Got a Kenwood KR-9600!! Though, needs a few things......

Hey everyone, about a week ago i was on craigslist and up pops up an ad for a KR-9600 for a pretty good price. Been hunting for one for a while and finally found a chance for one for a good price. Went to the guys house and found out he's actually a member on Ak but not a poster. The thing is that he owns EVERY or has had almost EVERY monster receiver from the 70s. Currently he has TWO Rotel RX-1603s, two Concept 16.5s, a G22000 and 9000, Hitachi SR-2004 and god knows what else. He's had all the bit SX series receivers too. He even showed me the garage and i walk in and its loaded with stereo gear haha.

Anyways, go there, he shows me and lets me listen to the KR-9600. Few cosmetic blemishes here and there but nothing serious. Sounds GREAT! Pick it up this past sunday and brought it home. Well I went through it like I usually do and did a DC-offset check and found out it has 134mV on the right and 55mV on the left. The KR-9600 has no offset/bias adjustment so from what Glenn (Echowars) said is to change the NPN input differential pairs along with the caps on those boards.

I also have another few questions if y'all could answer them for me:

1. How in the world do i get those damn toggle switch covers off so i can get the face off? They are stuck on...
2. How the hell do you get to the push-button switches to clean them? like the filter and FM muting button?
2. I keep on hearing of mods that can be done to the tuner section and also installing a soft start relay to prevent in-rush current load on the power-switch?
3. When i go about to changing the NPN input differential pairs on the power amp boards, how do I go about discharging the big power caps so I don't short out the IC's?

So heres a list of things i've done to the 9600:
Cleaned all the crap out that collected from when it was with the previous owner.
Cleaned the pots (most except the push-buttons) and checked DC offset.

Things that need to be done (and whatever else you all suggest when i start tackling this project)

1. Change the NPN input differential pairs. Glenn, you said change Qe1, Qe2, and Qe3 with the the Zetex ZTX694B? But you mentioned you must be careful, as the Zetex parts are center-base and the originals are center-collector? Also something about "matched-pairs" for the Zetex ZTX694B?

http://www.mouser.com/ProductDetail...=sGAEpiMZZMsTKkj12KWLXttIJOGzFdY2gLkSr7SMGKI=

2. Change also Qe6 and Qe7 with with new KSA1381 and Qe8 with a KSC3503 (or 2SC3503). I think its these links?

http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxNmD2KTdTUa8=

http://www.mouser.com/ProductDetail...GAEpiMZZMsTKkj12KWLXuW5oDYpP%2bzxnFgdckrhqM4=

http://www.mouser.com/ProductDetail...=sGAEpiMZZMsTKkj12KWLXuh07PZXrEQw6Pgdt0KlMww=

3. Change the caps on the board and thermal compound on the Power-Pack IC's. Which thermal compound should i buy or caps too?

Anything else i miss? Since i'm already going to be taking the receiver down that far to do the power amp boards, should i go ahead and change the big power caps too? Or hell go ahead and recap the whole darn receiver? If anyone has a cap-list to share that would be great!!

Sorry everyone for all the questions, just wanna get this right the first go around without blowing anything up you kno.

Ohh, forgot, pictures!!!





Here's a picture of the 9600 with the little baby receiver of that series of KR receivers, the KR-2090.


Cleaning



Can't get those darn toggle covers off...

I have a spoon with a padded backside that I use to catch the lip of those toggle switch covers. Spoon on one side of the switch, finger on the other side to help keep the switch straight.

Ahhh okay, I will go ahead and try that now with some tissue or something.

Is everything on parts for the NPN input differential pairs correct? Anything i leave out or should do also? How many of those Zetex's do i have to get to get a matched pair or really how do i tell if I have a matched pair? Sorry if i'm asking dumb questions....

lha1992 said:

Ahhh okay, I will go ahead and try that now with some tissue or something.

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Try a couple or three layers of duct tape to protect the face...just cover the back of the spoon.

Is everything on parts for the NPN input differential pairs correct? Anything i leave out or should do also? How many of those Zetex's do i have to get to get a matched pair or really how do i tell if I have a matched pair? Sorry if i'm asking dumb questions....

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You appear to have it right, I think.

This is the thermal compound I use. They also sell a 2oz jar.

The number of devices you need to match two pairs depends on how close you want to match them. If you shoot for 5%, then I'd say you might need two dozen devices to get two pairs. Don't ignore my warning about the lead orientation.

EchoWars said:

Try a couple or three layers of duct tape to protect the face...just cover the back of the spoon.You appear to have it right, I think.

This is the thermal compound I use. They also sell a 2oz jar.

The number of devices you need to match two pairs depends on how close you want to match them. If you shoot for 5%, then I'd say you might need two dozen devices to get two pairs. Don't ignore my warning about the lead orientation.

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Okay, i'll try duct tape then to protect the face since it won't tear like tissue.

Now for the warning on the lead orientation, are you talking about how the Zetex parts are center-base and the originals are center-collector?

