Developing the BOM for a Kenwood KR-6160 restoration

[Hifimex]

I'll start off with the MAIN amp board:

View attachment 885133 View attachment 885134

The transistors first:

The schematic lists Qe1-Qe4 as 2SC693U(E or F), but this unit has 2SC458 transistors installed in those locations, so I'll put in KSC1845F.

Qe5,Qe6 are listed as 2SC627 in the schematic, but I can't read the label on these. The datasheet for 2SC627 is typical and boring until you reach the hFE of "360 minimum".

2SC627 NPN CBO=200 CEO=200 IC=100mA Pd=700mW fT=20MHz hFE=360

So, these will have to be high output and it took a thorough run through alltransistors to find devices that matched and Mouser to find one that was available and matched or exceeded. I'm going to try ZTX696B instead of a Darlington since I really don'[t know enough about them to select and replace them confidently.​

Qe7,Qe8 are listed on the schematic as 2SC960(I, L or M) and my unit has 2SC484Y installed there. These are complemented by the 2SA484Y in Qe9,Qe10, so a little extra care for this replacement.

2SC484Y TO-39 NPN CBO=150 CEO=110 Ueb=5V IC=1.5A Pd=800mW fT=10MHz hFE=30

KSC2073 will handle those needs well and it has a complement of KSA940, so KSC2073/KSA940 will be the ones for these.​

As stated above, Qe9,Qe10 is marked as 2SA607 on the schematic, but my unit has 2SA484Y in those positions. As stated above KSC2073/KSA940 is a complemetary pair that matches these parameters, so KSA940 is what I'll use for Qe9,Qe10.

Qe11 has a 2SC373 on the schematic, but a 2SC984 on the actual board.

2SC984 TO-1 NPN CEO=50 CBO=50 IC=500mA Pd=350mW fT=100MHz hFE=30/300

Either KSC2690A or KSC2383 should work fine in the Qe11 position.​

The strange gold-legged black-capped transistors at Qe12,Qe13 are 2SC715E

2SC715E TO-92 NPN CBO=40 Ved=5V IC=200mA Pd=125mW fT=100MHz hFE=80

View attachment 885171

It looks like KSC2383O will do fine here.​

Lastly, Qe14 is a 2SC734Y

2SC734Y TO-92 NPN CBO=70 CEO=50 Ueb=5V IC=150mA Pd=300mW fT=75MHz hFE=120

And I think KSC2383O will do fine here, too.​

There are only two sets of diodes actually on the board, so they are easy:

De1,De2 are 1N60 Germanium diodes, so I'll replace them with NOS 1N60 or 1N60P diodes

1N60 Germanium glass diode Vrrm=40V If=30mA Ifsm=150mA​

De3-De5 are strange-looking twinkie-shaped devices that the schematic calls out as SM-150-S. I couldn't find specs exactly for the SM-150-S, but I found several places where SM-150-xx were discussed and it appears these are simple 100 V 1A diodes. If anyone knows differently, please let me know. If that is correct, then they can be replaced with 1N4002, but I like the ultra fast soft recovery UF4002 better.

View attachment 885167​

The capacitors are almost all electrolytics, so the replacements are mostly easy: bump up the voltage so the replacements are operating at 60-70% rated voltage, use nothing lower than 35 V (where possible), use film caps (for zero leakage) where possible (4.7 uF or lower) or low-leakage caps (Nichicon KL series) for everything else.

• Ce1,Ce2 1 uF 50 V --> UKL2A010KDD 1 uF 100 V (Mouser doesn't even stock the 50 V version anymore) or ECQ-E1105KF3 (much larger film cap, but it has no leakage, this one is the smallest I can find, and it will fit... it'll just be ugly)
• Ce10,Ce29 47 uF 3.15 V --> UKL1V470KPDANA 47 uF 35 V
• Ce11,Ce12 100 uF 50 V--> UKL2A101KHD 100 uF 100 V
• Ce13 220 uF 25 V--> UKL1V221KPD 220 uF 35 V
• Ce15 47 uF 100 V Axial --> TVX2C470MCD 47 uF 160 V Axial
• Ce3,Ce4,Ce14 100 uF 3.15 V --> UKL1V101MPDANA 100 uF 35 V
• Ce5,Ce6 33 uF 16 V --> UKL1E330MEDANA 33 uF 25 V

I'm crazy, so I'll be replacing the one ceramic cap while I'm in there

• Ce7,Ce8 220 pF --> FK28C0G2E221J 220 pF 250 V C0G (NP0)

I'll probably replace all the resistors on this board with metal film ones, but I don't want a bunch of "hey, why would you do that" comments just because I'm OCD and have lots of spares from mistaken orders, so I'll just skip putting those in here.

