Hi, a few observations on the potentiometer repair - I believe according to the ALPS design. 1) The retaining ring on the shaft can be removed normally, there is no need to grind it off and it can also be reused - I made an opening tool for this - by sharpening a dental spatula - super hard material - I loosen the individual lamellas by rocking them and after removing them I straighten them back. 2) I use socket wrenches to refit - this allows me to choose the exact size according to the size of the ring. 3) I test the resistance path with a curve tracer, or an analog voltmeter with a needle, or with an oscilloscope - on a digital Ohm meter you can overlook a small break in contact due to the recalculation of values. Nice amp and nice repair 👍 Nice day 🙂Tom
Thank you for the excellent video. I have removed the volume pot from a couple of these and can Confirm that this is a huge job and not for the faint of heart. I have a spare one of these that I salvaged from an otherwise mostly obliterated model 600. It has been several years ago, but I decided to take it apart and clean it up and do some basic testing to see if it was still good. When I got to the volume detent section one of those yellow plastic pieces will still in place and it was on the “stop” tab, but was very brittle and basically crumbled when I touched it. I think you are correct and that the other one goes on the tab right above the roller to keep it from falling out of place should someone get overzealous rotating the volume knob. I thought about working a piece of thin walled clear plastic tubing over those tabs, but I decided against it. Anyway, I reassembled it without doing anything other than cleaning it and the detent feel is still perfect.
Yes. I removed all of the plastic debris and reassembled it without doing anything else. The feel is still perfect. If I had to guess I would say that the metal spring loses some tension. And allows the Roller to fall out.
In addition to the feel, the yellow plastic was floating around inside of the control which caused it to occasionally get jammed up. In this case I needed to go in anyways so figured I might as well make it click again.
I always wondered about what would be involved in taking these apart- thanks for doing a great job with the video and excellent description. Nice to have a bunch of small ball bearings around and that one worked so well. I hope I never come across a situation where I need to do this, but now know what is involved 😅
Thanks Ben. This is great. I do see why they used a roller. On mine, I think those plastic pieces are floating around and will occasionally jam the control, especially if the whole unit is moved.
Nice to see you are doing potentiometer repair in the proper way, on the other international channels every1 is just spraying deoxit inside, just one advice for the future, carbon tracks should remain dry
A tiny blob of a tacky grease might assist in keeping the ball bearing in place. And lubricate the ball to reduce wear on the gear. Might be safe, as far as dust accumulation or grease "wandering" goes, since there are no tracks on that wafer.
The original roller style pin had more surface area against the plastic teeth. The new ball bearing might end up wearing out the teeth in the middle over the years, as it has a very tiny spot it presses against in the middle of the tooth.
The yellow "plastic" was the cushion/spring between the roller and the tang. The steel the roller was in was not meant to be the spring, it's just the holder for the roller. Without the roller in there the ball will cut a groove in the teeth. A piece of soft urethane cut to shape would have been ideal for the cushion/spring.
I learn something new every day. Thank you for the advice. If I come across a completely working control in the future I may disable so that I can try to make a replica of the plastic piece.
@@NovaluxStereophonic If I were you, I'd schedule some time, once you get your ideas in place, and re-enter the control to that level, and improve/finalize the work there - get the roller back in and stabilize it all, then re-assemble it. The ball will wear a groove in the teeth, as said above.
We use alot of the same hand tools craftman pliers 3rd set for me, now i use mostly Knipex.. Snap On Ratchting Screwdriver .. I have found that the Engineer tools form Japan are Quite Good.. I highly recomend Wera Kraftform percision screw drivers.. Do you use JIS Phillips bits or screwdrivers for the japanese gear ? I Found Rocket sockets watching your work , so just thought I could share some tools you might find usefull.. You are a Truly a Very Talented young man ! Most of the guys working on this old equipment are retiring getting older . Have you ever thought about taking on an apprentist ? best regards, VG
@@vaporghost5230 Thank you for the kind words and tool recommendations. I do use JIS drivers when I remember. I have some Japanese made ones and I have a JIS tip for my ratcheting driver that I use on occasion. I don’t think I have the temperament to take on an apprentice but maybe someday. If you really want to up your tool game check out my friend’s channel. @primehifi
The front 2 gangs are balance. The next two gangs work like conventional volume attenuator with loudness tap (As the audio enters the preamp. The rear gangs control the output level of the preamp before it goes to the power amp. Kenwood's idea was that if the volume is controlled at the beginning and end of the preamp block the noise floor would be reduced.
Hi, a few observations on the potentiometer repair - I believe according to the ALPS design.
1) The retaining ring on the shaft can be removed normally, there is no need to grind it off and it can also be reused - I made an opening tool for this - by sharpening a dental spatula - super hard material - I loosen the individual lamellas by rocking them and after removing them I straighten them back.
2) I use socket wrenches to refit - this allows me to choose the exact size according to the size of the ring.
3) I test the resistance path with a curve tracer, or an analog voltmeter with a needle, or with an oscilloscope - on a digital Ohm meter you can overlook a small break in contact due to the recalculation of values.
Nice amp and nice repair 👍
Nice day 🙂Tom
Thank you for the excellent video. I have removed the volume pot from a couple of these and can Confirm that this is a huge job and not for the faint of heart.
