Technics SU CH90 CD skipping lets find out why

A common cause of cd player skipping is a gummed up optical block. Especially if the unit has sat unused for a period of time.

[@bbourgeois4698]

Hi, I'm the owner who had Dave look at this CD skipping stereo. It's now working like a new machine. Thanks, Dave!

[@12voltvids]

Your welcome. Hopefully many more years of service left in it.

[@Hi-Tech-Ray]

B Bourgeois thanks for allowing him to film the repair for this video.

[@Hi-Tech-Ray]

12voltvids if we can’t access the grease you’re using from that plastic package, what other alternative grease could we use?

[@12voltvids]

@@Hi-Tech-Ray its mollykote and it is available. I just have some small packets that came with vcr service parts way back.

[@arjunmoses4315]

I guess it's pretty off topic but does anyone know of a good website to watch newly released tv shows online?

[@stevenk195]

I did this procedure on a Panasonic RX-DS750 boom box that was built in 1996. It definitely needed the worm drive cleaned and re-lubed, but it didn't fix the skipping problem. Mine had a weak output on the laser. Luckily, that laser adjustment can be accessed without taking unit apart. Insert CD, select something around track 6-10. Stop it and remove CD. Head will be aligned where you can get a small screwdriver in the gap on the left side of head to adjust the potentiometer. Mine just took about a 10 degree counter-clockwise adjustment of the screw. Stopped skipping after that. Thanks for the video!

[@KingNast]

I still have my first Technics CD player from 1991. It's a standalone unit, and it also started skipping at one point. I'll have to take a look at it now

[@illusions2142]

Having same issues with a Kenwood so hopefully following advice from here i may be able to fix the issue

[@hestheMaster]

If it sits around for any time the lens will be dusty. Did you noticed where there was a change of height there was a long covering of dust on the top of the assembly as well. A lot of people bought these units back in the day. This is usually what happens to most of them and excellent video on the fix!

[@saarike]

Simply excellent! My humble thanks.

[@emoniz2007]

Mine Technics SL-CH510 had a cd skipping problem. i'm not a pro in these and replaced laser lens and the problem still the same, the grease looked good to me and the movement of the lens module looks ok. put the CD spinner motor working and a strange noise of bad motor. Replaced and voilá! Thanks for your sharing!

[@johncunningham5435]

I ran into some units where they attached the worm gear to the motor; usually the gear was plastic that would harden and crack over time making serving much more of a challenge.

[@Amberstargazerofearth]

Well, I have Panasonic SU CH80 (it looks exactly like this Technics!!!), and noticed the same CD track skipping issues only with CD-R. Thanks for vid! I'll do the same service operations to fix my lovely retro friend )

[@technixbul]

My favourite brand, my favourite type of electronics, on my favourite channel - perfect combo! ;)

[@galc8142]

Love your vids, thank you

[@djijspeakerguy4628]

Interesting mechanism. Looks similar to the one in my 1991 Technics SL-PD607 5 disc changer (which also has the MASH DAC,) except mine has a solenoid/linear servo that moves the laser, which is nice because there are no gears that can break.

[@Machinerium]

Hi! What kind of grease are you using? Thanks , great video btw!

[@markmurray5619]

Taking a look at the "eye" pattern will give you good info on the health of the laser. The manual will give you the amplitude as brands differ. Usually around 1 volt ptp.

[@12voltvids]

Not so much the amplitude, the diamond pattern needs to be clear. That was much more important on CD players with manual adjustments. This one has digital servos so nothing to adjust.

[@tacofortgens3471]

Only for manual servo cd players. New cd players all have a digital servo that you cannot adjust

[@Peppermint1]

My Panasonic unit has 3 small dampening springs attached to the electronic board, impossible to remove without breaking the center pin. On the other side, if I tilt the whole radio forward, the CD player starts playing perfectly smoothly.

[@deanzelensky9037]

I always oil the front bearing on the spindle motors. If you've gone this far it only makes sense to me, Another example would be a tape deck if you have access to the capstan bearing why wouldn't you oil that as well with a little sewing machine oil or better yet some full synthetic motor oil. Just some thoughts here.

