Another Kenwood KA-7100 recap

All the toggle switches in this and like units are fairly difficult to clean in large part because of the orientation of the switch mechanics. Inside you have a plastic molding with slots that covers up the pins and the two sliding contacts. Spraying deoxit D5 in with the unit right side up probably isn't going to do the job as well as you'd hope. Ive improved my success by flooding the switch in the small gap at the rear between between the phenolic base and the metal body quickly turning the unit or board with the lever pointed downward and then working the switch. This allows more cleaner to go inside the slots where its needed.
 
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1-2-3-4 -> NC Contacts
5-6-7-8 -> NO Contacts
9-10-11-12 -> Common
13-14 -> Coil

The NC contacts are not used.
 
My dad had one of these when I was growing up. It was always cranked up running both a pair of heresys and a pair of white van speakers. It did great until it broke in the early 00's-wish I knew what happened after that :(
 
Here is a list of the parts to re-cap these amps, along with some other parts (protection relay, trimmers, relay driver transistor and diode, heatsinks for power supply transistors, uprated power supply resistors).

If you cut and paste this into Notepad, Wordpad or similar text editor, but save it with the extension CSV, you should be able to import it into Excel.

Interestingly enough, the cost of all these parts at Mouser comes out to around $75. But people baulk at paying $200 if you tell them that's what it will cost to re-cap their amp.

Lee.

Kenwood KA-7100 capacitors,,,,,

Part Number,uF,V,Notes,Mouser Part,Sort Order
,,,,,
Main Board,,,,,
19,10,25,,647-UKW1J100MDD,1
20,10,25,,647-UKW1J100MDD,2
21,10,25,,647-UKW1J100MDD,3
22,10,25,,647-UKW1J100MDD,4
15,10,50,,647-UKW1J100MDD,5
16,10,50,,647-UKW1J100MDD,6
17,10,50,,647-UKW1J100MDD,7
18,10,50,,647-UKW1J100MDD,8
41,10,50,,647-UKW1J100MDD,9
39,100,16,BP,647-UES1C101MPM,10
40,100,25,LL,647-UKL1V101KPDANA,11
25,100,35,,647-UKW1V101MED,12
26,100,35,,647-UKW1V101MED,13
27,100,35,,647-UKW1V101MED,14
28,100,35,,647-UKW1V101MED,15
29,470,50,,647-UKW1H471MHD,16
30,470,50,,647-UKW1H471MHD,17
31,6800,50,15mm lead spacing,647-UKW1J682MRD,18
32,6800,50,65mm high,647-UKW1J682MRD,19
33,6800,50,30mm diameter,647-UKW1J682MRD,20
34,6800,50,647-UKW1J682MRD ,647-UKW1J682MRD,21
bypass caps for mains,,,4 x 1uF film,5989-100V1.0-F,22
,,,,,23
Front board,,,,,24
3,330,10,,647-UKW1E331MPD,25
4,330,10,,647-UKW1E331MPD,26
5,47,10,,647-UKW1V470MDD,27
6,47,10,,647-UKW1V470MDD,28
7,10,16,LL,647-UKL1V100KDDANA,29
8,10,16,LL,647-UKL1V100KDDANA,30
17,10,16,LL,647-UKL1V100KDDANA,31
18,10,16,LL,647-UKL1V100KDDANA,32
19,3.3,25,LL,647-UKL1H3R3KDDANA,33
20,3.3,25,LL,647-UKL1H3R3KDDANA,34
21,10,16,LL,647-UKL1V100KDDANA,35
22,10,16,LL,647-UKL1V100KDDANA,36
23,3.3,25,LL,647-UKL1H3R3KDDANA,37
24,3.3,25,LL,647-UKL1H3R3KDDANA,38
25,0.33,25,LL - was tant bead,647-UKL1HR33KDDANA,39
26,0.33,25,LL - was tant bead,647-UKL1HR33KDDANA,40
27,330,25,,647-UKW1E331MPD,41
28,330,25,,647-UKW1E331MPD,42
,,,,,43
Back board,,,,,44
3,100,16,,647-UKW1V101MED,45
5,47,10,,647-UKW1V470MDD,46
6,47,10,,647-UKW1V470MDD,47
15,220,6.3,,647-UKW1C221MED,48
16,220,6.3,,647-UKW1C221MED,49
17,3.3,25,LL,647-UKL1H3R3KDDANA,50
18,3.3,25,LL,647-UKL1H3R3KDDANA,51
19,220,25,,647-UKW1V221MPD,52
20,220,25,,647-UKW1V221MPD,53
,,,,,54
Resistors,,,,,55
65,220,,replace with 2w,71-CPF2-F-220-E3,56
66,220,,replace with 2w,71-CPF2-F-220-E3,57
77,100,,replace with 2w,71-CPF2100R00FKE14,58
78,100,,replace with 2w,71-CPF2100R00FKE14,59
,,,,,60
Trimmers,,,,,61
VR1 - 4,500,,replace with multi-turn,652-3296Y-1-501LF,62
,,,,,63
,,,,,64
,,,,,65
Miscellaneous,,,,,66
Qe34,2N3904 replace with,1 x,relay driver transistor,512-KSD1616AGBU,67
De27,replace with,1 x,relay diode (1N4004),625-1N4004E-E3/73,68
,,1 x,cap across power switch,81-DE2F3KH103M,69
,,,cap across power switch (better),539-104M06QC100,70
,,1 x,relay,653-MY4-02DC24,71
,,2 x,heatsink for PSU transistors,532-577304B00,72
,,4 x,thermal insulators,739-A15036002,73

leesonic and all. Sorry to drag up an oldish thread but I am picking up my good condition 7100 on the weekend and was wondering if this list of items was still current and valid? I appreciate all the hard work that's gone in to creating this list and will use it to create a Mouser order if its a great list of SKU's to get the amp back in to "fresh" condition.

