Project: Kenwood KR-8050

[Super Noob]

Yet another project for rebuild. The candidate is a KR-8050. Have rebuilt a couple of the KR-8010s in the last year or two. The KR-8050 is touch newer. It was found with a busted bass potentiometer, dirty, and knobs surfaces less than perfect.

Saw one of the years before and when this came available could not pass on the project. It is rated at 120 WPC.

Here is the list of replacements caps and the last page include transistors references that I changed. Hope you enjoy the upcoming posts. My hopes is that my journey will help someone or inspire someone to rebuild this set.

https://drive.google.com/open?id=1AZSy4BQUTGm87z0pOjih-D2gPhE3Hyk5

 

[Super Noob]

Tone Amp (X11-1590-10 B/7) C17 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C18 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C19 - Original 10uF 25v (LL) / Now 10uF 35v (NICH UKL1V100MDDANA)
C20 - Original 10uF 25v (LL) / Now 10uF 35v (NICH UKL1V100MDDANA)
C29 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C30 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C31 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C32 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C37 - Original 10uF 50v (LL) was 1uF 50v (per print) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C38 - Original 10uF 50v (LL) was 1uF 50v (per print) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C39 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C40 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C41 - Original .1uF 35v / Now .1uF 63v (WIMA MKP2C031001F00JS)
C42 - Original .1uF 35v / Now .1uF 63v (WIMA MKP2C031001F00JS)
C45 - Original 220uF 16v / Now 220uF 25v (NICH UKA1E221MPD1TD)
C46 - Original 220uF 16v / Now 220uF 25v (NICH UKA1E221MPD1TD)

Before:

After:

 

[Super Noob]

Tone Amp (X11-1590-10 A/7)
C1 - Original 47uF 16v / Now 47uF 25v (NICH UKA1E470MDD)
C2 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C3 - Original 100uF 50v / Now 100uF 50v (PANA EEU-FM1H101)
C4 - Original 47uF 16v / Now 47uF 25v (NICH UKA1E470MDD)
C5 - Original 100uF 16v / Now 100uF 25v (PANA EEU-FM1E101)
C6 - Original 47uF 16v / Now 47uF 25v (NICH UKA1E470MDD)
C7 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C8 - Original 100uF 35v / Now 100uF 50v (PANA EEU-FM1H101)
C10 – Original 1000uf 16v / Now 1000uf 35v (NICH UPW1V102MHD)

Before:

After:

 

[Super Noob]

POWER AMP (X07-1740-10 A/5)
C14 - Original .1uF 50v (Actual .33 uf 50v LL) / Now .33uF 100v (WIMA MKS2D033301E00JSSD)
C31 - Original 470uF 16v / Now 470uF 35v (NICH UPW1V471MPD1TD)
C32 - Original 470uF 16v / Now 470uF 35v (NICH UPW1V471MPD1TD)
C33 - Original 470uF 16v / Now 470uF 35v (NICH UPW1V471MPD1TD)
C34 - Original 470uF 16v / Now 470uF 35v (NICH UPW1V471MPD1TD)
C56 – Original 100uF 16v (BP) / Now 100uF 25v (MUSE NICH UES1E101MPM )
C57 - Original 47uF 16v (LL) / Now 47uF 25v (NICH UKL1E470KED)
C61 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C62 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C63 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C64 - Original 100uF 10v / Now 100uF 25v (PANA EEU-FM1E101)
C69 (1) - Original 10,000uF 71v / Now 15,000 uF 80v (CHEMICON ESMH800VQT153MB63T)
C69 (2) - Original 10,000uF 71v / Now 15,000 uF 80v (CHEMICON ESMH800VQT153MB63T)
RL1 – Original NEC MS4U (24VDC) / Now Omron MY4-02 (24VDC)

Went back in and replaced all the transistors and many of the diodes.

Outputs were pulled at this time... cleaned and re-greased with Wakefield 120.

Large Filter Caps = Pulled Off Old Solder Tabs and Mech Attached and Solder On New Filters

Added My Typical 2.2 uF Panasonic Stacked Films.