There are two trimpots on this board, so I'll replace them instead of rolling the dice and having them blow a transistor or more:

VRe1,VRe2 are three-legged, single-turn 10K trimpots so they'll be replaced with 3309W-1-103​

This board leads directly to the output transistors and their resistors on the heatsink, so I'll cover those while I'm at it:

The output transistors Q1-Q4 are marked as 2SC1115 on the schematic, but 2SC898 are installed instead.

2SC1115 TO-3 NPN CBO=140 CEO=80 Ueb=5V IC=10A Pd=100W fT=10MHz hFE=30-150

MJ21194G will be a fine replacement for these output transistors.​

Power resistors at R171,R172,R271,R272 and R173,R273 may have been stressed, so they'll get updates, too.

• R171,R172,R271,R272 0.47 R 2-3 W --> CPF3R47000JNB14 0.47 R 3 W 5%
• R173,R273 4.7 R 2-3 W --> CPF34R7000FKB14 4.7 R 3 W 5%

The output in the KR-6160 is cap-coupled, so C171,C271 are huge terminal-lead caps installed up top, but I'll cover them here.

C171,C271 output-coupling caps handle the amplified signal just before it goes to the speakers, so these will need to be big (to avoid low end rolloff) and great quality (low or no leakage). Sadly, the KL series doesn't cover this much capacitance at this voltage (need 63 V minimum), so I have to look elsewhere. Nichicon makes plenty of snap-in and leaded caps in this size, so I'll choose some options that claim better audio performance but are roughly the same price as non-marketing-crap ones.

C171,C271 2200 uF 63 V --> UKW2A222MRD or LKG1K222MESAAK 2200 uF 100 V

(If Nichicon made ones that had skull tattoos on the side or little glasses of Japanese bourbon, I'd put those in there instead since they'd be "better audio quality" )​

Ok, so what of the above is just dead-wrong?

How did you get the main amp board out im in the process of doing this as well, but im not sure if the board detaches or do i have to remove all the soldering and wires fron the bottom of it

 

[Fenix479]

I’m in the process of restoring the amp board in my 6160 . But I’m thinking of using 2n3440 and 2n5416 to replace q7-q10 for some reason ksc2073 and ksa940 did not do well in my jvc vn900. Which had the same original transistors as the kr-6160. Central semiconductors work perfect.

 

[AlaskanAudio]

There are some oddball parts in there already. This should be fun....

View attachment 882509

...

De3-De5 are strange-looking twinkie-shaped devices that the schematic calls out as SM-150-S. I couldn't find specs exactly for the SM-150-S, but I found several places where SM-150-xx were discussed and it appears these are simple 100 V 1A diodes. If anyone knows differently, please let me know

De3, De4 & De5 are Schottky diodes, used (presumptively) in this application for their low noise and ultra-fast response times. So far as I can tell,
Mouser part #621-SB150-T should be a direct replacement for the SM-150-S (sans the cool protective cover/heat sink). I find it interesting that the 'recommended' replacement diode for these is a 100v unit, when the original spec is a 50v, based on the schematic. @dlucy, were there any other markings on the bottom of the diodes in question?

 

[Aethelstan]

I am working on one of these now. All speaker channels across all functions are similarly distorted. I can hear the tuner, tape monitor, etc. but they are just distorted. Based on this thread, my first inclination is to change the Q1-Q4 transistors. Service manual says they should be 2SC1115. Two of them are 2SC115, but two of them are 2SC1116A and those two appear to each have a dot of orange paint on them. Planning on replacing all four with MJ15001.

Any other ideas about what might be wrong?

