KA-9100 Facelift

geode

F4 Phantom Seat Jockey
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I've been eyeing this beauty since I bought it. Cosmetically it is about an 8/10. It appears to be totally unmolested. Electronically it all seems to work excepting the channel drop out once in a while. I did a quick and dirty deoxit session with it that helped. I plan on keeping this amp in my small collection. So, the restoration begins. I've already pulled the faceplate and have all the control board (X11-1410-00) apart. The plan after reading all I can find on restoring the KA-9100 is listed below.

1) Light bulb or bulbs in meter burned out. Will contact dgwojo for them.
2) Changing all electrolytics capacitors. Will use Nichicon PW and PM everywhere, except the Control board. All the orange capacitors will be replaced with Elna Silmi II and the Nichicons in otherplaces. I'm also using Wima films for the 1 uF 50V caps.
3) The 4 big filter caps will be replaced with Nichicon Gold Tune solder lug 10000 uF 63V from Michael Percy.

The Boards:

Power Supply (X00-1870-11)
1. Recap electrolytics. I am increasing the voltage to the next available higher voltage.
2. replace DZK1 YZ-140 zener with TZX14B-TAP
3. replace DK1-5 W06B diodes with 1N4005
4. Replace relay with Omron MY4-02 DC 24

Diode Board (X00-1880-11)
1. Replace 4 big filter caps with Nichicon Gold Tune
2. Replace small electrolytics with Nichicon PM or PW
3. Replace DZ9 W06B with 1N4005
4. Replace DZ10-12 1S2076 with 1N4148
5. Question? Should the transistors be changed on this board. If so,
a. QZ1,3 2SC945 replace with KSC1845
b. QZ2 2SC1212A replace with KSC2690A

Power AMP (X07-1500-11)
1. Replace all carbon resistors with carbon film 1/2W. Not replacing Metal Film.
2. Recap small electrolytics with Nichicon PM or PW
3. Transistors
a. Q1-4 2SC1775 looking for suitable replacement
b. Q5-8 2SA912 T0-92 replace with MJE350 T0-126
c. Q9,10 2SC1400 looking for suitable replacement
d. Q11,12 2SC1885 T0-92 replace with MJE340 T0-126
e. DE1,2 EQA01-24 zener replace with 1N5252B
4. replace trimmers with Bourns 3229Y 500 ohm 1/2W
5. Refresh thermal compound on TA-100W IC
6. Replace De3-6 1S2076 with 1N4148

This is all I can think of to do to this amp. You guys see any problems with the plan or is there something I should do that I haven't listed. Any problems with my substitutions. Any feedback will be greatly appreciated. I am no electronics tech but have done some light work. I have restored a Sansui G9000DB, Restored a Marantz 1060 amp, repaired Marantz 2230, 2220 receivers. Also repaired a Kenwood KR-5400. I can say this KA-9100 is a bitch to take apart and I'm sure desoldering and soldering parts is going to be a lot of fun :no: may be :D
 
On the diode board, I swap out every semiconductor. That board is such a major deal to gain access to that you don't want to have to go back in there. You'll need every bit of skill to operate on it...both to remove the old parts without damage to the board, and install the new parts correctly. This is a 'zero tolerance' board as far as mistakes go.

Replace the original 2SC945 with KSC945CYTA on this board. The KSC2690AY is good for Qz2.

On the power amp boards, Qe5, 6, 7, and 8 should be replaced with a TO-126 part, such as the KSA1220AY. Qe11, 12, replace with KSC2690AY. The originals are undersize for the job, IMHO. If you think the remaining NPN TO-92's need replacing (they are not usually a source of trouble), the KSC1845F will do.

The power switch on the 9100 is a common failure point, and a replacement is a really tough thing to locate: http://www.audiokarma.org/forums/showthread.php?t=504673
 
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On the diode board, I swap out every semiconductor. That board is such a major deal to gain access to that you don't want to have to go back in there. You'll need every bit of skill to operate on it...both to remove the old parts without damage to the board, and install the new parts correctly. This is a 'zero tolerance' board as far as mistakes go.

Replace the original 2SC945 with KSC945CYTA on this board. The KSC2690AY is good for Qz2.

On the power amp boards, Qe5, 6, 7, and 8 should be replaced with a TO-126 part, such as the KSC2690AY. Qe11, 12, replace with KSA1220AY. The originals are undersize for the job, IMHO. If you think the remaining NPN TO-92's need replacing (they are not usually a source of trouble), the KSC1845F will do.

The power switch on the 9100 is a common failure point, and a replacement is a really tough thing to locate: http://www.audiokarma.org/forums/showthread.php?t=504673

I did read the thread on using the Triac and planned on doing it too. Pretty good bang-for-the-buck considering only having to buy a Triac and resistor. I see from reading all the threads on working on this amp that it will take some time and patience. I don't think I ever saw so many components crammed onto a board like that Control Board. I made the adjustments to my Mouser parts list you suggested for the trannies. Thanks again for sharing your knowledge with me on one of my projects.
 
Yes....Good Luck with the restore. I had picked one up 1yr+ ago. Was going to Recap this...As said...It's a PITA on getting to the caps...I wound up putting this in a box as it's not worth my time.

I also recapped a KA-8100....So nice to work on.
 
Yes....Good Luck with the restore. I had picked one up 1yr+ ago. Was going to Recap this...As said...It's a PITA on getting to the caps...I wound up putting this in a box as it's not worth my time.

I also recapped a KA-8100....So nice to work on.