I have a spare one of these that I salvaged from an otherwise mostly obliterated model 600.
It has been several years ago, but I decided to take it apart and clean it up and do some basic testing to see if it was still good. When I got to the volume detent section one of those yellow plastic pieces will still in place and it was on the “stop” tab, but was very brittle and basically crumbled when I touched it.
I think you are correct and that the other one goes on the tab right above the roller to keep it from falling out of place should someone get overzealous rotating the volume knob.
I thought about working a piece of thin walled clear plastic tubing over those tabs, but I decided against it.
Anyway, I reassembled it without doing anything other than cleaning it and the detent feel is still perfect.
Thank you for sharing your experience. Were you able to leave the original roller in place without any of the "plastic" material in place?
Yes. I removed all of the plastic debris and reassembled it without doing anything else. The feel is still perfect.
If I had to guess I would say that the metal spring loses some tension. And allows the Roller to fall out.
I was on pins and needles the entire time you were taking that push lock washer off. Amazing work as always Ben!
Brilliant repair. I wouldn't have risked it just for the feel and the sound but I understand wanting it to feel like new.
In addition to the feel, the yellow plastic was floating around inside of the control which caused it to occasionally get jammed up. In this case I needed to go in anyways so figured I might as well make it click again.
Bravo pour ce travail de restauration, potentiomètre difficile à trouver aujourd' hui .
I always wondered about what would be involved in taking these apart- thanks for doing a great job with the video and excellent description. Nice to have a bunch of small ball bearings around and that one worked so well. I hope I never come across a situation where I need to do this, but now know what is involved 😅
Thanks Ben. This is great. I do see why they used a roller.
On mine, I think those plastic pieces are floating around and will occasionally jam the control, especially if the whole unit is moved.
Great camera work 😊
What a beautiful piece of gear. ❤
Reminds me of the Rotel RA1412 volume and balance and its lovely detented clicks.
Great work as always, Ben. Your camera work is top tier too.
@@PrimeHiFi thanks!
Awesome. I was stressed out watching!
Nice to see you are doing potentiometer repair in the proper way, on the other international channels every1 is just spraying deoxit inside, just one advice for the future, carbon tracks should remain dry
Remain dry ? Realy ?? Not lubricate ??
@Marko-R Yes, really
A tiny blob of a tacky grease might assist in keeping the ball bearing in place. And lubricate the ball to reduce wear on the gear. Might be safe, as far as dust accumulation or grease "wandering" goes, since there are no tracks on that wafer.
The original roller style pin had more surface area against the plastic teeth. The new ball bearing might end up wearing out the teeth in the middle over the years, as it has a very tiny spot it presses against in the middle of the tooth.
The yellow "plastic" was the cushion/spring between the roller and the tang. The steel the roller was in was not meant to be the spring, it's just the holder for the roller. Without the roller in there the ball will cut a groove in the teeth. A piece of soft urethane cut to shape would have been ideal for the cushion/spring.
I learn something new every day. Thank you for the advice. If I come across a completely working control in the future I may disable so that I can try to make a replica of the plastic piece.
@@NovaluxStereophonic If I were you, I'd schedule some time, once you get your ideas in place, and re-enter the control to that level, and improve/finalize the work there - get the roller back in and stabilize it all, then re-assemble it. The ball will wear a groove in the teeth, as said above.
BRAVO !
👏
This brings new meaning (and appreciation!) to the term 'knob feel'. Super fun video!
Good job. They don't make a replacement potentiometer volume for the Kenwood model?
🌏🇦🇺
No, This control was custom specified just for this unit.
Seeing this I miss my KA-701 that I bought i 1982 and sold fully functionally in 2013
We use alot of the same hand tools craftman pliers 3rd set for me, now i use mostly Knipex.. Snap On Ratchting Screwdriver .. I have found that the Engineer tools form Japan are Quite Good.. I highly recomend Wera Kraftform percision screw drivers.. Do you use JIS Phillips bits or screwdrivers for the japanese gear ? I Found Rocket sockets watching your work , so just thought I could share some tools you might find usefull.. You are a Truly a Very Talented young man ! Most of the guys working on this old equipment are retiring getting older . Have you ever thought about taking on an apprentist ? best regards, VG
@@vaporghost5230 Thank you for the kind words and tool recommendations. I do use JIS drivers when I remember. I have some Japanese made ones and I have a JIS tip for my ratcheting driver that I use on occasion.
I don’t think I have the temperament to take on an apprentice but maybe someday.
If you really want to up your tool game check out my friend’s channel. @primehifi
you should have put some grease in there on the ball, it might wear out the plastic gear
Never seen such a volume control! Explanations on how it works would be welcome.
The front 2 gangs are balance. The next two gangs work like conventional volume attenuator with loudness tap (As the audio enters the preamp. The rear gangs control the output level of the preamp before it goes to the power amp. Kenwood's idea was that if the volume is controlled at the beginning and end of the preamp block the noise floor would be reduced.
I have same alps potenciometer in my technics SU-A4 for cleen and repear.
That hard, yellow broken plastic used to be a soft squishy spring.
So Ben quick question would you or anyone you know be interested in a matching 650 supreme and KT9900. Both purchased in Germany at the PX.
Holy gangs batman
Dude! I would have absolutely destroyed that thing
I had that IA