 

[Fenix479]

I’m not an expert. But I would start by cleaning all the pots and push buttons. And removing the amp board and sanding the contacts With a fine piece of sand paper I had a hard time getting mine to work and the one issue I was overlooking was dirty contacts at the bottom of the amp board. And if that doesn’t fixes it I’ll start checking the power supply see what kind of voltages you have at the collectors and emitters on the output transistor. Good luck

 

[Aethelstan]

I’m not an expert. But I would start by cleaning all the pots and push buttons. And removing the amp board and sanding the contacts With a fine piece of sand paper I had a hard time getting mine to work and the one issue I was overlooking was dirty contacts at the bottom of the amp board. And if that doesn’t fixes it I’ll start checking the power supply see what kind of voltages you have at the collectors and emitters on the output transistor. Good luck

Thanks. Yeah, I gave it a good cleaning and it started working. Unfortunately, in the process of changing the Q1-Q4 transistors, I think I may have damaged one of the sockets. Not sure.

 

[Fenix479]

So thanks to this thread and help from other members of ak I was able to completely restore my 6160. I went in depth in this resto. Replacing every single electrolytic capacitor, every single transistor many many resistors, replaced the bridge rectifiers as well.
The main filter cap as well as both coupling caps were replaced with 3300uf 100v epcos capacitors and I absolutely love the sound it produces. I was able to work every board with out disordering any wires. Here are some pictures of the finished results.

 

[AlaskanAudio]

@Fenix479
Did you use the BOM in the original post, or did you come up with your own?

 

[ducati2]

Qe5,Qe6 are listed as 2SC627 in the schematic, but I can't read the label on these. The datasheet for 2SC627 is typical and boring until you reach the hFE of "360 minimum".

2SC627 NPN CBO=200 CEO=200 IC=100mA Pd=700mW fT=20MHz hFE=360

So, these will have to be high output and it took a thorough run through alltransistors to find devices that matched and Mouser to find one that was available and matched or exceeded. I'm going to try ZTX696B instead of a Darlington since I really don'[t know enough about them to select and replace them confidently.
———————-

Ok so after receiving my ztx696b replacements for Q5-6, I see they are nothing alike. Oem was metal with a metal radiator affixed, will this not matter?​

 

[bobhund]

I am currently sitting with a distortion in the main amp of an KR-6160. I'm an absolute noob in electronics. This is the sound I get:

The problem is only on the right channel and not via headphones, so it must be the main amp, mustn't it? I tried to search for the exchange transistors suggested in this thread, but I alteady fell out of luck getting them here in Europe. Most of them could be ordered from mouser. I would do that if there is no other/cheaper option. Maybe more generic transistors could also work? All help is appreciated. Thank you.

 

[Defacto]

Thanks dlucy for sharing your thought process during restore/recap.

& thanks Fenix479 for pictures from your refurbish!

 

[milo63]

I am currently sitting with a distortion in the main amp of an KR-6160. I'm an absolute noob in electronics. This is the sound I get:

The problem is only on the right channel and not via headphones, so it must be the main amp, mustn't it? I tried to search for the exchange transistors suggested in this thread, but I alteady fell out of luck getting them here in Europe. Most of them could be ordered from mouser. I would do that if there is no other/cheaper option. Maybe more generic transistors could also work? All help is appreciated. Thank you.

The headphone signal and amplifier signal are taken from the same point (download the schematic at Hifiengine.com), whatever comes out of your speakers *should* be the same as your headphones.
The 6160 has a lot of transistors on the bad list, and it's really old so the electrolytics are past their prime.

It's a varsity project, got a fixer in the area?

 

[dlucy]

It's a varsity project, got a fixer in the area?

Recapping or updating the transistors in the KR-6160 is not an easy project. The insides are chaotic, there are lots of board-to-board wiring soldered connections, and there are lots of electrolytic caps and small signal transistors to be replaced. I would not recommend this as a first or second project.

