Kenwood KR-9600 Upgrade, Mods and Restoration

bro4000

bro4000

New Member
Gents, I have searched the forums and I need some expert advice. I want to do all of mods/upgrades possible to my Kenwood KR-9600 but I need your recommendations on some parts due to some of them being outdated and not currently available. I plan on keeping this receiver and don’t mind spending extra money to get a more powerful, reliable and better sounding receiver. I am trying to get most of my parts from Mouser and Digikey. BD enterprises also if needed. Thank you in advance!!


· Power switch mod - adding Zettler or Omron relay, .1uf Quencharc, .1A fb fuse, fuse holder and safety cap per Echowars and others.
  • The Digikey PN 490-4217-ND for the safety cap longer available. Does anyone have another recommendation?
  • Is the .1uf Quencharc the right value in this Mod?

· Regulator board - upgrade to 25W alum case resisters and transistor upgrade
  • Mouser has a 60 ohm wirewound resistor. Should I use that instead of a 75 ohm for replacing the two original parallel 120 ohm resistors at R1,2?
  • I also want to replace the (R3)82 ohm and (R4)120 ohm resisters with alum case. Would you stay with the same values?
  • Also replacing the Qr1 with MJE15032G and Qr2 with MJE15033G. Are these the best transistors to use here?
· Need to upgrade my leaking my filter caps. It seems that over the past few years the choice for good 10,ooouf, 12,000uf and 15,000uf filter caps has become very limited. I hate the thought of having to use crappy caps for these.
  • Would it be possible to use one (great quality) 22,000uf cap per side instead of two (low quality) 12,000uf ones in parallel per side? Such as a Pioneer SX-1050. I have seen a lot of nicer caps at 22,000uf.
  • If this is not a good idea or can’t be done, what are the best 12-15K uf ones that I could use?
  • Do I need bypass caps and/or resistors across the main filter caps? If so, what values?


· Upgrading the transistors in the amps. What do you recommend as the best on each specific location below?
  • At Qe1,2 (matched) – should I use the Zetex ZT694B (noting CBE pinout) or 2SC2240BL?
  • At Qe3-5 – should I use the Zetex ZT694B or 2SC2240BL?
  • What is the best to use at Qe6?
  • What is the best to use at Qe7?
  • What is the best to use at Qe8?
I have seen the following all listed as Qe6-8 options: KSA1381, KSC3503 or KSA1220AY, KSC2682, KSC2690AY or 2SA1209, 2SC2911


· Tuner - upgrading the socket and opamp to AD823ANZ-ND. Adding two .22uf bypass caps to opamp supply pins between 4&8 and ground. Swapping zener diode dk4 on power supply with 1N5242B. Then removing caps at CB47 and CB51 and installing wire jumpers.
  • Is this the best Opamp and does this tuner mod all seem correct?
· I also noticed that my Power supply board (X00-1830-10) has gotten pretty hot at R18. It is a 390 ohm resistor. Transistor Q3 also looks like it has gotten hot on that board.
  • Any mods to fix these?

· I want to do a full recap and replace bad resistors in all of the boards but I want to do the upgrades first.

**If any of you have any more advice or suggestions for this receiver I would greatly appreciate it. I feel the KR-9600 is currently one of the best bang for the buck 160 WPC receivers right now. Thank you in advance for your help and thank you for sharing all of the info that you have on AudioKarma. Take care
 
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I'll help where I can, and I'm by no means an expert.

I have gone through 3 of these things. For Qe1-5 I have used KSC1845, HFE matching 1&2. DC offset is typically ~10mv. I think they're $6/100 so bought 200 and spent some time matching. For Qe6,7 I have used KSA1220AYS and for Qe8 KSC2690AYS. There might be better choices, but those have been fine for me.

The relay is a nice mod, but this is just as effective mucho easier as well as less dough: http://www.audiokarma.org/forums/in...orth-5-and-an-hour-or-so-of-your-time.504673/

I have used the ON Semi regulators you list and the 75 ohm aluminum cased resistor.

