Kenwood KA-9100 popping

I've seen the popping issue on several 9100s. Every time, it was the transistors that I mentioned. Though you are right to suspect something that is common to both channels.
 
Thanks guys. I'm going to take your advice and get after the board. That seems like a good place to at least start. Also, I've already looked at hopjohn's post, which is great. So I'm going to follow his parts recommendations and get to work.
 
I presume that the best way to go about working on the driver board is to leave it connected, but pulled out far enough to change components. Does anyone recommend completely removing the board from the chassis? All those wrapped wire to lug connections aren't something I really want to tackle, unless you guys think that's the best way. If so, what's the best way to de-connect those wraps?
 
There is no need to mess with a single wire wrap on the ka-9100.

Driver board (amp board?) - Do one side at a time. Remove the two blanking covers on the heatsink and remove the 2 screws that they hide - these attach the output module to the heatsink. Remove the 2 screws that hold the amp board to the chassis. Check to make sure the thermal coumpound hasn't glued the module to the heatsink. Then remove the heatsink from the chassis. Easiest to have the unit standing on edge to do this. Look at the bottom side - you might need to cut a ziptie or two to get slack in the wiring - I forget. There is ample room to get to everything you need.

The 2 power amps and the power supply are fairly simple to access and work on on - the rest are not
 
Last edited:
No, I'm talking about the driver amp board. I'm not sure it will pull out far enough to allow changing out components without getting it free of the chassis.

upload_2018-3-31_17-2-34.png
 
The power supply board solder side is accessed by tilting the rear panel down. Prop the amp up on a couple thick books or similar. I think there are 6 or 8 screws or thereabout holding it in place. Then a few screws that attach the board support brackets. I don't remember whether or not the metal shield for the RCAs need to come out or not - if so, 3 screws on the rear panel attach it.

P1011031.JPG
 
Last edited:
Yeah, I know. The photo I attached is just from the underside with all the wrapped wire connections. But if that back will release like you described, as I'm sure it will, that's all I needed to know. Thanks. Now back to work. But I guess there's no hurry, in that I should just go ahead and put in my Mouser order. Hopjohn's post makes that pretty straight forward.
 
scottonnob said:
Okay, I pulled this unit off of my 'Later' shelf to see about rebuilding it.......

I'm really stumped. Can any of you suggest some sort of diagnostic approach, so as to finally locate the problems? I really don't know where to start.

........
Click to expand...

The logical place to start was offered in Echowar's post. If the problem occurs when running one section, then you have eliminated the other section and narrowed down the search.
 
Last edited:
I eliminated the pre-amp part of the unit already. And the problem is in both channels. So I'm going to go ahead and rebuild the power supply board.
 
Okay, before I place my Mouser order, I need to ask if the board in my unit is different than the one hopjohn references in his/your KA-9100 Build Sheet. My board is XO-1870-00, rather than XO-1870-11. Is there a substantive difference, in relation to ordering parts, that anyone knows of?
 
Looking at the picture in hopjohn's thread, his board is also -00. You should be fine. If in doubt order based on what's installed on yours. I don't remember what mine are. The s/m lists -11. Could be an error or a production change.
 
Another Ka 9100 owner.. and I have gone into the unit to do some light repair. Best advice, label everything as you advance the diagnostic, there are loads of boards crowded into the unit.

My issue was the preamp stage and I am still seeking the right replace components, and will use some of the advice given this post.

For the earlier part of the year, I used the amp power side, and it had no issues and sounded great. Finally I got ahold of a Kenwood Model 9508 to temporarily put in my house loop. It works great though not as powerful.

Now the 9100 sits idle waiting for me to take the next repair steps.
 
47uf 50V KZ 10mm back-ordered at Mouser. Amazon has Elna 47uF 50v Bipolar Non-polar Radial Electrolytic Capacitor BP NP RBP2. Are these a reasonable substitute?
 
Got everything desoldered and removed. Then I spent twice as much time cleaning the damn board. The back was fully and thickly coated with whatever it is they put on the connections. I suppose it could be flux, but I doubt it. More likely some kind of protective preservative. Could be wrong. Then the 'Glue From Another Planet'. The stuff they use to secure the big caps is like nothing I've seen before. Lacquer thinner wouldn't touch it. Only acetone or Goo Off worked. And even then, it took me forever working with big Q-tips. Only that glue and the cockroaches will remain after the impending apocalypse. Tomorrow I'll populate the board with all the new components and take the amp for a ride.

upload_2018-4-6_19-27-52.png

upload_2018-4-6_19-28-19.png

upload_2018-4-6_19-29-27.png

upload_2018-4-6_19-29-54.png
 
One more question. I'm a bit suspicious of all those wrapped wire connections at the bottom of the board. It's just a lot of moving around for the wires. Do any of you recommend flowing some solder into the wrap as a precaution? I looked with a magnifying glass at all the connection points and everything appeared to be in order. But I still don't trust them.
 
Nice work. The nasty stuff on the solder side is flux. The wire wraps themselves should be fine. Much more likely is that a solder joint gets cracked or broken where the pins solder to the board, so I'd inspect those.
 
Yeah, good point on the wrapped connections. I'm actually going to re-flow a few other connections on the board. A couple of them look a bit suspicious. They are pretty thinned out and it's easy preventive insurance. So I'll also look closely at those bottom, major connections.
 
I'm assuming the WIMA 4.7, 50v cap is nonpolarized. The legs are the same length, but the board suggests that what came out of there was polarized. Don't want to make a silly error.
 
You must log in or register to reply here.

Similar threads

R
handles for kenwood ka-9100?
Replies
9
Views
2K
rhinofly
R
radioactive
kenwood ka 9100 on the bay
Replies
18
Views
1K
TWantiques
TWantiques
lha1992
Need help with my Kenwood Ka-9100 amp
Replies
17
Views
2K
lha1992
lha1992
B
Kenwood KA-9100 Voltage Conversion
Replies
2
Views
483
black220
B
Silente
Kenwood KA-9100
Replies
18
Views
861
mbz
M
Back
Top Bottom