 

[jefferylhenr]

I'll start off with the MAIN amp board:

View attachment 885133 View attachment 885134

The transistors first:

The schematic lists Qe1-Qe4 as 2SC693U(E or F), but this unit has 2SC458 transistors installed in those locations, so I'll put in KSC1845F.​

​

Qe5,Qe6 are listed as 2SC627 in the schematic, but I can't read the label on these. The datasheet for 2SC627 is typical and boring until you reach the hFE of "360 minimum".​

​

2SC627 NPN CBO=200 CEO=200 IC=100mA Pd=700mW fT=20MHz hFE=360​

​

So, these will have to be high output and it took a thorough run through alltransistors to find devices that matched and Mouser to find one that was available and matched or exceeded. I'm going to try ZTX696B instead of a Darlington since I really don'[t know enough about them to select and replace them confidently.​

​

Qe7,Qe8 are listed on the schematic as 2SC960(I, L or M) and my unit has 2SC484Y installed there. These are complemented by the 2SA484Y in Qe9,Qe10, so a little extra care for this replacement.​

​

2SC484Y TO-39 NPN CBO=150 CEO=110 Ueb=5V IC=1.5A Pd=800mW fT=10MHz hFE=30​

​

KSC2073 will handle those needs well and it has a complement of KSA940, so KSC2073/KSA940 will be the ones for these.​

​

As stated above, Qe9,Qe10 is marked as 2SA607 on the schematic, but my unit has 2SA484Y in those positions. As stated above KSC2073/KSA940 is a complemetary pair that matches these parameters, so KSA940 is what I'll use for Qe9,Qe10.​

​

Qe11 has a 2SC373 on the schematic, but a 2SC984 on the actual board.​

​

2SC984 TO-1 NPN CEO=50 CBO=50 IC=500mA Pd=350mW fT=100MHz hFE=30/300​

​

Either KSC2690A or KSC2383 should work fine in the Qe11 position.​

​

The strange gold-legged black-capped transistors at Qe12,Qe13 are 2SC715E​

​

2SC715E TO-92 NPN CBO=40 Ved=5V IC=200mA Pd=125mW fT=100MHz hFE=80​

​

View attachment 885171​

​

It looks like KSC2383O will do fine here.​

​

Lastly, Qe14 is a 2SC734Y​

​

2SC734Y TO-92 NPN CBO=70 CEO=50 Ueb=5V IC=150mA Pd=300mW fT=75MHz hFE=120​

​

And I think KSC2383O will do fine here, too.​

There are only two sets of diodes actually on the board, so they are easy:

De1,De2 are 1N60 Germanium diodes, so I'll replace them with NOS 1N60 or 1N60P diodes​

​

1N60 Germanium glass diode Vrrm=40V If=30mA Ifsm=150mA​

​

De3-De5 are strange-looking twinkie-shaped devices that the schematic calls out as SM-150-S. I couldn't find specs exactly for the SM-150-S, but I found several places where SM-150-xx were discussed and it appears these are simple 100 V 1A diodes. If anyone knows differently, please let me know. If that is correct, then they can be replaced with 1N4002, but I like the ultra fast soft recovery UF4002 better.​

​

View attachment 885167​

The capacitors are almost all electrolytics, so the replacements are mostly easy: bump up the voltage so the replacements are operating at 60-70% rated voltage, use nothing lower than 35 V (where possible), use film caps (for zero leakage) where possible (4.7 uF or lower) or low-leakage caps (Nichicon KL series) for everything else.

• Ce1,Ce2 1 uF 50 V --> UKL2A010KDD 1 uF 100 V (Mouser doesn't even stock the 50 V version anymore) or ECQ-E1105KF3 (much larger film cap, but it has no leakage, this one is the smallest I can find, and it will fit... it'll just be ugly)
• Ce10,Ce29 47 uF 3.15 V --> UKL1V470KPDANA 47 uF 35 V
• Ce11,Ce12 100 uF 50 V--> UKL2A101KHD 100 uF 100 V
• Ce13 220 uF 25 V--> UKL1V221KPD 220 uF 35 V
• Ce15 47 uF 100 V Axial --> TVX2C470MCD 47 uF 160 V Axial
• Ce3,Ce4,Ce14 100 uF 3.15 V --> UKL1V101MPDANA 100 uF 35 V
• Ce5,Ce6 33 uF 16 V --> UKL1E330MEDANA 33 uF 25 V

​

I'm crazy, so I'll be replacing the one ceramic cap while I'm in there​

​

• Ce7,Ce8 220 pF --> FK28C0G2E221J 220 pF 250 V C0G (NP0)

I'll probably replace all the resistors on this board with metal film ones, but I don't want a bunch of "hey, why would you do that" comments just because I'm OCD and have lots of spares from mistaken orders, so I'll just skip putting those in here.

