Alto Mistral 900 schematic or ??

[km6xz]

Hi group, I got a Mistral 900 by Alto brought in that was disassembled and power transistors and hardware in a bag. I am in search of a schematic or at least an id on the power original power transistor. The guy put in a common pair (2SC5200 and 2SA1943 ) but the only original transistor in the bag is a ALTO TR-94N. I suspect it is a Darlington since the driver is pretty light weight which would explain why the guy gave up on it.
Anyone familiar with this amp?

[doctor]

Hi group, I got a Mistral 900 by Alto brought in that was disassembled and power transistors and hardware in a bag. I am in search of a schematic or at least an id on the power original power transistor. The guy put in a common pair (2SC5200 and 2SA1943 ) but the only original transistor in the bag is a ALTO TR-94N. I suspect it is a Darlington since the driver is pretty light weight which would explain why the guy gave up on it.
Anyone familiar with this amp?

In all Mistral series amplifiers only the 2SA1943 and the 2SC5200 transistors are used de facto.
Only quantity is different.

Compare two schematics for the same amp. The TR-93P is the 2SA1943 and the TR-94N is the 2SC5200.

Hope this help.

[km6xz]

Thank you very much Doctor! I assumed the 900 it was a much lighter weight amp since it only has one NPN and PNP per channel and the circuits in these prints have 4 of each. Looking back at my notes, I guess I worked on a 2500 earlier this year but it sure was a beefier amp than this one. Thanks for the confirmation about the 2SC5200 and 2SA1943's
The pc board has pads for one additional transistor be side of each channel but they are unused in this model.

Thanks a lot

[mozwell]

various mistral schematics, lets try firefox to upload, if that doesn't work, i am giving up.....

[km6xz]

Thank you Mozwell, you are a valuable resource here. You must have a gigantic collection of schematics.

When I moved here I had no idea that I might open a shop so did not make arrangements for shipping any schematics. I gave them away mostly to local hobbyist repair people but I am sure many went to a landfill since they filled a truck. Many of those I would ever have use for in any case like all the keyboard manuals or analog and digital tape decks. I have not seen a DAT machine here, let alone been asked to repair one. They might still be in service in the US where they were very common but musicians and home studios here only got involved after mechanical decks were obsolete. I still would enjoy working on DATs, ADAT and DA88 format machines because they were fun once their idiosyncrasies were were learned. Each of those transports could be rebuilt without effort or having to get hands dirty, unlike a large analog Studer, Ampex or MCI.

[mozwell]

always happy to help, all of the schematics i have are from the net, not from any personal service library. I am not a service tech, but an EE & musician with an interest in audio & guitar related things.

[tubeswell]

Thanks mozwell - my mistral 900 went south yesterday - time to pull out the soldering iron