I can see that it will be a challenge for sure. I got my parts in today, so I should be ready to start probably Friday. I took a few notes and lots of pictures. I can't hardly wait to finish it. I want to do a head-to-head with my Marantz PM8004. Should be interesting. Put it in a box, huh :scratch2:
 
Got the parts yesterday. I can't believe how fast Mouser got the stuff to me. Anyway, I bought some film caps to replace the ceramic death cap and am wondering if this cap is appropriate and/or better than the old ceramic. The cap I'm referring to is soldered onto the power switch. Is this one okay
http://industrial.panasonic.com/www-data/pdf/ABD0000/ABD0000CE29.pdf

Thanks.

Also noted that the value for this cap in the service manual is .01uF and I bought .1uF...is this gonna matter
 
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Sorry you've already gotten your order. The orange caps are Low Leak caps and should be replaced by Nichicon UKL or film if the size fits. Hope the project goes well.
 
Sorry you've already gotten your order. The orange caps are Low Leak caps and should be replaced by Nichicon UKL or film if the size fits. Hope the project goes well.

I have used the KL series to replace the orange caps on some of my past projects. I have also read the Pioneer Tuning Forks concerning the caps and the many threads of the KL versus the Audio Grade caps. Seems to be a split on this one. I simply can't tell the difference between using the KL or audio grade caps to replace the orange ones. I think the audio caps are more than sufficient. They are more expensive than the KL caps, though, so there is that. Thanks for the feedback. I think the project will go well, unless of course I screw something up :D
 
I have the control and preamp boards finished. Now I'm focusing on the thyristor mod to the power switch. I bought the isolated Triac and plan on drilling a small hole to mount it to the chassis for heatsinking. I'm just wondering if 16 AWG TFFN stranded wire is suitable for the modification. I have some on hand.
 
The current to-and-from the original power switch (MT2 through the switch and through the 100 ohm resistor and back to the gate) is tiny (100mA or therabouts). 28ga wire is fine for that. The original primary wire running to the switch ought to be usable by simply rerouting it to the MT1 and MT2 of the thyristor.

index.php
 
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The current to-and-from the original power switch (MT2 through the switch and through the 100 ohm resistor and back to the gate) is tiny (100mA or therabouts). 28ga wire is fine for that. The original primary wire running to the switch ought to be usable by simply rerouting it to the MT1 and MT2 of the thyristor.
attachment.php

Thanks EW for shedding some light on this, but I'm confused. I thought I had it but, no. So, on your drawing the pin "Hot" is the middle pin on the power switch and its wire is to be removed and soldered to the Triac MT2. Then run a new 28 awg wire from the middle pin "Hot" to where? The triac Gate is connected to the bottom power switch pin by the 100 ohm resistor. And the original wire "Load" that was connected on the bottom pin of the power switch is connected to the M1 of the triac. Hate to sound like a dummy, but that there's the facts :D

I keep staring at this drawing and it seems like the original "Hot" wire is desoldered from the middle pin of the power switch and soldered to the leg of M2. And the new 28 awg wire is soldered to the middle pin of the power switch and then soldered to the leg of M2 also. So M2 has two wires soldered to it. Just a guess of course.
 
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:lurk: Can't wait to see the results. I have one sitting in my closet....just waiting for some spare time.
 
The big, heavy, high-current wires will go to MT1 and MT2. It is not critical which wire goes to which, the thyristor will work regardless.

BUT, the power switch needs to short MT2 and the Gate through a 100 ohm resistor. The wires running from the thyristor to the power switch do not need to be large, as the current here is very low.

Note that without the snubber circuit from MT1 to MT2, it's possible for AC line garbage noise to activate the thyristor.
 
The big, heavy, high-current wires will go to MT1 and MT2. It is not critical which wire goes to which, the thyristor will work regardless.

BUT, the power switch needs to short MT2 and the Gate through a 100 ohm resistor. The wires running from the thyristor to the power switch do not need to be large, as the current here is very low.

Note that without the snubber circuit from MT1 to MT2, it's possible for AC line garbage noise to activate the thyristor.

Thanks again EW. I think it's clear now. I also bought .1uF 250V filmcap/safety cap X2/Y2 for the snubber and 100ohm 1 watt wirewound resistors. I put the front back together last night after recapping the control/preamp and meter boards. Also deoxited and falderlubed the piss out of the controls. D5 and then D5 Gold on everything except the volume pot which got D5 first then faderlube. I will put in the new light bulbs when I do the Diode board. After the Thyristor is installed I'm planning on doing the Power Supply next with a little more D5 and Gold for the separate switch on the rear panel. Lots of screws on this beast:yes:
 
I finally got the Thyristor installed on the power switch. I built a DBT to be on the safe side. I don't have a 100W bulb. Home Depot and walmart both don't carry them anymore. Unbelieveable. I bought a 72W Halogen. On power up the Bulb turns on bright then pretty quickly dims down. But it never goes out completely. I replaced it with a 60W incandescent bulb and the same thing. I've used a DBT before and it seems the bulb turns on bright then goes out completely. At least that has been my experience with at least 5 pieces of audio gear. So, am I looking at a problem now or do I really need a 100 W bulb.
 
Nope you should be good. I don't know if you have a Menards around but I picked up a bunch of 100w incandescents there recently.
 
Here is one thing I noticed about the Thyristor Mod. EW said it gets warm and so some heatsinking is in order. At first I was going to drill a hole in a spot on the chassis and mount it there. But after looking closer, I noticed that the Heatsink has two Ears attached to it. And they are conveniently located right where the Thyristor can be mounted. The ear is already drilled and tapped for a screw. It just so happens the screws used on the bottom cover (and probably others) fits this hole nicely. So, that is where I mounted my Thyristor. Very easy and convenient and should provide good heatsinking. See attached
 

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