KA-9100 - overhaul

S

Siviuze

New Member
I bought a ka9100 which is in not so bad condition: the amp is working on every channels/inputs (well after a kontakt 60 cleaning on all switches/knob :thmbsp:) and is in good cosmetic condition.

However, I can hear hiss with this conditions:
- on phono input, gain at 0 and knob at mid level - audible at 5m
- on aux/tuner input, gain +10dB and knob at 3/4 - audible at 2m

Here're some pictures of the beast :D






I also find that the trebles are 'crushed'. Finally, VU meters bulbs do not light always immediately and sometimes you have 5-10min before they decide to light up.

Any ideas?
 
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Hi,

I just got one 2 months ago..,very nice sounding amplifier. Mine has lost channel issue. EW suggest me to clean the ports and it works. The amplifier is still in orginal condition. Regarding the lights,one of the meter is more brighter then the other,suspect blown bulb. Other then that it works great
 
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I'll do it as soon as possible (a shot of kontakt 60 + rag should be enough right?)

I raised the question of the interest of a recaps (especially for the trebles). Is it worth the shot?
 
The noise may be a regulated supply that needs rebuilding (new transistors, caps, zeners). The treble issue is probably dirty switches and/or a speaker relay that needs replacing.
 
OK so here's a first draft of a semiconductor BOM for the KA9100. I didn't find every equivalent for now (and I'm not sure for the others).

power supply..............equivalent..........stats
Qk1 - 2SC1983
Qk2 - 2SA755...........BD240C
Qk3 - 2SC945(Q)
Qk4 - 2SA673A
Dk1-5 - W06B .......1N4005
DZk1 - Zener YZ-140...TZX14B-TAP........14V 1/2W

Diode
Qz1 - 2SC945(Q)
Qz2 - 2SC1212A(C)
Qz3 - 2SC945(Q)
Dz1-8 U05C
Dz9 - W06B................1N4005
Dz10-12 - 1S2076.......1N4148

Power Amp
Qe1-4 - 2SC1775
Qe5-8 - 2SA912
Qe9-10 - 2SC1400
Qe11-12 - 2SC1885
De1-2 - Zener EQA01-24 1N5252B 24V 1/2W
De3-6 - S2076...........1N4148



Abouts the caps of this boards, I think I'll do the replacement with the Panasonic FM series. Is this OK?
 
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:lurk: Watching with much interest as I too have a recently acquired very nice condition 9100 in need of a facelift. It will be interesting to see how it fares against my new Marantz PM8004.
 
Here a more complete BOM with some potentials equivalents:

ID Original reference potential equivalent info

power supply
Qk1 2SC1983 TIP112
Qk2 2SA755 BD240C
Qk3 2SC945(Q) KSC1845
Qk4 2SA673A(C) or (D) KSA1013YBU
Dk1-5 W06B 1N4005
DZk1 Zener YZ-140 TZX14B-TAP 14V 1/2W

Diode
Qz1 2SC945(Q) KSC1845
Qz2 2SC1212A(C) STX715
Qz3 2SC945(Q) KSC1845
Dz1-8 U05C
Dz9 W06B 1N4005
Dz10-12 1S2076 1N4148

Power Amp
Qe1-4 2SC1775
Qe5-8 2SA912
Qe9-10 2SC1400
Qe11-12 2SC1885
De1-2 Zener EQA01-24 1N5252B 24V 1/2W
De3-6 1S2076 1N4148

control
Qi1-2 2SK68A(L) FET
QI3-4 2SK68A(M) FET
Qi5-6 2SA850 or 2SA777 KTA1274
Qi7-10 2SA847(G)
Qi11-14 2SA640
Qi21-24 2SK68A(L) FET
Qi25-28 2SC1345 or 2SC1328
Qi29-30 2SA899 MJE350
Qi31-32 2SC1904
Di1-4 1S2076 1N4148

Meter
Dh1-2 1N34A
Dh3-4 1N60IFT


cap series
power supply
Nichicon PW
Nichicon DK
Panasonic FM

diode
Nichicon PW
Nichicon DK
Panasonic FM

power amp
mix (general purpose + sound specific - silmic/FG/pureism)?

control
mix (general purpose + sound specific - silmic/FG/pureism)?

meter
Nichicon PW
Nichicon DK
Panasonic FM


Next question: I guess it's better not to touch certain components but how do you know what to keep and what to change?
 
Siviuze said:
OK so here's a first draft of a semiconductor BOM for the KA9100. I didn't find every equivalent for now (and I'm not sure for the others).

power supply..............equivalent..........stats
Qk1 - 2SC1983
Qk2 - 2SA755...........BD240C
Qk3 - 2SC945(Q)
Qk4 - 2SA673A
Dk1-5 - W06B .......1N4005
DZk1 - Zener YZ-140...TZX14B-TAP........14V 1/2W

Diode
Qz1 - 2SC945(Q)
Qz2 - 2SC1212A(C)
Qz3 - 2SC945(Q)
Dz1-8 U05C
Dz9 - W06B................1N4005
Dz10-12 - 1S2076.......1N4148

Power Amp
Qe1-4 - 2SC1775
Qe5-8 - 2SA912
Qe9-10 - 2SC1400
Qe11-12 - 2SC1885
De1-2 - Zener EQA01-24 1N5252B 24V 1/2W
De3-6 - S2076...........1N4148



Abouts the caps of this boards, I think I'll do the replacement with the Panasonic FM series. Is this OK?
Click to expand...
For me I am now using Panasonic FR/FM

Good Luck on this upgrade...The Caps in back of the faceplate are a Bit*h to work on.

