Canadian 'Audio Design PA100' schematics needed

[junior35]

Hi,
I need assistance from fellow Canucks in posting schematics of Audio Design PA100 (or models 10A/20A) amplifier (early 80's).
Much appreciated.

[sakis]

Sorry for the arrogance but let me ask you Was it ever existing a Canadian Audio Design company ? well i presume not ...most of equipment i 've seen from that era and that place was renamed Japanese designs like sears did at the time ( nice machines though ...had a sears amp integrated that could easily do 100K square on my scope )

Id say post some pictures and may someone come up with something


Kind regards
sakis

[mickeymoose]

Sakis:

Clairtone Sound Corporation (good enough to be in the MOA in NY, look up "Project G"), Patterson Industries for speakers, Chisholm, mainly B&W TV, Electrohome Stereo & TV, Bryston, our own Planet 10 here, Ward-Beck (WBS) and not to forget a very active & large White Van Speaker industry!

Fellow Canadians: add to the list and prove Sakis wrong! E

[junior35]

Hi Sakis,
Here is some photographic evidence.
Cheers

[junior35]

Hi Moose,
And not to forget Classe Audio and Dayton Wright electrostatics.
Cheers

[sakis]

ok guys ...obviously the intention was a joke ...it is expected that from location aspect i cannot be familiar with Canadian manufacturers .

still the pcb looks familiar rings a far away bell What type of output transistors ?

Kind regards
sakis

[junior35]

Hi Sakis,
The outputs are 2n3773's . Basically the amp is still a virgin. It's my Dad's,so I didn't want to 'mess' with it all these years.But the time has come to 'change the oil and filter'. I'm thinking to do a basic recap and maybe new outputs (MJ21196?).
Regards,
Junior

[sakis]

well it all depends on the aspect

2N3773 is a fine piece of semi ...kinda slow but the all amplifier is not intended to be light speed

here is what i could do of the amp was mine ....

---Place a target IE it is important if the amplifier is intended to be a casual listening amplifier or a party animal
---In the first case where the amp is supposed to be for casual listening i could
*replace and/or beef up power supply caps
*replace all other electrolytics
*check soldering and general contacts issues
*verify /sample a few resistors to make sure not drifted values
*verify offset to 0 volt and bias to something reasonable 30-70 ma to my opinion
and now for the more hi end approach
**play with input filter and capacitors , play with miller caps to achieve a click of bandwidth ...just a click will do
**Keep the working semis ( seems that someones have been already replaced ) but only as long are same with each other

** Actually remove the additional pair of outputs since you may have a benefit from them like more capability at low loads but then all this is pointless since the trafo you have is too small for low loads and then if you try to increase speed and bandwidth you may not manage since the extra wiring of the extra transistors may not be able to support higher speed and/or bandwidth and you will eventually end up with an oscillator .( one thing you never never never do is to wire transistors away from the board and 10 times more worst to twist the cables of B-C-E 100 worst thing to do i s to twist both B_C_E )

a better approach will be a bit less power but better quality .... let us not forget that original 3773 is any way a quiet rugged device ...

In case of party animal find original transistors of your choice 3773 will be also dirt cheap and easy to find ( still be aware of fakes ) replace all since you have some that are not equal

replace capacitors plug n play !!

kind regards
sakis

[junior35]

Hi Sakis,
Thanks for your input. Actually,since I didn't have the amp next to me, I lifted photo's of an identical amp from the internet. My Dad's is really untouched, except that 25 years ago,because of amplifier turn-on 'thump' I added a simple and dirty refrigerator AC relay with big resistor to reduce the 'thump'.
Cheers

[tiefbassuebertr]

Originally Posted by junior35

Hi Sakis,
Here is some photographic evidence.
Cheers

good pictures.
I miss the bypass capacitors close at the PCBs.
This means long leads between the blue main capacitors and the voltage rail inputs at the PCB.