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-   -   need Kenwood KA-990EX service manual (http://www.diyaudio.com/forums/solid-state/101197-need-kenwood-ka-990ex-service-manual.html)

tino96 3rd May 2007 02:06 PM

need Kenwood KA-990EX service manual
 
Hi, from some years i'm searchin' schematic or service manual of vintage Kenwood KA-990EX.
Someone can help me?
many tnx in advance
http://img235.auctions.yahoo.co.jp/u...27pc161368.jpg pc161368.jpg

K-amps 4th May 2007 01:13 PM

Thats an underrated amp... very tight bass for a small amp. Try and your hands on the KA-1100, 2200, 3300. (all 150wpc).

tino96 4th May 2007 03:11 PM

Quote:

Originally posted by K-amps
Thats an underrated amp... very tight bass for a small amp. Try and your hands on the KA-1100, 2200, 3300. (all 150wpc).

yeah.. it's a very good amp, 10/20 W in pure A class and abiding 100 W. rms pc ...but without schematic or servce m.. :bawling: :bawling: :bawling:

p.s.
were I can take schematics of KA-1100, 2200, 3300?
bye

K-amps 4th May 2007 04:06 PM

Is the amp broken or what?

tino96 9th May 2007 10:35 AM

Quote:

Originally posted by K-amps
Is the amp broken or what?

Hi K-amps, the amp is now broken...
tree times broken.. :(
tree time repaired by technical centre of Kenwood, but make back same problem.

now I want replace the final stage with this...
(and I don't want give more to Kenwood... :( )
http://users.swing.be/edwinpaij/imag...lisimpleV2.gif

http://users.swing.be/edwinpaij/ampli_mosfet_simple.htm


but I need schematic or service manual...

K-amps 9th May 2007 01:24 PM

That is one amp that is not good for mods. (I may be wrong but it has a DLD (class-H) output stage right?

Meaning if you replace it with another OP design, the existing heatsink will not be adequate.

Post a Picture of the heatsink and surrounding components and I can confirm if that is the case. I know all other Kenwoods of that era were class-H. i.e KA-880, 1100, 2200, 3300 etc.

tino96 9th May 2007 03:38 PM

Quote:

Originally posted by K-amps
That is one amp that is not good for mods. (I may be wrong but it has a DLD (class-H) output stage right?

Meaning if you replace it with another OP design, the existing heatsink will not be adequate.

Post a Picture of the heatsink and surrounding components and I can confirm if that is the case. I know all other Kenwoods of that era were class-H. i.e KA-880, 1100, 2200, 3300 etc.


U'r wrong, it has 2 powerpacks, no PWM, no oscillators....
.......and very BIG heatsink .....

Nigel Goodwin 9th May 2007 04:02 PM

I've got a paper manual, it's a SERIOUSLY complicated design, the actual output devices are KAB01's, which includes four power transistors, two run off +/-35V, and two off +/-64V - they are fed in turn by two driver IC's, TA2030. The TA2030's are fed from what looks almost like a complete amplifier in itself (with 18 transistors), except the emitter resistors are 150 ohm, and outputs are taken off both emitters.

It's got a pretty nice spec though!

K-amps 9th May 2007 04:09 PM

Quote:

Originally posted by tino96



U'r wrong, it has 2 powerpacks, no PWM, no oscillators....
.......and very BIG heatsink .....




Based on Nigel's details, Tino it seems YOU are wrong. :devilr:

I may be no EE or expert but in terms of hours logged on these DLD Kenwoods, I have a bit.....


The TA2030's are class-H switchers, the dual rails also confirm it is like all other of the same era. They are used in the KA-880, 1100, 2200, 3300, M1, M1a, M1d.

I tried to rebuild an M2a (220wpc) making it a monoblock and removing the switching circuit (TA2031) . The amp lasted 15 beautiful minutes and the sinks were over 90C with very little bias I had used 16 2sa1943/ C5200's Thermal runaway was very quick. That heatsink is rated for class-H, not regular class-B.

The M2a had +/-91 and +/-56vdc rails and used the higher V rated TA-2031.

The KAB01's are like the Sanken DAT's the other models use. Paralleled trannies in once package to save space.

tino96 9th May 2007 04:35 PM

I have the amplifier... i'm not wrong...:rolleyes:

this ampli is 25 years old....

how old are U?

p.s.

weight..... 13.9kg

do U've never seen a 100+100 w H-class amplifier??


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