Your filter cap idea is interesting. Curious what others opinions are. You would have to drill the chassis for new clamps. There just aren't a lot of choices in 40mm 80v caps, so I have used snap-ins. https://www.digikey.com/products/en?vendor=0&keywords=ECE-T1KP123FA

Rk18 is a 2W resistor, so it's probably gonna get warm. Qk15 on that board (2SA809) is one of those "gotta go" transistors i have heard. KSA1220AYS works well there as well as at Qk14 which is the relay driver.

Have fun - there about a bazillion caps in these!
 
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Hello Gort69, preciate your input. If you have already done 3 of these receivers then I'd say your very familiar with the repairs and I value your opinion.
  • I will check out the triac Mod. It does look simple
  • Sounds good on the 75 ohm resistor
  • Wow thats a good price on the KSC1845!! I checked Mouser and Digikey and they are showing the KSC1845 as obsolete? Do you know how they compare performance wise to the Zetex ZT694B or 2SC2240BL? That was one drawback I saw to the 2SC2240BL, they are $1.59ea when buying 25ea or more through BD Ent. The Zetex ZT694B is $.76ea through Mouser. Not a big deal at all however if I'm buying 30ea or so to get matched pairs then it adds up. I will gladly pay more though for better quality.
  • Sounds good on the Qk14,15. Are there any other transistors or components that need to go?
  • Some of the 22K uf caps get pricey but I figure you get what you pay for. I here a few for everyone to look at but I'm sure someone out there has a better option than what I find. If the 22k's had screw in terminals that would also be convenient. I don't think I would have a problem clamping/mounting the bigger 22K caps since I would only be using two.
  • Yes there are a ton of caps in this receiver. I think I may start ordering some caps if I can figure out what types to use and where!! The Panasonic FM's and Elna Silmic II's seem popular to use. I am concerned about the Elnas 1000hr life @ 85c. I use my receivers a lot. The Panasonic FM is 3000hrs @105c. Nichicon HE is 10000hrs at 105c. There are a couple of guys that have given nice cap lists on AK for the 9600 but didn't list what type and make they had the best luck with. What have you used in your 3? Everyone else please jump in also. I will list each board, please reply with your opinions with the best caps for each.
  • Pre-amp Z08-1540-10.....?
  • Power Supply X00-1830-10.....?
  • Tuner Assy X90-1270-10.61.81.....?
  • Control Board X11-1360-10.....?
  • Relay Board X13-2400-10.....?
  • IF, MPX board X02-1100-10.....?
  • Swithches X13-2330-10.11.....?
  • Meters.....?
  • Power Amp boards X07-1480-10.....?
** I am hoping that others chime in on all of this also. Thank you!!!!
 
I'll just pass along what I learned by going through the posts just as you are doing - I hope others chime in also - I'm just regurgitating. This thread is an excellent source of info and what I referred to most often http://www.audiokarma.org/forums/index.php?threads/kr-9600-restoration-info.441957/

- I pay particular attention to posts by hopjohn, Sicman and Echowars and a few others who know their way around these things

-I should have said KSC1845FTA http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/KSC1845FTA/?qs=UMEuL5FsraDCmxWozTypUA==

- Keep an eye out for the original electrolytics that are in ORANGE jackets (either dark or light orange) - these are low leakage caps. The standard advice is to use 105 degree Nichicon UKL series in those positions. The orange caps have the suffix "BR" in the s/m parts list, but In my experience their usage isn't necessarily consistent from one unit to the next

- For 1uf 50v caps - and there are quite a few, esp on the pre-amp - use film caps. There used to be some well regarded Panasonics available, but they are NLA. These seem to be the next best bet http://www.mouser.com/ProductDetail/WIMA/MKS2B041001C00KSSD/?qs=sGAEpiMZZMv1cc3ydrPrFwgzP98AO9idwFKwdAiDxsI= These are also preferable to replace the 1uf orange caps. Some will say to use film caps for 4.7uf and lower, but size becomes an issue so I have stuck to 1uf

