How to set Power transistors on Kenwood ka-5500?

Lipaso · 29th January 2007, 06:16 PM

I instaled new power transistors in my ka-5500 and they are very hot after few seconds. How to set them?

please help

janneman · 29th January 2007, 06:38 PM

Do you have a schematic or a pic of the board? Can you identify the bias adjust pot?

Jan Didden

Lipaso · 30th January 2007, 12:41 PM

I instaled new power transistors in my ka-5500 and they are very hot after few seconds. How to set them?

please help

richie00boy · 30th January 2007, 12:45 PM

Jan has already responded, asking the question again and ignoring his useful advice is not going to get you very far.

ilimzn · 30th January 2007, 01:43 PM

And are you sure that:
1) Power transistors were the only part that needs change?
2) That the BIAS was set to the lowest position prior to installing new transistors?

Lipaso · 30th January 2007, 02:48 PM

Sorry I thout, that I wrote this post in wrong place and I write it again in other place. Probebly moderator changed this and paste it here. This schema is to big i added onely a piece of it. There are variable resistors (BIAS) but i don't know what voltage on which element should be. Power transistors are 23, 24, 25, 26.

BIAS are not on the lowest position.

sorry Jan

thanks for help

richie00boy · 30th January 2007, 03:08 PM

You need to turn the bias pot so that the voltage across the output device emitter resistors is as low as you can get. This will mean setting the pot to lowest resistance.

Then increase the pot a bit at a time. You need to aim for about 25-33mV across the output device emitter resistors.

Tube_Dude · 30th January 2007, 03:38 PM

Quote:

Originally posted by richie00boy
You need to turn the bias pot so that the voltage across the output device emitter resistors is as low as you can get. This will mean setting the pot to lowest resistance.

Then increase the pot a bit at a time. You need to aim for about 25-33mV across the output device emitter resistors.

Hi richie00boy

Everything you wrote is correct , except that for minimum current across the output devices , the pot must be set at is highest resistance value.

richie00boy · 30th January 2007, 06:49 PM

Yes sorry, squinting at the schematic I got the transistor the wrong way round.

Lipaso · 31st January 2007, 09:14 AM

Thank You very much.

29th January 2007, 06:16 PM	#1
Lipaso diyAudio Member Join Date: Jan 2007 Location: Gdañsk	How to set Power transistors on Kenwood ka-5500? I instaled new power transistors in my ka-5500 and they are very hot after few seconds. How to set them? please help

29th January 2007, 06:38 PM	#2
janneman diyAudio Member Join Date: May 2002 Location: Where Germany, The Netherlands and Belgium meet Blog Entries: 6	Do you have a schematic or a pic of the board? Can you identify the bias adjust pot? Jan Didden __________________ /Another new issue: Linear Audio Volume 3!

30th January 2007, 12:41 PM	#3
Lipaso diyAudio Member Join Date: Jan 2007 Location: Gdañsk	How to set Power transistors on Kenwood ka-5500? I instaled new power transistors in my ka-5500 and they are very hot after few seconds. How to set them? please help

30th January 2007, 12:45 PM	#4
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Jan has already responded, asking the question again and ignoring his useful advice is not going to get you very far. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

30th January 2007, 03:08 PM	#7
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	You need to turn the bias pot so that the voltage across the output device emitter resistors is as low as you can get. This will mean setting the pot to lowest resistance. Then increase the pot a bit at a time. You need to aim for about 25-33mV across the output device emitter resistors. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more


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30th January 2007, 01:43 PM	#5
ilimzn diyAudio Member Join Date: Feb 2005 Location: Zagreb	And are you sure that: 1) Power transistors were the only part that needs change? 2) That the BIAS was set to the lowest position prior to installing new transistors?

30th January 2007, 06:49 PM	#9
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Yes sorry, squinting at the schematic I got the transistor the wrong way round. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

31st January 2007, 09:14 AM	#10
Lipaso diyAudio Member Join Date: Jan 2007 Location: Gdañsk	Thank You very much.

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