Kenwood KA-8100 power cord missing....

Bobbyd218

New Member
Good Day Audio Nuts,
I decided to take a shot on the bay and purchased what I hope doesn't turn out to be a boat anchor. The KA-8100 will make a nice combination to my KT-8300 if the reason the power cord is cut off was just that some banana wanted to salvage the copper. But then again, I would not have gotten the amp for 76 bucks local pick up here in CT had it been in working condition.

Anyway, I could use some general advise. Just removing the strain relief grommet is a huge pain, and before I scuff up that black paint any more, perhaps someone could share a method better than using a pair of pliers. My next attempt will be a vise grip.....

The power cord comes in and attaches to the nearest of the three power receptacle outlets. It's a tight fit there, and my 45 watt desoldering iron isn't budging that stuff. I'd appreciate some advise.... I'm considering two other options. One would be to snip off the wire as close to that junction as I can, and heading to the farthest terminal away where there is more room to work. I'm not sure that is even possible.... Another would be to cut the cord closer to the inlet of the amp, and make a junction from the wire there to the new cord. Don't know about that one either, ha...... OK, tell me the error of my ways and how to do it correctly!!!

On another note, there was a sticker with two invoice #s where the amp had been serviced by Electronic Service Labs in Wethersfield, CT. I contacted Jeff there(had talked with him once before) to get an idea of what had been done and when, but the service was prior to his records being computerized. So he has no idea.... I'm hoping that this cord is the only huge issue at the moment. The amp does look pretty clean with no visible burns or bulging. I do recognize the age of this nice piece, and that it would benefit from a major overhaul. But first things first....

Thanks for your help, guys.....
 
cord grip can be got out be squeezing from the back inside the unit .its not easy but will come out .
its best to solder in the new one to where the old one is .so the old one is completely gone .
you could solder the new to old and use shrink-wrap or you could use wire nuts .
i would test the amp for shorted outputs etc before plugging it in .
 
+1 on what pete said

check outputs first because you may decide not to fool with the power cord if you have blown outputs. you could sell the amp even with some blown outputs and a cut power cord

and please don't try to splice a new power cord to the end of the old one. that is an accident (or a fire possibly) waiting to happen. you may need to borrow a more powerful soldering iron and some wick to do the job

KA-8100 is a very respectable unit and worthy of some effort. hope you are able to get it working :thmbsp:
 
The power cord comes in and attaches to the nearest of the three power receptacle outlets.

For testing purposes you could make a power cord with two male ends - plug one end into the amp and the other into the wall.
 
Thank you for the suggestions, guys...
Would you please walk me through the procedure for testing the outputs and what are acceptable tolerances. I do have a DMM, and have used it only sparingly.

"For testing purposes you could make a power cord with two male ends - plug one end into the amp and the other into the wall."

Thanks gort69, that sounds pretty good..... Might try that one out; plug into amp before live circuit or my hair may curl somewhat....
 
the basic test for transistors is whether or not they are shorted. that test is done without power

there is a sticky thread by EchoWars in the DIY forum here about testing transistors

also, any time you suspect blown outputs or are not certain, it is commonly accepted practice to use a DBT (dim bulb tester) when first powering up to limit potential collateral damage. There are many threads here on DBT that can be found by searching. In your case though, I believe I would check them as described in EchoWars' thread and not by powering up the amp. The cut-off power cord is very suspicious.

welcome to vintage audio :) it is a continual learning process. not to fear though, there is usually help available and when there is not, determined AK advanced search and/or google search of AK can almost always yield the information you need. KA-8100 should be fairly easy to work on and well worth the effort. I have a KA-7100 (one step down from your amp) that I have recapped and it is a strong and beautiful sounding amp.

good luck with your project
 
Last edited:
have you looked at fuses inside the amp?

any blown fuses? not blown but replaced? original looking and intact?
 
Thanks Roger...
I've been involved with vintage stereo for some time, but have very limited experience trying to rectify problems. My best accomplishment to date fixing electronics was TV related. My father and I have the same model older flat screen Samsung. When mine had problems, I paid over $300 to have the mother board replaced. At the time, these were still going for about a grand. Dad's started having the same symptoms, so I did some research. YouTube was instrumental in helping me to fix his problem by identifying and replacing the bulging caps that were bad. That's when I bought my soldering iron, and purchased the caps for less than $10 from Parts Express. So I saved Pop a 300 dollar bill with my first ever soldering job. Wish I had done that for myself, ha....