- There are two tantalum caps on each amp board. Wisdom is to get rid of those and replace with a single 1.5uf polypropylene film cap soldered between the two (+) holes http://www.mouser.com/ProductDetail/Panasonic/ECW-F2155JA/?qs=sGAEpiMZZMv1cc3ydrPrF0%2bjlB8SXIRuAwi0zsbAaFw=

- I have used 105 degree Panasonic FM & FC on the power supply and relay boards. Others might prefer Nichicon HE & PW

- If you're good at reading schematic (I'm not) and determining which caps are in the signal path you can put fancy caps there. I've used Elna Silmic II, Nichicon UKW, UFG (fine gold), UKZ(muse) for all positions and I can't tell a bit of difference. Just beware that Silmic II and UKZ caps are big, and fitting them can be a problem, esp on the pre-amp board which is jam-packed

- I have not messed with the tuner board out of fear of all things tuner, so no help there

- I have replaced the 24V zener diode on each amp board (De3) http://www.mouser.com/ProductDetail.../1N5252B/?qs=sGAEpiMZZMvAvBNgSS9Lqm0p7KQalEG0

- If you want a little side project, you can remove the switch body from the power switch and rotate it 180 to get brand new unused contacts. You will also have to move the end wires from each side to the unused lug. Each one I have taken apart had been ridden hard and put away wet on the AC contact. Or you can just leave it be if it's working.

- Seems worthwhile to me since this is a big project to replace both speaker relays while you're in there http://www.mouser.com/ProductDetail/Omron-Automation-and-Safety/MY4-02-DC24/?qs=eORE%2bZ%2b0Crv7hRNHqogGYw==

- My best advice is to FEAR the power amp boards and make damn sure you have it right before powering up (through a DBT of course). I don't know for a fact that a mistake here could take out a TA-200W, but I certainly didn't want to find out, and I sweated BBs each time at that first power-up

And yeah - just like Mad Magazine $25/cheap!
 
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Awesome info. Thank you for taking the time to respond. It's definitely nice to find someone that has restored these such as yourself.
  • On the triac mod, have you had any heat or other issues from the mod?
  • Also if you get a chance, please look at the two 22K caps vs four 12K caps. The ESR and ripple varies greatly but seems to be superior on the 22K's. I have read about several people that have supposedly upgraded their main caps but ended up disappointed and put their old caps back in. That's really not an option since mine are leaking
  • Anyone else have advice on all of this??
Thanks again gort!!!!!
 
The triac mod should work well in the 9600. Just be sure to use the Q6040J7TP part and follow Echowars schematic (reposted below).
Thyristor_Switch_annotated_zps6531a7db.jpg

-As far as filter caps go I'd go with these... United Chemi-Con EKMH101VRT103MB80T
-The bypass caps are optional, some like them. some don't, completely up to you.
-If you see an original orange cap use a film cap 1uf and under, over 1uf use a Nichicon UKL series cap or a film cap if it will easily fit.
-8mm diameter electrolytic caps and larger > Bump up the voltage one step at a time until you can match the original diameter. FG, RFS (Silmic II), KZ, PM and a few other audio grade series' will typically have larger diameter than most other series. Best to sort by diameter when ordering and look for the lowest voltage you can in the correct diameter and appropriate use. Use PM, PW, FR, HE, FC series for the power supply, and audio grade FG, RFS, KZ, KW for stage coupling or signal path ( if they aren't originally orange ).
 
Awesome info Hopjohn!!
  • Do you prefer the triac or relay method. The triac does look much easier, however which will be better/more reliable?
  • At Qe1-5 and Qe 6,7,8 what do you prefer to use?
  • Gort stated above that Q14 (relay) and Qk15 on the power supply board (2SA809) are those "gotta go" transistors and recommended the KSA1220AYS or 512-KSA1220AYS. Mouser is out of stock on those. Do you have a recommendation on those?
  • I am getting a big order together for Mouser and Digikey. Are there are other transistors or parts that you recommended I replace/upgrade?
  • I would like to put the best parts into this as possible
  • I have also read many of your posts, all had great information. Thank you!!!
I welcome suggestions and input on this upgrade. This forum is great!!
 
