K-502 Left Channel is out - diyAudio
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Old 21st March 2008, 03:41 PM   #1
udailey is offline udailey  United States
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Default K-502 Left Channel is out

I just assembled the kit. First run it worked great. I was excited... its my first DIY. I had trouble with the pot on second run and decided to replace it since all solder joints were good. I replaced the pot with a radio shack A100KX2. Its a 100kOhm .5W Dual pot. I grounded it with the lug. I turned on the amp and had lost the left channel totally, except that it still pops when powered up. All tubes glow. I replaced the pot with an exact match to the B100K that it came with. Still the left channel is missing.
I got out the multimeter and tested every resistor and cap. I think the multimeter is bad (its a chinese cheapy from ebay). Maybe I need to get another, but multi's that read caps up to 2ooouF are expensive. It read many caps and resistors but some of them it would not read AT ALL. I figure a bad cap will still give some reading and a bad resistor should still have some resistance.
I have yet to hook it up to the transformers.
So far, any suggestions? Has anyone dealt with this before?
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Old 21st March 2008, 04:33 PM   #2
udailey is offline udailey  United States
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Well, I had removed the first pot and used a copper braid solder wick to remove the solder. I was again using the multimeter and working through all caps and resistors when I noticed that there was a tiny piece of that copper braid shorting two legs of the pot on the left side. I removed it and still no music out of the left channel. So while the amp was on I wiggled each wire (I soldered 6" 24gage copper wire legs from the board to the pot). When I wiggled the wires the RIGHT channel went out and I could hear a faint bit of music coming from the left. Dear lord give me patience and a better soldering hand.
So I will resolder all those joints and see what happens. Probably should use a another new pot just for good measure.
I will post results within the hour if my parents dont show. They will be here soon for Easter Weekend. I hope you all have a fun and happy Easter
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Old 21st March 2008, 04:53 PM   #3
kevinkr is offline kevinkr  United States
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Sounds like colder solder joints galore. You heat the joint and flow the solder, allow at least several seconds for this to happen.

Try this site for some general guidelines (best I found in a quick google): www.elexp.com/t_solder.htm
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Old 21st March 2008, 05:12 PM   #4
udailey is offline udailey  United States
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Kevin,
Yeah I think thats what happened. Plus I had used solid copper core wire to solder with and I have no idea if that helped cause bad joints but this time I used some multi thread wire and it works like a charm !! Thanks for your response and it works great now! Cant wait for my Dad to listen to some of his music on it.
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