[@chylogurti]

Great video again. Might have a play around with my hd301 Thank you

[@t-rodshader9593]

I have a panasonic cd Player from the mid 80's and im sure your familiar with the panasonic/technics (matsushita) based cd Players with the brushless spindle motor and very quick loading. But I might need a little info on one. Its the fact that it keeps making a constant frequency noise from the linear tracking coil on the optical block. But it does function. The other issue is that sometimes it does nothing at all. It will do the common motor thrust on power up then nothing else. But after cleaning and lubricating. I tried barely tweaking the laser diode adj a hair then back to check it and it read the disc almost immediately but wont play. Just keeps spinning slowly. But its a brushless motor that rotates freely so its definitely up to the signal generator to drive the correct speed id think. And im not sure how to adjust or approx where the adjustments should be since there are 8 or 9 adjustments to this model. If you happen to know anything about these id be happy. I do but not sure on adjustments. I was going to use a scope but its not where my scope is at the moment and i do beleive in most service manuals and matsushita cd Players you do need to jump a couple connector to ground and use a little box to make proper adjustments unless you just know about where they need to be and tweeking them. Which would be possible if you can get it close. But i just need to get it close enough to play since everything else looks fine. If you can help id greatly appreciate it. And i can send you the model no. And some pics or maybe a quick vid to show you the issue. I dont want to take up to much of your time but i know you have experience with matsushita products and i do as well but could use guidance on these particular settings. But i can make most adjustments. I love these cd Players and most of their products especialy certain models in particular so id like to get this one going fairly soon so i could enjoy it and pull out some others i havent used in a while as well. Its been sitting a few years. Id like that. Thanks.

[@zx8401ztv]

I hope you and your other half have a healthy and happy xmas :-) I wonder how many people keep there cd's clean on the underside, muck is worse than fine scratches as the lazer can't get through it. Yes i know there is a complex error correction system but it will only cope with so much crap.

[@12voltvids]

Finger prints and smudges are the enemy of all optical playback.

[@sarasartori6859]

"Thank you and happy Christmas to you too"

[@DorianPaige00]

It won't read through dirt as that is opaque.

[@frankreiserm.s.8039]

How can I use colorful, incandescent Christmas lights in electronics when I build electronic test instruments and power supplies? Frank

[@chilledoutpaul]

Hi dave, I had a technics unit like that but it was real old and it had one if these fluorescent multicolor "wow factor" displays, But it had no display and I couldn't see any slight glow from the filaments anyway after checking it had a direct ac supply via 2 fusable 10 ohm resistors from the transformer. after checking it out one if the resistors one of the resistors had gone o/c probably through age, anyway all was fixed and is still working now Anyway Dave happy christmas mate and "hopefully" a phrouerous next year. Paul from the British Empire! lol

[@750kv8]

Vacuum Fluorescent Display.

[@sivajisivaram2013]

Mine is Sony D-V500, VCD player not using for last 2yrs, not reading disc replaced lens also same problem. Disc spins more than normal speed. What may be the problem

[@ArthurThug]

I am from Brazil and I have this sound model SU-CH90 assembled by the name Panasonic, it has a single video on my channel, funny the device is from the 90s and the sound is nice to hear in 2020.

[@badcamm69]

Thanks Dave (been watching your videos-excellent ex Schlumberger Tech) for the cassette switch and cd advice got my Panasonic Sa AK330 shop cadillaking. What belt drive assortment would you suggest buying for general multi purpose shot in the dark -lol- use ?

[@12voltvids]

Look on eBay for some cheap multi pack belts. Usually a pack of 40 assorted will yield a half dozen useful sizes.

[@badcamm69]

@@12voltvids square round flat ? Whats your $uper chat ? Once again THANKS

[@oldskool1979]

I wouldnt even use grease in our cold climate for car cd players....it hardens too much

[@AzizAkbiyik]

Hello, my Sony CDP-M43 M54 CD player skips when the bass gets louder. Could the reason be that it is greaseless? What other reasons does it cause skipping?