  • Use the Triac, easy, reliable.
  • I'd stick with the transistor parts from my dated resto thread. (R + L) I'd leave Qe4 & 5 alone
    • Replace Qe1,Qe2 -ZTX694B (gain matched, better gain figures than the 1845s, watch the pinouts though)
      Replace Qe3 with ZTX694B
      Replace Qe6, Qe7 with KSA1381
      Replace Qe8 x2 with KSC3503
  • KSA1220AYS is available at digikey. Qk15 2SA809 > KSA1381ESTU
  • Fairchild and On Semi parts are well regarded.
  • Understood, the 9600 is one of my favorite pieces of electronics of all time and sees frequent use.
  • Thanks, much appreciated
 
Question, so I was reading through the Triac Mod. I am ordering the Q6040J7TP (TO-218X). Do you guys have a PN for the resistor and cap?
 
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Do not just put the resistor between M1 and M2!!! It's a snubber circuit both parts are required for it to work. Some are using the snubber, some are not. For safety's sake I use it and recommend it. Either put both parts in or neither. The 100 ohm resistor at the gate (G) is not optional.

You are new here and I do not know your level of skill (just 9 posts). I'd strongly recommend leaving the triac mod to someone else if you don't understand the schematic above 100%. Dying is no fun and you seem like a nice guy. Understand building this is a bit of a challenge because so many things are being soldered to the one small part.

These are the parts I've been using:
Qty. 2 - 100 ohm Yageo 1/2 watt resisitor 603-CFR-50JR-52-100R (One for the gate and one for the snubber).
0.1uf 250v Class X2 safety cap. 667-ECQ-U2A104KL (for the snubber)
 
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Hopjohn, I am not an expert at electrician by any means however I have been in aviation and automotive maintenance since 1986. I am very familiar with automotive DC also. I am however new at restoring amplifiers and receivers. This is something that I have always desired to do but never had the time. Tribal knowledge and information through others such as yourself and other experts on audioKarma are most valuable. Yes I understand and can read diagrams and circuits however I have never used a Triac. I have dealt with tons of relays over the years. Maybe I miss-worded my question to you, if so I apologize. All that I was trying to say is that when I read the threads on the triac to get more familiar with it, there were people doing things many different ways. That is why I am asking for clarification, so I don't mess up. Thank you for the warnings on safety. I also just want to make sure that I'm using the right parts. When looking on Digikey and Mouser, there are millions of options on caps, resistors and other parts. I really appreciate all of your help on this and taking the time out of your day to respond. Hopefully one day I can pass on some useful information such as yourself. Anyway, thanks again for all of your help!!!!
 
First, welcome to AK (you said you just subscribed recently).

Keep up the fine restoration, proceed slowly, and let others lead ya home. Watching with interest.
 
@bro4000 I hate trying to dissuade anyone from doing anything with the passion you have to do this type of work, but too often I see newcomers try to tackle things they aren't ready for. The KR-9600 is one of the most difficult vintage receivers there is to work on, even Echowars will attest to that, yet this is possibly the first? such project you're inclined to do. I'd have suggested something easier to start with. Not knowing your background I'm particularly hesitant to suggest working on anything that has the potential to kill you when you seem a little confused. I pointed out the schematic specifically in post #7 because I know others have tried doing various things with this without initial success. I don't want to point to those threads to save anyone from embarrassment.

I grew up tinkering with this sort of stuff from a father who is/was well trained and yet I still don't pretend to know half of what he has already forgotten. When I worked on my KR-9600 I knew a good bit and had worked on other amplifiers. I read about all you could on this site and others before I began the project, but now 7 years on or so I'd still have done things differently with the knowledge I've gained since and my 9600 would have been better for it. The best advice I can give you is to reserve working on the most cherished of pieces until you have successfully restored a handful of other lesser vintage amps/receivers. Gain experience. This is not a slight on your abilities so don't be defensive or take exception to what I'm saying, there's more to it than just being mechanically inclined. It's simply a matter of been there, done that. Don't run the marathon before training for it.
 
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