C Audio Model CA2

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   Came home a couple of nights ago and discovered one of these out by the bins minus its lid/top plate. Obviously no harm in bringing it in to see if it at least turns on i thought...Dug out a kettle lead and it turned on fine, both channels work and it's now been added to the "found collection" and is now chugging along happily in the corner powering another special from the found collection.

Now back to the point of posting - i've had a pretty good search trying to find some info on this amp but haven't managed to come across anything and figured surely one/some of you guys must have encountered one at some point?

(Please excuse the poor quality image)

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Crop Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 December 2011 Location: The Batcave Status: Offline Points: 15	Post Options Post Reply Quote Crop Report Post Thanks(0) Quote Reply Topic: C Audio Model CA2 Posted: 21 February 2012 at 8:42pm
	Came home a couple of nights ago and discovered one of these out by the bins minus its lid/top plate. Obviously no harm in bringing it in to see if it at least turns on i thought... Dug out a kettle lead and it turned on fine, both channels work and it's now been added to the "found collection" and is now chugging along happily in the corner powering another special from the found collection. Now back to the point of posting - i've had a pretty good search trying to find some info on this amp but haven't managed to come across anything and figured surely one/some of you guys must have encountered one at some point? (Please excuse the poor quality image)

Pin2Hot Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 01 March 2011 Location: GB Status: Offline Points: 18	Post Options Post Reply Quote Pin2Hot Report Post Thanks(0) Quote Reply Posted: 21 February 2012 at 10:13pm
	What a lucky find!! These were produced around 1985, there was a 400Watt@ 4Ohm per channel and a 250Watt version both housed in a 4U case. I think a smaller 100W version was introduced later. Badged versions were produced for others companies including the Rauch Powerblock and Avitec Beta, I did have a disgram for it but haven't seen it in years, the circuit design did however follow the Hitachi mosfet application note fairly closely. Hope that Helps

BUZguy Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 17 November 2011 Location: South Wales Status: Offline Points: 323	Post Options Post Reply Quote BUZguy Report Post Thanks(0) Quote Reply Posted: 21 February 2012 at 10:32pm
	+1 great little find! So if it does have Hitachi TO3 fets in, how many are in there? they could be numbered with J48, J49, J50 or J56 and K133, K134, K135 or K176

Crop Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 December 2011 Location: The Batcave Status: Offline Points: 15	Post Options Post Reply Quote Crop Report Post Thanks(0) Quote Reply Posted: 21 February 2012 at 11:11pm
	4 x K135 4 x J50

BUZguy Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 17 November 2011 Location: South Wales Status: Offline Points: 323	Post Options Post Reply Quote BUZguy Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 8:27am
	prob 250w per ch then. 500w for 0 pence! can't argue with that!

service dept Steve Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Registered User Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 1452	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 10:01am
	Is that left hand capacitor leaking? Might cause problems later if it is. Although I must say I haven't had one through the door it does look (as mentioned earlier) to be the same as the Rauch (IIRC shared personnel at some level or other) for which I do have a full set of drawings if required. The Rauch (Ironically German for "Smoke") did use the Hitachi design, the later versions using mountains of the now long gone flatpack mosfets.
	We are not "they", We are "the others" - http://www.servicedept.co.uk -

Crop Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 December 2011 Location: The Batcave Status: Offline Points: 15	Post Options Post Reply Quote Crop Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 12:05pm
	Yeah that is a leaking capacitor you can see, the whole thing's filthy inside, god knows why the previous owner removed the top or why they threw it out for that matter! Those drawings would probably be handy to have if you wouldn't mind?

service dept Steve Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Registered User Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 1452	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 12:58pm
	It appears to be a "power block 44" the drawing is here: http://i932.photobucket.com/albums/ad166/servicedeptsteve/DSCN6136.jpg
	We are not "they", We are "the others" - http://www.servicedept.co.uk -

BUZguy Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 17 November 2011 Location: South Wales Status: Offline Points: 323	Post Options Post Reply Quote BUZguy Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 8:32pm
	Interesting circuit. almost identical to the Maplin mosfet amp 5 transistor driver stage. at dc rails of +/- 73v using small transistors - I wonder how hot they run. I prefer it when TO126 type are used for the 3 nearest the fets. e.g. MJE340 / 350

service dept Steve Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Registered User Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 1452	Post Options Post Reply Quote service dept Steve Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 8:49pm
	It will look just like a very great deal of mosfet amps both old and new as the "Hitachi" design was the definitive design and was used with success in many amps like bk, Rauch, maplins modules, early matrix, etc, if fact it would be easier to list those that didn't use it! (HH springs to mind)
	We are not "they", We are "the others" - http://www.servicedept.co.uk -

BUZguy Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 17 November 2011 Location: South Wales Status: Offline Points: 323	Post Options Post Reply Quote BUZguy Report Post Thanks(0) Quote Reply Posted: 22 February 2012 at 9:02pm
	The circuit uses 9v zener + 1N4148 network between the gate and source. the Maplin amp didn't have this. Variants of output devices had this in built didn't they? there was another similar Mosfet module available in the early 90's from Cirkit Distribution which did use them, think it was a 12v zener. 9v zener will limit the output a bit I think?

Earplug Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 03 January 2012 Location: Europe Status: Offline Points: 693	Post Options Post Reply Quote Earplug Report Post Thanks(0) Quote Reply Posted: 23 February 2012 at 5:29pm
	I´ve seen both 10v and 12v zeners used. I suppose it depends how safety minded you are. I don´t think you´ll lose that much power compared to what you lose due to the high Drain to Source saturation voltage...
	Earplugs Are For Wimps!