There are two trimpots on this board, so I'll replace them instead of rolling the dice and having them blow a transistor or more:

VRe1,VRe2 are three-legged, single-turn 10K trimpots so they'll be replaced with 3309W-1-103​

This board leads directly to the output transistors and their resistors on the heatsink, so I'll cover those while I'm at it:

The output transistors Q1-Q4 are marked as 2SC1115 on the schematic, but 2SC898 are installed instead.​

​

2SC1115 TO-3 NPN CBO=140 CEO=80 Ueb=5V IC=10A Pd=100W fT=10MHz hFE=30-150​

​

MJ21194G will be a fine replacement for these output transistors.​

​

Power resistors at R171,R172,R271,R272 and R173,R273 may have been stressed, so they'll get updates, too.​

• R171,R172,R271,R272 0.47 R 2-3 W --> CPF3R47000JNB14 0.47 R 3 W 5%
• R173,R273 4.7 R 2-3 W --> CPF34R7000FKB14 4.7 R 3 W 5%

The output in the KR-6160 is cap-coupled, so C171,C271 are huge terminal-lead caps installed up top, but I'll cover them here.

C171,C271 output-coupling caps handle the amplified signal just before it goes to the speakers, so these will need to be big (to avoid low end rolloff) and great quality (low or no leakage). Sadly, the KL series doesn't cover this much capacitance at this voltage (need 63 V minimum), so I have to look elsewhere. Nichicon makes plenty of snap-in and leaded caps in this size, so I'll choose some options that claim better audio performance but are roughly the same price as non-marketing-crap ones.​

​

C171,C271 2200 uF 63 V --> UKW2A222MRD or LKG1K222MESAAK 2200 uF 100 V​

​

(If Nichicon made ones that had skull tattoos on the side or little glasses of Japanese bourbon, I'd put those in there instead since they'd be "better audio quality" )​

Ok, so what of the above is just dead-wrong?

I know this is an old thread, but did this all work out as you outlined on the main amp board? Or did you end up changing anything?

 

[jefferylhenr]

I followed the amp board bom accept for Q5, 6 which I replaced with 2sc3503 and everything came up perfect. Sounds fantastic.

 

[tonefoto]

The restoration isn't complete, but it sounds much better now with a partial recap and replacement of some transistors. The MIC input seems to be on all the time and that circuit is definitely introducing noise. Gotta take that apart soon. Only problem is THIS is the current bedroom system, so while it is down I've got nothing to listen to except the laptop's built-in speakers. Waugh.

Know this thread is 6 yrs now, but it seemed to stop here for the KR-6160 restore. I wanted to add my experience doing one of these recently. I found the KR-6160 before restoration was pretty bloated in the bass. After a full recap and upping the power filter cap to 6800 100V and output caps to 4700 100V with 10A 600V bridge rectifier upgrade, the thing went to another level altogether. No overloaded bass, really cleaned up the sound, did the amp, pre, and tone. Tone board was a real mutha getting out of the slot they crammed it in. Broke 5 vertical standing resistors trying to shove the thing back in. All in all, it was worth the effort. Almost sounds tube like now.

 

[tonefoto]

Know this thread is 6 yrs now, but it seemed to stop here for the KR-6160 restore. I wanted to add my experience doing one of these recently. I found the KR-6160 before restoration was pretty bloated in the bass. After a full recap and upping the power filter cap to 6800 100V and output caps to 4700 100V with 10A 600V bridge rectifier upgrade, the thing went to another level altogether. No overloaded bass, really cleaned up the sound, did the amp, pre, and tone. Tone board was a real mutha getting out of the slot they crammed it in. Broke 5 vertical standing resistors trying to shove the thing back in. All in all, it was worth the effort. Almost sounds tube like now.

