What to do w/ Kenwood KA-5700 w/ blown outputs? - diyAudio
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Old 10th September 2010, 06:26 PM   #1
rongon is offline rongon  United States
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Default What to do w/ Kenwood KA-5700 w/ blown outputs?

I searched and found nothing relevant...

I have a really clean and nice-looking Kenwood KA-5700 integrated amp that's been sitting in my closet for over 15 years. I blew the outputs in one channel by shorting the speaker leads with the amp on (dumb, I know). I've asked around and it seems the output transistors were D587A and B617A, of a special shape different than TO220.

First off, does anyone know of transistors that could substitute for the original D587A and B617A output devices? They're way obsolete, and I can't seem to find them for less than $20 each (ouch). I'd like to get an idea of how much physical modification and rejiggering would be necessary to retrofit TO220 or similar transistors... I don't want to make this a major project.

The other alternative is to sell it for parts on eBay or something, or offer it up here for anybody who would like a really clean KA-5700 chassis. If someone here really wants it, all I'd be looking for is to cover the cost of shipping.

Thanks.

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Old 10th September 2010, 07:52 PM   #2
infinia is offline infinia  United States
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Yea those outputs are oddball.
You might be able to fit some TO-220's (40-50W) but the design would be on the edge for +/- 40V DC rails. It's rated for 40 watts but most likely can output~ 70W at clipping.
You will also have to replace more (special gain driver) transistors, besides the 2 outputs. Check the diode string nearby, if they are bad then it would NOT be worth the effort, unless you have skills to re-adjust the fixed bias.
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Old 10th September 2010, 09:50 PM   #3
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I need a 2SB618A for a Harman Kardon receiver. No longer available, that batwing design. I'd retrofit but the chip would have to be very close.
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Old 14th September 2010, 03:45 AM   #4
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i have some pulled from a working amp... i have to go check exact part, but it was batwing style
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Old 10th January 2014, 12:35 AM   #5
srinath is offline srinath  United States
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A Kenny soverign VR-5700 turned up @ my door.
I seem to have a burnt feeder cable to the power amp board (I think it is the problem) It seemed to have slow cooked and melted where it twists by the transformer, nothing burnt looking, but just twisted into a pretzel and hardened ...
This amp does everything its supposed to @ start up, the clicks and the flashing mute and this and that, but does not make a sound.
I know its an old thread, but any ideas on this amp ?
The amp board is the one of the right as you're facing the receiver right (the one and only one attached to a heat sink right ? Has anyone had something like this happen ?

Thanks.
Srinath.
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Old 10th January 2014, 01:34 AM   #6
srinath is offline srinath  United States
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My 5700 worked briefly after I tapped the case ...
Then when I moved it into place and connected up speakers etc, it didn't work.
I think I have a loose connection somewhere, tomorow I'll try it again. The burnt wire I think is a loose wire ...

BTW I have none of these batwing transistors, I seem to have a lot of B1875's ... I couldn't read the numbers too well in the dark with my flashlight ...

Cool.
Srinath.
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Old 19th January 2014, 01:46 PM   #7
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You will have to modify, as in drill some holes, but the 2sa1302 and 2sc3281 will sub for the B617A and D587A respectively. In NTE or ECG cross they are the ecg 2329 and ecg 2328 respectively.
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