Kenny KA 6004 needs help

xpert54

Lost in Music
My KA 6004 has a problematic board in it. Its been repaired many times and it needs replacing. Board part number is X07-1120-00 or X07-112Q-00. This board was repaired by the previous owner, I should say butchered as his reapir left much to be desired.

The amp will work fine for a while then drop the right channel to a very low/fuzzy sound. Pulling the board and resetting it will fix the problem from any where to 6 months to a matter of hours.

I pulled the board and took it to Mouser Electronics and had one of their techs look at it as there were several discolored resistors in it. After much searching he found the right replacement parts. I replaced them, checked to board for bad solder joints and found several of those so I resoldered every one on the board to be sure all were done.

Amp worked perfect for about a year. Now that very same problem has started again. I'm thinking that it might be better to find a replacement board for this amp or a 6004 that is being parted out that has a good board in it

PM me or reply here, Thanks
 

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Are you 100% positive that THIS board is the issue? Reseating the board would simply renew the connection to the female card connector. Clean the contacts with a soft pencil eraser and shoot it with some DeOxit D5.

When the 'problem' pops up, go through the front panel controls slowly and methodically to see if any one of them brings things back to normal. This seems much more likely.

Something else to consider is that this unit (like a lot of gear made at this time) probably has a few C458 transistors. They need to go.
 
Having checked the controls when this problem started again I found that two of them cause a popping sound in the right channel when turned on and off (40hz and 80hz) switches. No problem with any of the others.

I blame the board as the source of the amps troubles cause I could pull it clean the contacts and all would work fine. It was only after repeatly increasing problems that I took it to Mouser and had their tech look at it due to the discolored resistors on the board.

After I had replaced the bad resistors and resoldered the solder joints the amp worked with out problems for nearly a year. the so called repair that the previous owner had done was to put a glob of solder on the contacts where the board inserted in the connector. This made the board fit very tightly and I believe stressed it causing it to distort and causing the stress cracks in the solder joints

I did file the globs of solder down to where there was very little left on the board did a very thourgh cleaning and made sure there were no possible shorts between the contacts. this was done at the time I replaced the resistors.

I did not think about any of the transistors causing a problem. I will need to get a schematic so I can locate them. thanks for your help
 
The excess solder should have been removed with a solder iron and solder wick. I'd have been very paranoid about taking a file or something like that to a PC board. In any event, the female card holder may have had its contact pins expanded beyond the point where it makes acceptable contact with the card.

These are the same type of edge connector that we used to use in the computer industry back in the 70's. When we had a problem, a few of the guys were able to use a small tool (like a dental pick) and claimed to be able bend the contacts back to usability...a desirable thing to accomplish, since many of these connectors had 100+ pins, and replacement meant desoldering and re-soldering 100+ wires (I usually just 'manned-up' and replaced the connector, which took a couple of hours). You might try to see if you can't salvage the connector with a similar procedure, if you really feel that the card isn't making good connection. I might also mention that the pin spacing is standard, so if push came to shove, you could probably find a replacement female connector that could be swapped in.
 
The 6004 seems to be working ok after a good deoxing and cleaning of the contacs, however I will keep looking for a another 6004 that is being parted out.

Thank you very much for your help
 
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