Also, when you say on how close you want the devices to match do you mean in resistance or in how they look? I told you, i'm new to alot of this stuff. I just need to figure out the matching of the parts is all and i'm good with breaking the 9600 down haha.

Ohh, for caps, what caps do you prefer?

The only parameter we're interested in with the transistors is gain (beta, Hfe). You will need a meter capable of measuring this.

I say be careful because mistakes can be costly working with this amp, using an output module. The board is poorly marked for Collector, Base, and Emitter. Get a good copy of the manual and follow it carefully for orientation.

Caps: Panny FM & FC, and Nichicon PW & HE. I also get rid of the back-to-back tantalums at the amp input and replace with a single 1.5µf film cap, usually a Panasonic ECWF(A) or (B). Digikey #P13746-ND will work well for an input cap.

EchoWars said:

The only parameter we're interested in with the transistors is gain (beta, Hfe). You will need a meter capable of measuring this.

I say be careful because mistakes can be costly working with this amp, using an output module. The board is poorly marked for Collector, Base, and Emitter. Get a good copy of the manual and follow it carefully for orientation.

Caps: Panny FM & FC, and Nichicon PW & HE. I also get rid of the back-to-back tantalums at the amp input and replace with a single 1.5µf film cap, usually a Panasonic ECWF(A) or (B). Digikey #P13746-ND will work well for an input cap.

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So i checked my meter to see if it is capable of measuring Hfe and beta, well from the looks of it if can measure Hfe but IDK about beta. It has diode measurement so. It might have beta too but IDK.

For the caps, what do you think of Nichicon Gold Tunes?

Also, does this look good right here? I believe this is the power supply board-B correct? It gets really hot which i hear is normal for the 9600 but to be blackening like that is that normal.....



Heres more pictures as it was being finished cleaning. I did get those darn toggle caps off! Used car polish on the face and came out GREAT!





Here it is powered up checking to see if it needs more deoxit or not before i button it back up.





All buttoned back up!

lha1992 said:

For the caps, what do you think of Nichicon Gold Tunes?

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Your project, your call.

Also, does this look good right here? I believe this is the power supply board-B correct? It gets really hot which i hear is normal for the 9600 but to be blackening like that is that normal.....

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I replace the two 120Ω resistors with a single 25W 75Ω aluminum resistor mounted on the 'wall' right behind the board. Cools things off considerably. Fresh heatsink grease on those two transistors is a good thing as well.

EchoWars said:

Your project, your call.I replace the two 120Ω resistors with a single 25W 75Ω aluminum resistor mounted on the 'wall' right behind the board. Cools things off considerably. Fresh heatsink grease on those two transistors is a good thing as well.

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So for the caps it just depends on how much I want to pay literally right.

And your talking about the resistors screwed onto those 2 heatsinks on that board?

But as for the blackening its alright for now?

BTW, as we talk i've been building cap list for the 9600. If you have any other suggestions I should do as I recap this thing please lemme know.... Haha I'm asking wayyy to many questions lol :yes:

The only Nichicon Gold Tune caps I'm aware of are large power supply caps. There are no Nichicon GT caps in a 40mm diameter with a voltage rating of 80V or better that might be used as power supply caps in the 9600. I've been using CDE #382LX123M100N082 (12,000µf 100V) to replace the originals in 9600's. Digikey #338-2114-ND.

The devices screwed to the heatsinks are transistors. The cylindrical things soldered to the PC board are resistors. Are you up to this?

EchoWars said:

The only Nichicon Gold Tune caps I'm aware of are large power supply caps. There are no Nichicon GT caps in a 40mm diameter with a voltage rating of 80V or better that might be used as power supply caps in the 9600. I've been using CDE #382LX123M100N082 (12,000µf 100V) to replace the originals in 9600's. Digikey #338-2114-ND.

The devices screwed to the heatsinks are transistors. The cylindrical things soldered to the PC board are resistors. Are you up to this?

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Ahhh okay I see now. I will just go with the Nichicon PW & HE caps. For the power caps could I go up in filtering to like 15,000uF? I do know that if I do I would have to devise a soft start relay of some sort since the 9600 does not have one?

And yea, i just realized what I said about transistors vs. resistors. I know the difference....now haha. Or I did but was confused. I'm up to doing this! I have my dad who has a computer and aerospace engineering degree to help me if i need help. And if I need more help I will get in contact with you or some other member who knows about the 9600.

That's a beauty. Nice work on the cleanup.

I'd stick with the filters that EW recommended. The 9600 has plenty of filter capacitance. If you do have to tweak filter values, it's good to stay within 10% of the original value.

I think I have some ZTX694B from a previous project. I could match up a couple pairs for you, might have to remind me though.

Jailtime said:

That's a beauty. Nice work on the cleanup.

I'd stick with the filters that EW recommended. The 9600 has plenty of filter capacitance. If you do have to tweak filter values, it's good to stay within 10% of the original value.