Does anybody else notice the tone board foil schematic image doesn't match the actual physical board on the KR-6160? At least not the one I'm working on. This is a pretty spartan service manual, so maybe I'm just missing something altogether. I had a hell of a time with this board in any case. Still experiencing problems with channel balance after the recap.

 

[mbelovar]

Hi,

some time ago i decided to buy this unit (as part of starting vintage audio journey decision I made… haha)
love the looks and feels – but sound for now not so much – so I suppose I have to get to re-caping and replacing those troublesome 2SC458´s…

I see this thread unfortunately never finished with all the Data (BOM´s etc),
Nevertheless thanks to author @dlucy on it, and all contributors, I already learned a lot

But – does anyone maybe already have finished BOM? So I don’t have to order Caps in batches as I disassemble unit?

Q: should I reconsider only replacing mentioned 2SC458´s, or maybe more (all?) transistors?

I see @tonefoto you went trough this recently – any hints & suggestions?

Many thanks! And have a god one

 

[tonefoto]

I'll start off with the MAIN amp board:

View attachment 885133 View attachment 885134

The transistors first:

The schematic lists Qe1-Qe4 as 2SC693U(E or F), but this unit has 2SC458 transistors installed in those locations, so I'll put in KSC1845F.​

​

Qe5,Qe6 are listed as 2SC627 in the schematic, but I can't read the label on these. The datasheet for 2SC627 is typical and boring until you reach the hFE of "360 minimum".​

​

2SC627 NPN CBO=200 CEO=200 IC=100mA Pd=700mW fT=20MHz hFE=360​

​

So, these will have to be high output and it took a thorough run through alltransistors to find devices that matched and Mouser to find one that was available and matched or exceeded. I'm going to try ZTX696B instead of a Darlington since I really don'[t know enough about them to select and replace them confidently.​

​

Qe7,Qe8 are listed on the schematic as 2SC960(I, L or M) and my unit has 2SC484Y installed there. These are complemented by the 2SA484Y in Qe9,Qe10, so a little extra care for this replacement.​

​

2SC484Y TO-39 NPN CBO=150 CEO=110 Ueb=5V IC=1.5A Pd=800mW fT=10MHz hFE=30​

​

KSC2073 will handle those needs well and it has a complement of KSA940, so KSC2073/KSA940 will be the ones for these.​

​

As stated above, Qe9,Qe10 is marked as 2SA607 on the schematic, but my unit has 2SA484Y in those positions. As stated above KSC2073/KSA940 is a complemetary pair that matches these parameters, so KSA940 is what I'll use for Qe9,Qe10.​

​

Qe11 has a 2SC373 on the schematic, but a 2SC984 on the actual board.​

​

2SC984 TO-1 NPN CEO=50 CBO=50 IC=500mA Pd=350mW fT=100MHz hFE=30/300​

​

Either KSC2690A or KSC2383 should work fine in the Qe11 position.​

​

The strange gold-legged black-capped transistors at Qe12,Qe13 are 2SC715E​

​

2SC715E TO-92 NPN CBO=40 Ved=5V IC=200mA Pd=125mW fT=100MHz hFE=80​

​

View attachment 885171​

​

It looks like KSC2383O will do fine here.​

​

Lastly, Qe14 is a 2SC734Y​

​

2SC734Y TO-92 NPN CBO=70 CEO=50 Ueb=5V IC=150mA Pd=300mW fT=75MHz hFE=120​

​

And I think KSC2383O will do fine here, too.​

There are only two sets of diodes actually on the board, so they are easy:

De1,De2 are 1N60 Germanium diodes, so I'll replace them with NOS 1N60 or 1N60P diodes​

​

1N60 Germanium glass diode Vrrm=40V If=30mA Ifsm=150mA​

​

De3-De5 are strange-looking twinkie-shaped devices that the schematic calls out as SM-150-S. I couldn't find specs exactly for the SM-150-S, but I found several places where SM-150-xx were discussed and it appears these are simple 100 V 1A diodes. If anyone knows differently, please let me know. If that is correct, then they can be replaced with 1N4002, but I like the ultra fast soft recovery UF4002 better.​

​

View attachment 885167​

The capacitors are almost all electrolytics, so the replacements are mostly easy: bump up the voltage so the replacements are operating at 60-70% rated voltage, use nothing lower than 35 V (where possible), use film caps (for zero leakage) where possible (4.7 uF or lower) or low-leakage caps (Nichicon KL series) for everything else.