I had pickup a 9100 last year...I put it back together as I was not going to deal will this(9100 will be a Parts Unit.). Have the 8100 and It's a breeze to work on.
 
On the KA-9100, the original caps are solder-tab. And because these tabs slip directly into two small circuit boards for attachment, any other cap diameter and any other mounting style are going to be a real problem to mount.

Michael Percy Audio sells a Nichicon KG Gold 10,000µf 63V solder-tab cap that measures 40mm x 80mm. Works great in the 9100. They also sell a 15,000µf 63V KG Gold (40mm x 100mm) that will work, but I'd not use them in the 9100 unless I was prepared to make a thyristor modification to protect the power switch. Probably would be a good idea to modify even if the 10,000µf caps were used.

The protection circuitry is such a PITA to get to that I always replace ALL the diodes and transistors on that small board when I get it loose. Wayyyy too much trouble to put it all back together and discover that there's an issue.
 
If it takes time for the bulbs to light up, there might be a bad power switch in there. If this is the case, it must be replaced - asap.
 
Michael Percy Audio sells a Nichicon KG Gold 10,000µf 63V solder-tab cap that measures 40mm x 80mm. Works great in the 9100. They also sell a 15,000µf 63V KG Gold (40mm x 100mm) that will work, but I'd not use them in the 9100 unless I was prepared to make a thyristor modification to protect the power switch. Probably would be a good idea to modify even if the 10,000µf caps were used.
Click to expand...
Thank you for the tip ! What would be the interest of the 15000uF caps? (since it's needed a mod + it cost twice the price of the 10000uF caps).

If it takes time for the bulbs to light up, there might be a bad power switch in there. If this is the case, it must be replaced - asap.
Click to expand...
I think I'll do the thyristor modification: I guess this should resolve the problem (without changing the switch).
 
Siviuze said:
What would be the interest of the 15000uF caps?
Click to expand...
Not sure what you mean, but the final decision on what cap to use is yours.

The switch doesn't have a lot to do with the meter lamps, other than that the switch allows current flow to the primary of the transformer, which allows current flow to the secondary, which allows current flow to the lamps.

FYI, the lamps are in series. If one goes, they both go. They are 8V 150mA lamps, and because they are resistively current limited, any substitution here may be problematic. AK member Dgwojo should have the proper lamps.
 
Sorry for the delay I was on holiday.

Thank you for the clarification about lamps. I'm wondering if there is simply a bad contact. I'll try to find a way to reproduce the problem.
 
A feedback from my tests: it is a bad contact. The bulbs go on and off when I tap (softly).

I also forced the filter buttons to the off position with a short circuit and magic! The hiss is strongly reduced and the trebles are here again!

The big overhaul seems unnecessary now, so it is deferred to the next problem.

Anyway, thank you for your help and your support :)
 
Siviuze said:
Here a more complete BOM with some potentials equivalents:

ID Original reference potential equivalent info

power supply
Qk1 2SC1983 TIP112
Qk2 2SA755 BD240C
Qk3 2SC945(Q) KSC1845
Qk4 2SA673A(C) or (D) KSA1013YBU
Dk1-5 W06B 1N4005
DZk1 Zener YZ-140 TZX14B-TAP 14V 1/2W

Diode
Qz1 2SC945(Q) KSC1845
Qz2 2SC1212A(C) STX715
Qz3 2SC945(Q) KSC1845
Dz1-8 U05C
Dz9 W06B 1N4005
Dz10-12 1S2076 1N4148

Power Amp
Qe1-4 2SC1775
Qe5-8 2SA912
Qe9-10 2SC1400
Qe11-12 2SC1885
De1-2 Zener EQA01-24 1N5252B 24V 1/2W
De3-6 1S2076 1N4148

control
Qi1-2 2SK68A(L) FET
QI3-4 2SK68A(M) FET
Qi5-6 2SA850 or 2SA777 KTA1274
Qi7-10 2SA847(G)
Qi11-14 2SA640
Qi21-24 2SK68A(L) FET
Qi25-28 2SC1345 or 2SC1328
Qi29-30 2SA899 MJE350
Qi31-32 2SC1904
Di1-4 1S2076 1N4148

Meter
Dh1-2 1N34A
Dh3-4 1N60IFT


cap series
power supply
Nichicon PW
Nichicon DK
Panasonic FM

diode
Nichicon PW
Nichicon DK
Panasonic FM

power amp
mix (general purpose + sound specific - silmic/FG/pureism)?

control
mix (general purpose + sound specific - silmic/FG/pureism)?

meter
Nichicon PW
Nichicon DK
Panasonic FM


Next question: I guess it's better not to touch certain components but how do you know what to keep and what to change?
Click to expand...
Hi, Do you use KTA1274 with TO92 like this?

https://www.yoycart.com/Product/563308340180/

Concerning STX715 wich of these two are you using (A or B)?

A..
https://www.alibaba.com/product-det...spm=a2700.7724857.normalList.9.36776afdr6xYbz

B..
https://www.alibaba.com/product-det...pm=a2700.7724857.normalList.13.36776afdr6xYbz

Thanks in advanced,
POL
 
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