Not The Most Fun Board to Work On - After Pics

Every Transistor Was Changed On This Board:

 

[Super Noob]

POWER AMP (X07-1740-10 B/5)
C3 - Original 100uF 10v / Now 100uF 25v (PANA EEU-FM1E101)
C4 - Original 100uF 10v / Now 100uF 25v (PANA EEU-FM1E101)
C5 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C6 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C13 - Original .1uF (mylar) / Now .1uF 630v (Panasonic ECW-FA2J104J)
C14 - Original .33uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C15 - Original 1uF 100v / Now 1uF 100v (WIMA MKS4D041002F00JS)
C16 - Original 1uF 100v / Now 1uF 100v (WIMA MKS4D041002F00JS)
C19 - Original 100uF 16v / Now 100uF 25v (PANA EEU-FM1E101)
C20 - Original 100uF 16v / Now 100uF 25v (PANA EEU-FM1E101)
VR1/VR2 (Offset) – 100 Ohm VR / Now 100 Ohm VR (Bourns 3386H-1-101 LF) Single Turn – Sealed
VR3/VR4 (Bias) – 100 Ohm VR / Now 100 Ohm VR (Bourns PV36P101C01B00) Multi-Turn – Sealed

Before:

After:

Elected to change all the transistors and zeners on this board... all transistors numbers are on pdf document on link on first post. (last page).

 

[Super Noob]

PRE AMP (X08-1740-10 A/6)
C9 - Original 47uF 16v / Now 47uF 25v (NICH UKL1E470KED)
C10 - Original 47uF 16v / Now 47uF 25v (NICH UKL1E470KED)
C11 - Original 22uf / 25v / Now 22uF 35v (NICH UKA1V220MDD)
C12 - Original 22uf / 25v / Now 22uF 35v (NICH UKA1V220MDD)
C13 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C14 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C17 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C21 - Original 10uF 25v (found 22uf / 16v) per schematic/ Now 22uF 25v (NICH UKL1E220KDDANA)
C22 - Original 10uF 25v (LL) / Now 10uF 35v (NICH UKL1V100MDDANA)
C23 - Original 330uF 35v / Now 330uF 50v (NICH UKA1H331MPD)
C24 - Original 330uF 35v / Now 330uF 50v (NICH UKA1H331MPD)
C25 - Original 100uF 35v / Now 100uF 50v (PANA EEU-FM1H101)
C26 - Original 100uF 35v / Now 100uF 50v (PANA EEU-FM1H101)
C27 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C28 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C29 - Original 1uF 50v (LL) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C33 - Original 47uF 25v / Now 47uF 35v (NICH UKL1V470KPDANA)
C34 - Original 47uF 10v (found 22uf / 35v) per schematic / Now 22uF 50v (NICH UKA1H220MDD1TD)

Before:

After:

 

[Super Noob]

TUNER (X05-1700)
C8 - Original 1uF 50v (NP) / Now 1uF 63v (WIMA MKS2C041001FJC00)
C10 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C15 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C22 - Original 220uF 6.3v / Now 220uF 16v (NICH UKA1C221MED1TD)
C23 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C27 - Original 220uF 16v / Now 220uF 25v (NICH UKA1E221MPD)
C34 - Original 4.7uF 25v / Now 4.7uF 35v (NICH UKT1V4R7MDD)
C35 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C36 - Original 100uF 10v / Now 100uF 25v (PANA EEU-FM1E101)
C41 - Original 100uF 16v / Now 100uF 25v (PANA EEU-FM1E101)
C45 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C46 - Original .47uF 50v / Now .47uF 100v (WIMA MKS2D034701E00JI)
C48 - Original 3.3uF 50v / Now 3.3uF 63v (WIMA MKS2C043301KKSSD)
C49 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C50 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C53 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C54 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C55 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C56 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C57 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C58 - Original .47uF 50v (LL) / Now .47uF 100v (WIMA MKS2D034701E00JI)
C61 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C62 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C63 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C64 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C65 - Original 10uF 16v / Now 10uF 25v (NICH UKL1E100MDDANA)
C66 - Original 10uF 16v (not on parts list) / Now 10uF 25v (NICH UKL1E100MDDANA)
C78 - Original 4.7uF 25v / Now 4.7uF 35v (NICH UKT1V4R7MDD)
C84 - Original 10uF 16v (not on parts list) / Now 10uF 25v (NICH UKL1E100MDDANA)
C91 - Original 10uF 16v (not on parts list) / Now 10uF 25v (NICH UKL1E100MDDANA)
C92 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C97 - Original 10uF 16v (not on parts list) / Now 10uF 25v (NICH UKL1E100MDDANA)
C101 - Original 1uF 50v / Now 1uF 63v (WIMA MKS2C041001FJC00)
C102 - Original 10uF 16v (not on parts list) / Now 10uF 25v (NICH UKL1E100MDDANA)
C103 - Original 4.7uF 25v (LL) / Now 4.7uF 63v (WIMA MKS2C044701M00JO)
C104 - Original 10uF 25v / Now 10uF 35v (NICH UKL1V100MDDANA)
C105 - Original 1uF 50v (NP) / Now 1uF 63v (WIMA MKS2C041001FJC00)