[@janzacek9996]

hello friend. I changed the optics RAE 0152 to TECHNICS sl pd 687... the optics have protection? the optics are changed but the cd does not spin.. where could be the problem.thanx

[@jasonthewiczman5442]

I was never one for all built in components I like separate components poinner is my first choice

[@pliedtka]

Sometimes I had problem where the burned CD wouldn't track properly at beginning or end of CD. No problems with original pressed CDs. Then again some players are more immune to scratched CDs than others. I still use early 90s Sony that won't read all burned CD-Rs but the components quality inside is very high for mid price unit and has all the funtions including indexing.

[@12voltvids]

CD players from before cdr were developed have problems reading many burned disks.

[@pliedtka]

@@12voltvids I know. Still wouldn't mind top of the line CD spinner with multibit DACs from 90s, not those idiotic designs available now with only power, load/eject, play and stop, and rest on the remote control. www.soundfountain.com/amb/cd25years.html

[@markmarkofkane8167]

Wonderful! A new video!! Happy Holidays! I have a Sony (2008) all in one System. The CD drawer won't open. Luckily, no CD is inside. 3 disk changer. (Bottom of unit) Probably the belt, but I can't see it.(I took the side panels off) It would probably need a major disassembly. And I am not sure I can do it. The Radio works fine. And the aux input also works.

[@12voltvids]

I have 2 R-R units awaiting their turn on the benck.

[@petertryndoch8857]

I thought that the capstan motor would be a stepper type. So how does it maintain an accurate speed? Does it have weights on contacts that go open when it spins too fast like in ye olde turntables? But I don't think so. Does it regulate the voltage to the motor? Or none of the above.

[@KingNast]

The data is read into a buffer, so I don't think the speed has to super accurate. It just has to spin slower when the laser is at the outer edge of the disc. It probably just varies the voltage to the motor

[@12voltvids]

The motor has a voltage regulator to control its speed. Some motors have servos, but not this one.

[@Bluethunderboom]

Speaking of the Solder Wick, instead of the copper wick that will work to siphon the solder off from the board, will the aluminum wick siphon the solder out from the board two? Speaking of the music, haven't you heard any music from Bath And Body Works from MP3 player that has the music from 2007 or 2008? I don't know that you're interested to know what that is. =/

[@12voltvids]

Solder will not flow onto aluminum.

[@tvpartscompany8197]

repair in cd player find out why you do good job

[@wayneg296]

👍👍😎✌️

[@cengeb]

Grease matters!

[@scotttait2197]

That spindle bearing did not sound ok and spun down kind of quickly looking at the video

[@carman7503]

Hello dave. I have a koss ks4122 that stopped playing dvd's, i changed the laser pickup, leveled the laser table with a bubble level. The laser has two pots, one for cd and one for dvd, i was able to get to play all cd's and cdr by adjusting the pot cw. The dvd started out no spinning the disc, then i adjusted the pot cw and now only 1 dvd will play, no other dvd's will play, i have found with different small cw movements i have approx. 2 dvd's to play. The main board has no focus or tracking pots on it, do i find the rf point and adjust the dvd pot for maximum vertical output with the least vertical jitter. I have a 10mHz scope, is this good enough to view the eye pattern. I would like to get the player to work again. Any help would be appreciated.

[@12voltvids]

They all use digital focus / tracking these days. Your spindle motor is likely the culprit.

[@carman7503]

@@12voltvids i replaced both the spindle and the sled motor, no improvement, but these motors were used. How do i adjust the dvd pot, is there a procedure for this, this adjust and try is time comsuming, i might be overshooting it. Is it a precise adjustment, i have the resistance measurements of the pots when the laser was first put in. Maybe i remove the cd loader and position it above the table and adjust the dvd pot while watching a movie, still have to find the rf test point. I can not find any service info on this dvd player, but i think there should be others that have the same two pots. Do you have any service info on this type of laser pickup. Thank you again for answering my question.

[@cengeb]

I finally got a desoldering tool, from Hakko, vacuum power, as it heats, works better than wick, or solder suckers..

[@12voltvids]

That is something on my wish list but I don't do enough work to justify it. At least that is my reasoning for not buying one.