I think I have some ZTX694B from a previous project. I could match up a couple pairs for you, might have to remind me though.

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Hey thanks Kyle!! It took a WHILE to clean this beast! The guy I bought it from has SOOO many rare and unique receivers its crazy. So this one didn't get much use really.

I think I will stick with the filter values Glenn said because for one that will hold off for me not having to make a soft start relay since the 9600 doesn't have one.

And you have some ZTX694B??? Cool!! If you could I would be soooooo appreciative because I don't have a multi-meter capable of beta reading i believe. I'll send you a PM.

So, I've already got a cap list going for the 9600 and starting to order caps. Now should I be changing any of the Mylar/Ceramic/film caps? Or only the electrolytics?

And also, I said I was going to order Nichicon PW and HE caps but what type of caps should I use in the power supply? Audio caps still? Or caps that have high ripple current? What about ESR ratings?? Also, temp wise for the caps, -40-105degree celsius or -55-105degree? Are their any other REALLY good caps i could try out in this thing too?

lha1992 said:

So, I've already got a cap list going for the 9600 and starting to order caps. Now should I be changing any of the Mylar/Ceramic/film caps? Or only the electrolytics?

Click to expand...

Just the electro's will keep you plenty busy.

And also, I said I was going to order Nichicon PW and HE caps but what type of caps should I use in the power supply? Audio caps still? Or caps that have high ripple current? What about ESR ratings?? Also, temp wise for the caps, -40-105degree celsius or -55-105degree? Are their any other REALLY good caps i could try out in this thing too?

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Nichicon PW and HE for about 90% of everything. Elna Silmic II for signal path duties, and small (1µf) caps should be replaced with stacked film caps.

So i checked my meter to see if it is capable of measuring Hfe and beta, well from the looks of it if can measure Hfe but IDK about beta

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Hfe and βeta are the same thing.A measurement of foward current gain.

Caps Caps Caps...This is what I have been doing after my 1st Recap of Pioneer SX-1050 (Nichicon PW, KL). From my equiment list all Recapped(Nichicon FG,KZ,KG and Elna Silmic II) but not the Luxman R-117.

I completed a Sony STR-6800SD and used Elna Silmic II and 1uf< stacked film caps 2 weeks ago. The Main cap I did not touch..These are 2 Caps in one case.

The STR-6800SD is no "Monster" as to the Kenwood but what I hear...the Elna Silmic II are " Night/Day" to the Nichicon PW. I no I no Ripple Rush, 3000-5000hrs vs 1000hrs MBF and so on...So I will need to recap the Sony in 15yrs...

The Pioneer SX-1050 is only + 125watt I recapped using Nichicon PW, KL(Thank You Mark)..This was fully recapped I did last year..search for thread. Sound is strong...but does not compare in using Audio caps like Nichicon FG,KZ and Elna Silmic II (Sound Stage, Lows thur Highs very detailed)

What I will do mid-year is use Elna Silmic II in the Power Areas in the SX-1050. I really do not use the SX-1050 anymore so this will be a nice test how well the Elna Silmic II, Nichicon FG,KZ with hold up.

I heartily encourage the replacement of the opamp on the FM tuner board. I was quite impressed with this upgrade.
Here's EW's post on the matter:
http://audiokarma.org/forums/showthread.php?s=&threadid=5974

Well, I kinda exaggerated how bad it was (that was nine years ago...). The biggest help for sound quality was using an opamp with low enough offset that I could replace the output caps on the opamp with a straight wire.

Anyway, last 9600 got an Analog Devices AD823 for the audio opamp on the FM. Offset was less than 1mV on both channels and it sounded great...even better once the caps were removed and jumpered.

One thing that may help keep offset low is to tweak the supply voltages to it. They are supposed to be +13.2/-13.5, but are always off. The zeners (Dk2 & 4) are supposed to be 14V 500mW, but Dk4 usually has to be changed to a 13V or a 12V zener for the voltages to be reasonably close (I like to see opamp split supplies to be within about 500mV, absolute value, and I can usually get it). In other words, I don't want to see +13V/-14.5V, but I'd settle for +13V/-13.5V.

EchoWars said:

I replace the two 120Ω resistors with a single 25W 75Ω aluminum resistor mounted on the 'wall' right behind the board. Cools things off considerably. Fresh heatsink grease on those two transistors is a good thing as well.

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Did you replace both Rr1 and Rr2's 120Ω 2W resistors with 25W 75Ω aluminum resitors?

And just leave Rr3 and Rr4 alone right?

Also, Jailtime was really kind enough to send me some extra matched pairs of the Zetex ZTX694B for Qe1 and Qe2 for the power amp boards. I'm thinking of changing Qe3 also with the Zetex but is that really needed?

I'll be posting up a cap list of what i got so all of you can check and see if its right. Whats the pecking order of the Nichicon FG, KZ, PW, HE? Getting kinda confused and been searching the forums so.