• Ce1,Ce2 1 uF 50 V --> UKL2A010KDD 1 uF 100 V (Mouser doesn't even stock the 50 V version anymore) or ECQ-E1105KF3 (much larger film cap, but it has no leakage, this one is the smallest I can find, and it will fit... it'll just be ugly)
• Ce10,Ce29 47 uF 3.15 V --> UKL1V470KPDANA 47 uF 35 V
• Ce11,Ce12 100 uF 50 V--> UKL2A101KHD 100 uF 100 V
• Ce13 220 uF 25 V--> UKL1V221KPD 220 uF 35 V
• Ce15 47 uF 100 V Axial --> TVX2C470MCD 47 uF 160 V Axial
• Ce3,Ce4,Ce14 100 uF 3.15 V --> UKL1V101MPDANA 100 uF 35 V
• Ce5,Ce6 33 uF 16 V --> UKL1E330MEDANA 33 uF 25 V

​

I'm crazy, so I'll be replacing the one ceramic cap while I'm in there​

​

• Ce7,Ce8 220 pF --> FK28C0G2E221J 220 pF 250 V C0G (NP0)

I'll probably replace all the resistors on this board with metal film ones, but I don't want a bunch of "hey, why would you do that" comments just because I'm OCD and have lots of spares from mistaken orders, so I'll just skip putting those in here.

There are two trimpots on this board, so I'll replace them instead of rolling the dice and having them blow a transistor or more:

VRe1,VRe2 are three-legged, single-turn 10K trimpots so they'll be replaced with 3309W-1-103​

This board leads directly to the output transistors and their resistors on the heatsink, so I'll cover those while I'm at it:

The output transistors Q1-Q4 are marked as 2SC1115 on the schematic, but 2SC898 are installed instead.​

​

2SC1115 TO-3 NPN CBO=140 CEO=80 Ueb=5V IC=10A Pd=100W fT=10MHz hFE=30-150​

​

MJ21194G will be a fine replacement for these output transistors.​

​

Power resistors at R171,R172,R271,R272 and R173,R273 may have been stressed, so they'll get updates, too.​

• R171,R172,R271,R272 0.47 R 2-3 W --> CPF3R47000JNB14 0.47 R 3 W 5%
• R173,R273 4.7 R 2-3 W --> CPF34R7000FKB14 4.7 R 3 W 5%

The output in the KR-6160 is cap-coupled, so C171,C271 are huge terminal-lead caps installed up top, but I'll cover them here.

C171,C271 output-coupling caps handle the amplified signal just before it goes to the speakers, so these will need to be big (to avoid low end rolloff) and great quality (low or no leakage). Sadly, the KL series doesn't cover this much capacitance at this voltage (need 63 V minimum), so I have to look elsewhere. Nichicon makes plenty of snap-in and leaded caps in this size, so I'll choose some options that claim better audio performance but are roughly the same price as non-marketing-crap ones.​

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C171,C271 2200 uF 63 V --> UKW2A222MRD or LKG1K222MESAAK 2200 uF 100 V​

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(If Nichicon made ones that had skull tattoos on the side or little glasses of Japanese bourbon, I'd put those in there instead since they'd be "better audio quality" )​

Ok, so what of the above is just dead-wrong?

I know this is an ancient post but I'm going to add to the mystery noise on the KR-6160 after recap. I've recapped a couple of these receivers so far. I'm not a big fan of Kenwood I have to be honest. This one really sounds exceptional so I think it worthwhile to resurrect them. I too had recapped the amp, toneboard and preamp boards but still had this white noise at no volume, audible when your ear is right up to the speakers. Surprise to me, I found that giving the MIC pot a good cleaning with Deoxit cured the noise for me. YMMV.

 

[Pfrullo]

However, to reinforce the praise, this is a receiver that is hard to beat in terms of audio quality.