. Even the artificial-lens-eye Pet…D…hahaha.
JH
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