Basically I was looking to freshen up all the parts that would require it with as close to OEM as possible (not looking for significant upgrades, however happy to replace with improved parts).

Thanks in advance!
 
It looks like Leesonic's parts list on page 1 should all be available at Mouser.

That was the plan. I assume it's all good as a freshen up, vs a major upgrades? I wasn't sure if the list included any crazy hop up parts or if it was a mild resto list.

For $100 odd I'll order all the parts and have them here for when the amp arrives and I look to freshen it up.
 
That was the plan. I assume it's all good as a freshen up, vs a major upgrades? I wasn't sure if the list included any crazy hop up parts or if it was a mild resto list.
Nope, no crazy mods. In some cases as a personal choice I would choose differently, such as 105 degree caps (Nichicon PW or Panasonic FR for example) in the power supply. Also, you can replace these two with film caps instead.
25,0.33,25,LL - was tant bead,647-UKL1HR33KDDANA,39
26,0.33,25,LL - was tant bead,647-UKL1HR33KDDANA,40

But I want to make clear, these are not criticisms or anything negative I'm saying, just that the list can be used as is, or as a starting point. Hopjohn also had a very nice set of posts of his KA-7100 restoration with photos, you should check those out too. He has good ideas, as well as many others here. I have learned a lot, starting from zero experience, from all the posters, and continue to do so.
 
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leesonic and all. Sorry to drag up an oldish thread but I am picking up my good condition 7100 on the weekend and was wondering if this list of items was still current and valid? I appreciate all the hard work that's gone in to creating this list and will use it to create a Mouser order if its a great list of SKU's to get the amp back in to "fresh" condition.!

Nothing really has changed from that list. Anything that's in the signal path (identified as Nichicon KLs) I now use Wima films if they are physically small enough, otherwise a KL bypassed with a 1uF Wima.

Again, it's down to opinion, but there's no need to run 105C caps in the power supply because they don't get hot. Ever felt a cap running at 85C? I doubt any of us have, except where there has been a fault in the circuit.

Lee.
 
Again, it's down to opinion, but there's no need to run 105C caps in the power supply because they don't get hot. Ever felt a cap running at 85C? I doubt any of us have, except where there has been a fault in the circuit.
That's true, I think it's more that these 105C caps have a longer projected life. But we will probably expire before they do, lol.
 
That's true, I think it's more that these 105C caps have a longer projected life. But we will probably expire before they do, lol.

Searching for 6800uF 63v Nichicon caps, the two that are rated at 105C have a projected life of 1000 hours (VY and VZ series), whereas the 85C ones have a life of 2000 hours (VR, FW and KW series). Go figure. Personally, I'd rather go with an "audio grade" 85C cap than a "general purpose" non-audio grade cap. It might all be smoke and mirrors, but I think Nichicon are a more respectable manufacturer, and wouldn't just try to up-sell on the audio grade name. The price difference is negligible anyway.

Bottom line, any new caps by a respectable manufacturer and bought from a trusted source will make these things sound a lot better. The original caps will be getting on for 35 years old now.

Lee.
 
Hey Lee, my mistake for not being clearer - when referring to the PS, I was thinking of the smaller cap values. I specifically mentioned using caps such as Nichicon PW and Panasonic FR. I used 6800uf KT caps at your suggestion and am perfectly happy with them.

Just picking the 470uf/50v cap as an example, the specs on Mouser list these life specs:

Panasonic FR - 10,000 Hours
Nichicon PW - 7,000 Hours
Nichicon KW - 2,000 Hours

And they are all good caps. Now the poor guy who asked is going to be hopelessly befuddled with this taste of cap arcana. Don't let this sidebar deter you from updating your system.
 
With regard to the main filter caps the KW and FG are about the only reasonable leaded option that's widely available for this spot and I prefer the KWs there. KWs are fine elsewhere in the supply, but I suppose ESR and ripple specs are a little better with say FR, FM, FC or if you like your Nichicons then HE or PW, PM. Differences in these probably comes down to the can size, bigger diameter usually being a bit better where there are differences apples to apples. All of these are 105 degree BTW.
 
Hi Lee, working on my own 7100 today and wondering what you added to the main power supply 6800uf caps on the bottom of the board. It looks like you have a film capacitor bridging the + to - soldered on the bottom of the board.
Wondering what's up with that?
Also just messing around inside looking for noisy transistors I noticed that if I grounded the two backs of transitors you added heatsinks two any and all noise dropped to zero.
 
I noticed that if I grounded the two backs of transitors you added heatsinks two any and all noise dropped to zero.

I believe Q31,Q32 transistor heatsinks are tied to the collector. You might not want to ground them. Did you measure the voltage of these? they should be close to b+ and b-.

7100PS.JPG
 
Hi Guys, thanks for all the help and pictures. Just wondering about the 1uf bypass caps for the mains soldered on the bottom of the board to the leads of the 4 6800uf caps.
what's the thought process for adding these film caps?
 
Hi Guys, thanks for all the help and pictures. Just wondering about the 1uf bypass caps for the mains soldered on the bottom of the board to the leads of the 4 6800uf caps.
what's the thought process for adding these film caps?

Makes you more attractive to the opposite sex?
Improves your gas mileage?
Whitens your teeth?

Seriously though, bypassing the big electrolytic capacitors with smaller film ones is supposed to reduce some kind of noise. I don't know if it's true, but the caps are cheap enough to try.

Lee.
 
Just wondering about the 1uf bypass caps for the mains soldered on the bottom of the board to the leads of the 4 6800uf caps.
what's the thought process for adding these film caps?

there is a wikipedia page that might help or just google.
 
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