Before:

After:

 

[Super Noob]

Some LEDs:

Dial

Indicators:

 

[Super Noob]

Finishing Up:

Bias

Offset:
(on channel drift +/- 10 mV and other is very stable at less than 2 mV.

Top View:

 

[Super Noob]

105 Capacitors: 79 Aluminum Electros, 23 Low Leakage Electros, 2 Tantalums, 1 Film
17 Diodes
3 Zener Diodes
4 Variable Resistors
1 Potentiometer (replace broken one)
10 LED Lamps
55 Transistors
1 Relay

Finishing Shots:

Just breaking in... sounding very solid across the board.

Guess what is up next...

 

[Watthour]

If the 8050 was fun to work on...

 

[turnitup]

Wow, that’s a lot of work! I’ve got a 8050 too. Wish mine was in as good of shape as yours now is!

 

[Super Noob]

If the 8050 was fun to work on...

I chased a power hum... that would develop after about 2 minutes. Checked all the grounds and finally found a original solder leg near the filters touching the large output heat sink after I pretty much went through and replaced all the transistors in the process. My inexperience didn’t beat my persistence, but it was close.

 

[rickl]

that is impressive amount of work. Thanks for posting.

 

[sparklow]

A fine job. I am working on a KR-5030. I have a question on the small bulbs used in the function lights, stereo, Fm, etc. Do you have a part number and possibly a source for these? Thank you for any help with this as I have not been able to source them.

 

[oldboats]

A very nice write up. I will be referring back to this in the future, and so I thank you for posting it.

 

[Super Noob]

A fine job. I am working on a KR-5030. I have a question on the small bulbs used in the function lights, stereo, Fm, etc. Do you have a part number and possibly a source for these? Thank you for any help with this as I have not been able to source them.

ALITOVE 20pcs 3mm 12V White LED Pre Wired Prewired 20cm Bulb Lamp for DIY Car Boat... https://www.amazon.com/dp/B06XJZWMJM/ref=cm_sw_r_sms_c_api_i_zKBEDb69RPSRA

These come with a dropping resistor and I bend the lead wire back through behind rubber base and solder to the tops of the projecting board posts. It takes some manipulation and some “making it work” skills but it turns out well.

Am sure you can buy better fitting more direct replacements - but these are what I used for my mini LED replacement.

Best of luck.

 

[cnyel1967]

Nice work....looks great!

 

[Watthour]

I recently received some small LEDs from a supplier which exhibit a lower color temperature (3,000°K) like an incandescent bulb, are about 4mm diameter, operate from 2.9-12VSC and 4-12AC with no problems. They are my new de-facto indicator for all but the very smallest of lamps. The 33VAC supply to the indicators on the 5030 may present a problem with the original 560Ω dropping resistor, but that could be changed to suit the circuit with the lower current LEDs.

Similar pieces can be found here: https://www.parts-express.com/12-vo...tz-sansui-kenwood-yamaha-sony-5-pack--070-130

 

[sparklow]

ALITOVE 20pcs 3mm 12V White LED Pre Wired Prewired 20cm Bulb Lamp for DIY Car Boat... https://www.amazon.com/dp/B06XJZWMJM/ref=cm_sw_r_sms_c_api_i_zKBEDb69RPSRA

These come with a dropping resistor and I bend the lead wire back through behind rubber base and solder to the tops of the projecting board posts. It takes some manipulation and some “making it work” skills but it turns out well.

Am sure you can buy better fitting more direct replacements - but these are what I used for my mini LED replacement.

Best of luck.

Thanks, I will be ordering some of these.