music angel kt88 tube amp schmetic needed - diyAudio
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Old 21st April 2008, 03:43 AM   #1
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Join Date: Feb 2007
Location: victoria canada
Default music angel kt88 tube amp schmetic needed

I have a music angel tube amp model xd-se with kt88's. It is still under warrenty but emailing for the last week,I got no reply.I get hum on one channel only(seperate power supplys )so It looks like I will have to repair it myself.The hum stays the same no matter what the volume is so I'm thinking power supply(filter cap).Any ideas. swapped all tubes from other side and still hums(not a tube problem). I need a schmetic of mine to test further.Would a filter capacitor go so soon?The amp is about 2 months old with only about 10 to 20 hrs on it.
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Old 21st April 2008, 12:14 PM   #2
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Join Date: Dec 2005
Location: England
Default Here's it is!


Look at the link below for schematic as well mods for this amp.


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Old 21st April 2008, 01:25 PM   #3
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Join Date: Jul 2005
Location: North Derbyshire
Well it's a crude and simple circuit (and poorly made), but it should be simple to repair.

First off, try removing the preamp valves from the faulty channel, and see what effect either of those has on the hum? - to locate which stage contains the fault.

Although with an amp that new, I would suspect a manufacturing defect (not soldered something properly) rather than a faulty component. But isolating the stage the problem is in, will allow you to find the fault easier.
Nigel Goodwin
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Old 1st May 2008, 06:14 AM   #4
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Join Date: Feb 2007
Location: victoria canada
UPDATE:Since last time I got ahold of the seller.He was away and said it was under warrenty.I asked for a schmetic from him and got the same one that was on this thread.He said it was an old schmetic and that mine may have some improvements.None of the values for res or cap were the same.Here is some info.The triode switch operates 2 relays(j1-j2)When I last repaired electronics,relays were designated by k1 and k2.In the schmetic k2 is the switch for triode operation(we used to call switches s1 ect)This schmetic is almost useless but I found a bad filter cap(250v 180fd). It now works great. Thanks for the help.I asked the seller if he gets the new schmetic,to send me a copy and I will post it. Keith
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Old 1st May 2008, 08:44 AM   #5
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Join Date: Jan 2006
Location: uk
First mod I made to mine was to fit an earth. The earth point on the incoming mains plug was not connected.

I earthed the incoming mains plug to the chassis via one of the transformer legs with a biting washer.

Apart from re-biasing I have made no other mods to mine and it sounds very good indeed. I paid 90 + postage for mine about 18 months ago, originally intending to use it for parts...

absolute bargain!

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