[@chrisst.germain9007]

@@12voltvids Just buy it, you'll love it! Adjustable heat, you can change tips for different hole sizes. It 's so much quicker. I damaged a $4000 industrial PCB desoldering the typical way, but never again. The best tools aren't cheap, but I've never regretted having one, either.

[@tech45]

Amazing, I can fix things that weren't made to be serviceable:)

[@12voltvids]

These were serviceable.

[@dacus7]

Fun jog down memory lane, but who is still using a shelf system CD player like this in almost 2020? Almost no one judging by the large number of these I see for around $14.99 at Good will.

[@12voltvids]

I see many still in use at work. For some people space is a premium and these systems fit in perfectly.

[@djijspeakerguy4628]

I have an Aiwa in the garage, but the Sony kss-213f-based 3CD player on that one is mechanically broken. I use it for FM radio and can plug my phone into it. That one, however, sounds better than any of my Bluetooth speakers, but that is because the Aiwa speakers I am using are from their flagship model, far better than the typical Aiwa speakers.

[@cengeb]

Dust on the Lens, wasn't that a song long ago?

[@rogerturner1881]

there are 2 types of skipping..1/skips tracks [which i think is more common] 2/skips WITHIN the tracks 2 to 6[which is more rare]-this is my problem i have a Technics PG 4 [2000] and it started doing this a few[3] years now...what could be the problem from Greece

[@12voltvids]

Most likely the spindle motor is worn. The bearing wears out and causes vibration at certain speeds which shakes the disk and causes tracking errors

[@rogerturner1881]

@@12voltvids could a new laser help...i cleaned it and it worked a time, then it started.

[@pinarellospeedracer]

It would be funny after all of this work on this unit that the hole time the CD was skipping was caused by a bad CD.

[@dobermanguy9437]

Sometimes you can have it defective CD I have a Pink Floyd CD that looks perfectly normal no scratches looks brand new in one of my CD players it ejects it instantly on the other CD player it plays but right in the middle it starts to skip so I did a little test I played 15 other CDs that I have completely from start to finish no problem that's telling me right there there's a problem with that Pink Floyd disc like I said I played 15 on the other CDs and no problem sometimes you can get a defective CD people and it's nothing to do with your player

[@12voltvids]

There were tons of bad CD. Look and see if it was manufactured by Cinram. They made tons of CDs and DVD s that were difficult for certain players to read and they read fine in others.

[@user-fh9mq3ux4n]

All CD's will skip eventually .

[@aarontrupiano9328]

so this is likely why my walkman is skipping. it was fine the last time i used it years ago.

[@aarontrupiano9328]

@@Runco990 hah i bet

[@toddt6730]

After recieving a lot of our warranty replacement lasers, SONY engineers told us to clean the laser with alcohol and use a circular motion to avoid scratching the lens

[@12voltvids]

I have done that too. When smokers had CD players, a smoke film stuck to the lens and obscured the light.

[@tacofortgens3471]

Had a system like this from sony, in less than the cd plauer lens was worn out. They are junk

[@dacus7]

A Bluetooth speaker would take up a lot less space and be sonically superior to most of these old shelf systems. Don't get me wrong though. I enjoyed your video. I've done hundreds of similar repairs on game console drives. That is where you see lots of gummed up worm gears, worm out laser pickups, and frozen turn disc motors.

[@12voltvids]

Most people over 40 don't use bluetooth speakers. Hell I have a dozen bluetooth speakers that have been sent to me over the years and you know how many I use? None! Why, because my music is not on my phone. I also don't buy onto subscribing to any music services. I either own the media, or listen to regular broadcast radio.

[@musicnerd72]

@@12voltvids I couldn't agree more! 👍

[@750kv8]

Chances are that, the customer has a bad CD, maybe that's all.

[@DorianPaige00]

probably not as many lasers/decks get sporadic issues where the disc doesn't skip in the same spot. If it skips in the same spot and you can see light shining through the disc, then obviously it's skipping from damage to the disc.

[@ronbradshaw7404]

Bee Pee Cee

[@oturgator]

I think the amount of labor that you put in to this set was may be quadruple more than it’s value.

[@bbourgeois4698]

I think that you are wrong. The stereo now works like when it was new!