KSA-50S ruined?

Patrik Floding · 18th August 2008, 11:32 PM

Hi all!

I just sold my FPB-200 in favour of keeping just my beloved KSA-50S.

Only problem was that the output relay on the right channel of the 50S needed fixing or replacing. Today I disassembled the KSA-50S, cleaning the output relay of the right channel. I also removed some dust, and then reassembled the thing.

It fired up as normal, and sounded fantastic.
HOWEVER, the LEDs that show current bias level kept being lit (both red and blue LEDs) to show that full bias was on (on both channels), and after some time the amp was extremely hot. Too hot to keep switched on, and the thermally controlled bias shut down didn't kick in either.

I don't even know where to begin fault searching. Did I blow up something on the logic board behind the front panel, perhaps? Is there a way to disconnect things from the front panel to force lower bias level.. (Assuming the logic board at the front controls this functionality.)

It's just a daunting task to try to fix this without risking to create more problems.

Is there an expert on the KSA-50S out there who might like to help me against compensation?

I'm also looking for a replacement KSA-50S to tide me over, and as a fallback solution should things keep going pear shaped..

Regards

Patrik Floding · 19th August 2008, 07:17 AM

I guess a start would be to try to find the complete schematics for the KSA-50S, including the logic board. I tried googling it, but no result. Anyone has any ideas?

I'm gutted.

Zero Cool · 19th August 2008, 01:55 PM

I would carefully go back and retrace your steps. Its easy to have left something disconnected, or for a wire to come off unknowingly. or something to have gone back on backwards. Go slow, take your time and look it over good and see if you see anything out of the ordinary. 9 times out of 10 its something simple.

Patrik Floding · 19th August 2008, 04:48 PM

Thanks for the advice!
Unfortunately I'm pretty sure nothing like that happened. However, I did some stupid things, on the assumption that the circuits were stone cold (no power). I'll go into the details if anyone wants them!
Regards

18th August 2008, 11:32 PM	#1
Patrik Floding diyAudio Member Join Date: Jun 2005 Location: UK	KSA-50S ruined? Hi all! I just sold my FPB-200 in favour of keeping just my beloved KSA-50S. Only problem was that the output relay on the right channel of the 50S needed fixing or replacing. Today I disassembled the KSA-50S, cleaning the output relay of the right channel. I also removed some dust, and then reassembled the thing. It fired up as normal, and sounded fantastic. HOWEVER, the LEDs that show current bias level kept being lit (both red and blue LEDs) to show that full bias was on (on both channels), and after some time the amp was extremely hot. Too hot to keep switched on, and the thermally controlled bias shut down didn't kick in either. I don't even know where to begin fault searching. Did I blow up something on the logic board behind the front panel, perhaps? Is there a way to disconnect things from the front panel to force lower bias level.. (Assuming the logic board at the front controls this functionality.) It's just a daunting task to try to fix this without risking to create more problems. Is there an expert on the KSA-50S out there who might like to help me against compensation? I'm also looking for a replacement KSA-50S to tide me over, and as a fallback solution should things keep going pear shaped.. Regards

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Ruined transformer?	madisqbu	Tubes / Valves	7	17th April 2008 01:33 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

19th August 2008, 07:17 AM	#2
Patrik Floding diyAudio Member Join Date: Jun 2005 Location: UK	I guess a start would be to try to find the complete schematics for the KSA-50S, including the logic board. I tried googling it, but no result. Anyone has any ideas? I'm gutted.

19th August 2008, 01:55 PM	#3
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	I would carefully go back and retrace your steps. Its easy to have left something disconnected, or for a wire to come off unknowingly. or something to have gone back on backwards. Go slow, take your time and look it over good and see if you see anything out of the ordinary. 9 times out of 10 its something simple.

19th August 2008, 04:48 PM	#4
Patrik Floding diyAudio Member Join Date: Jun 2005 Location: UK	Thanks for the advice! Unfortunately I'm pretty sure nothing like that happened. However, I did some stupid things, on the assumption that the circuits were stone cold (no power). I'll go into the details if anyone wants them! Regards

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)