Ka-7020

ohsteve

Member
Hi folks, I have a Integrated amp the Kenwood KA-7020. I have found that the two main power caps may be blown, I am sure one is as I can see electrolyte oozing out from under onto the main board. The other cap has some how got jolted and broken the soldered connection to the main board breaking the path lines that are etched onto the board, I am trying to figure out how to repair this, but in the mean time I need two of these caps...they say on the side that they are...'For Audio ELNA

(3) 7 1v15000mF (M)
(2)(4) NC
(-) Negative
C E (85 degrees C) JAPAN

They are listed on the board as C103 and C104 in the power supply section.

Any help with these would be greatly appreciated.
Please email at ohsteve1@sbcglobal.net.
Steve
 
Last edited by a moderator:
You need to take some measurments. Diameter and length. Screw terminal or solder post.
 
and double check that voltage rating. 71V doesn't make a lot of sense.

Once you have all this info, head on over to Digikey or Mouser and start digging.

Nice amp if you can get it running again!
 
Thanks guys, I am just going by what is on the side of the can, Cap is 3 inches by 2 inch diam. Four post soldered. Post 2 and 4 are not connected, I was puzzled by the voltage also..has a 7 space 1v15000microfarads which I thought very high but with 350 watts of output power and two power transformers and eight out put transistors this thing is a monster...lol. sold originally for $1000 in 1970. I am wondering if maybe I missed connecting all the contact points that the traces went to. As you can some what see on the attachments I am holding one of the caps but the flash keeps making too much reflections, but you can make out the space between the 7 and the 1; next is the top of the main board where C104 was the board is cracked, but it doesn't seem to go through. The next one shows the bottom of the board where the solder connections tore the traces off the board.

When I measured with multimeter across 3 and - the caps seems to be charging and when reversed they seem to be discharging...which leads me to believe that the caps may be ok and just need to wire around points where traces are torn.

I am going to try that, will let you know if it works or if I let more smoke out of the components.

Steve
 

Attachments

  • 40600011.jpg
    40600011.jpg
    31.6 KB · Views: 50
  • 40600013.jpg
    40600013.jpg
    59 KB · Views: 44
  • 40600015.jpg
    40600015.jpg
    49.5 KB · Views: 36
Last edited:
Why doesn't 71v make sense?

How about 6.3, or 63v or 35v?

Its a 15,000 uf @ 71v cap.

They are what they are. You'll have to go up to an 80 or 100 volt cap. Never, never, never go undervoltage! Tons of you-tube vids of exploding caps that are fed a high than rated voltage!:eek:
 
For some reason, didn't see the pictures the first time I read your post, so will clear up a few things for you.....


Those two broken pads are not electrically connected, they are just stabilizing points. The other two pads look fine.

More than likely what you say was electrolyte was probably glue. I've worked on more than a hundred pieces of vintage gear, and have never seen them ooze. Unless they've popped open! They'll dry up before anything.

There are several places to obtain free service manuals on the web, but if you need a tech to work on this, they'll want one that's easy to read, which most of the free ones aren't. Buy an original somewhere if at all possible.

And, your piece of gear is closer to 1990 than 1970, and has a rated output of 100W per channel, not 350. That's a dynamic rating; my wife's hair dryer is rated at 1500w.:lmao:
 
Here You may have to get creative mounting these, or hell, they may go right in. There a little shorter, but what tha hell.
 
Thanks again guys, sorry for the mistype, 1990 it was supposed to be, and the 350W is the power rating...duh!. Sorry about the poor pictures I have a very early 4 megapixal camera doesn't focus well. I have had a few caps blow on me but most of those were voltage oreinted, have found a few that spewed their guts out all over the inside of unit. As far as this amp goes until I can find schematics I have to put it aside. Both caps tore out the traces, wasn't until I tried to remove the second one that I found it the same as the first, must have been dropped or very severely jarred.
From using all my exotic test equip. (multimeter) it looks like the caps were wired pos1 to neg2 and pos2 to neg1 and every thing else traces off from those. From what I can see and test the output transistors all look fine.
Ovaeasy, most of the vintage gear I have worked on has been tape decks/VCR's/ or ones that have had blown pwr supplies from plugging in to wrong voltage (overseas)
mostly I worked on military equipment and there I at least had decent test equip to trouble shoot. I really hate to give up on this, but it was free to me. Unless these caps went bad inside, but they charge when I put the meter on them and discharge when I reverse leads.... I guess I will have to order the caps and see if they work...other than that I am stumped as this was working and then just died. I'm gettin' too old for this...

Steve
 
Well, here is an invitation to anyone who would like to take a shot at this to fix, just send me the shipping cost and I will send you this for you to fix and keep or sell. I am stumped and to damned tired to continue on with it. Let me know and we can work it out.
Steve
PS thanks for all the help.
 
Well, guys I persevered and reglued the caps back onto the board then soldered wire the same size as cap leads bent them over and soldered to the traces on the board and bingo the unit came up and worked....I am now a happy camper, now I am not sure I want to sell it or keep it to pwr up one set of my many speakers.

Steve
 
You might want to power up some speakers before you decide. I have a KA 7010 which is rated at 100 wpc. I think the 7020 is rates higher - 110 wpc? It's a nice amp and able to power difficult 4 ohm loads. If anything, I'd say it's very neutral sounding - fairly understated on the bass, but nice presence. I drive a pair of Polk SDA 2s with mine and can push them to punishing listening levels. Because the Polks can put out some pretty good bass, I generally have the tone control up or loudness button on. There's a decent phono stage on that amp too - both MM and MC settings. For a 90s integrated, it defies the BPC moniker put on a lot of equipment like this. They were only offered in Europe and on military bases there so they don't show up often here.
 
Hi folks, I have a Integrated amp the Kenwood KA-7020. I have found that the two main power caps may be blown, I am sure one is as I can see electrolyte oozing out from under onto the main board. The other cap has some how got jolted and broken the soldered connection to the main board breaking the path lines that are etched onto the board, I am trying to figure out how to repair this, but in the mean time I need two of these caps...they say on the side that they are...'For Audio ELNA

(3) 7 1v15000mF (M)
(2)(4) NC
(-) Negative
C E (85 degrees C) JAPAN

They are listed on the board as C103 and C104 in the power supply section.

Any help with these would be greatly appreciated.
Please email at ohsteve1@sbcglobal.net.
Steve

Tryin' to understand something, the manual says as in the picture attached:

attachment.php


I would expect a voltage not a capacity...:scratch2:

Paolo
 

Attachments

  • kenwood.png
    kenwood.png
    5.5 KB · Views: 25
Back
Top Bottom