I'll look for Glen's posting about testing outputs..

And yes, that power cord idea sounds like as much fun as back feeding your house with a generator during a power outage..... ZZZZZZZZZTTT One should be VERY careful not to end up with a serious injury....

I'll take a look at the fuses inside..... I could have sworn I saw some solder keeping them in place, but I'll check again.. My vision isn't what it used to be......

Thanks..
 
Definitely look at the fuses before going any further. That is a basic investigation procedure that may yield some clues.

Beyond that I am honestly not certain which way would be best for you to proceed.

To test the output transistors I am not sure whether they would need to be removed, but if so then they would need new grease and possibly new mica insulators when reinstalled. If they can be tested in place I don't know whether you would be able to gain adequate access to do so.

Going the other route, using a DBT can tell you if something is shorted (probably would be output transistors I believe). The DBT is a method of wiring a light bulb in series with one side of the AC power to the unit under test. A DBT can be constructed inexpensively from basic home wiring parts. (many threads here that give build instructions). Using a DBT, when powering up a healthy amp the bulb will glow brightly initially and then dim down after a couple seconds. If outputs are blown the bulb will continue to glow brightly. If you decide to use the DBT then the double male ended AC test cord described by gort69 might work for temporary testing purposes, but you would have to make sure that the cut ends of the original power cable are not touching each other or anything else.


And that is about the extent of the help that I am able to offer here. Except to repeat that you should not splice the AC cable as a permanent solution, and to suggest that you report back the condition of the fuses. Are they intact or blown? Do the values match what is printed on the board? Do they look original?

Also I think pete is right-on about squeezing the inside of the strain relief connector to remove the original AC cord. Maybe cut the cable flush with the connector and push it inwards.
 
Last edited:
The fuses looked intact. And yes, someone hit them with solder.....Probably because they're vertical and possibly fell out at one time. I'm not aware of another reason.

I believe I can get to the transistors without removing them. I'll have to go look at that sticky again.... I think I'll need a better DMM...

Time to fetch my vice grips and try to remove that strain relief tab....As Toby has said, "I'm not as good as I once was", ha.....

As always, thank you..
 
Yes, I'll probably need a more professional iron than the Shack model that I have. There are so many different Weller models out there. I saw quite a few on Amazon, and Home Depot has one in a case; 100/140 watts for a bit over $30. Any recommendations, Warren?
The vice grip hasn't worked much better.... Perhaps I'll try drilling out the middle so it will compress when squeezed.....

Thanks,
Bob
 
Last edited:
Yes, I'll probably need a more professional iron than the Shack model that I have. There are so many different Weller models out there. I saw quite a few on Amazon, and Home Depot has one in a case; 100/140 watts for a bit over $30. Any recommendations, Warren?
The vice grip hasn't worked much better.... Perhaps I'll try drilling out the middle so it will compress when squeezed.....

Thanks,
Bob

I believe 100/140W is what I have.
I always remove the cord clamp with a pliers, from the outside. Just be careful. The pliers would tend to move away from the panel when they slip off. If you're worried you could cut a hole in a thin piece of plastic and put that over the cord clamp to protect the panel, or use some packing tape.
 
Thanks Warren,
I'll head to Home Depot and see if they have it in stock....

I did take my drill to the cord clamp, reamed it out, and was able to remove it with ease.
Finally, a small victory...
 
Just got home. Confirmed, my gun is 100/140W. Very useful for tube gear and soldering grounds to a chassis, bus bars, other big stuff.
 
Well, I'm armed and dangerous with this new soldering gun. I won't do any work until there's better light tomorrow. Then I'll get some new cord and rig up a DBT. That will take a few days......I'll keep you guys posted, thanks..
 
Finally got some help with the 8100 this afternoon. I had put it aside for a few weeks while I tried to work out my electronic frustrations, ha... I ran into a friend at breakfast who got me started with this hobby some years ago, and he said to bring the amp to him and he'd see if he could fix it. Turned out that the cord was probably cut because the power switch was intermittent, even after spraying it out. Luckily, he had a spare in his inventory..... Brought it up to power slowly, and the relay clicked in. It's up and running right now as I write this. Many thanks to Dave S for your fine work, as well as all you AKers who chimed in....
 
Last edited:
Glad to hear that you were able to get your amp working again :thmbsp:

Thanks for keeping us posted. Enjoy your KA-8100! Wouldn't mind having one of those myself...
 
Back
Top Bottom