Technics SL-PG400A CD Player repair attempt 

It's good to know that these problems may be caused by dead capacitors, I will make sure to check the next time I have problems with a CD player based on the CDM4 mechanism. I don't think I have ever had any problems with CDM4 mechanisms, except for the ones in the four Technics SL-PG series CD players I have had over the years...

​@@DrCassette I saw a similar trend with the Philips CDM12.1 successor to the CDM4/19: CDM12.1 on Philips or Marantz CD players are mostly still fine, CDM12.1 on technics CD players are easily dead (e.g. PG370 and forward)

@@enricoself2256 , not necessarily. I have a 23yrs. old SL-PG 380A, bought used (but in good condition) 15 yrs. ago.. It works fine.

The next time I get in a CD player with CDM4 mechanism I will be sure to check the capacitors on the servo board.

You are lucky that your CD player only needed its laser cleaned - these players tend to have problems with bad capacitors on the board below the mechanism as I later found out...

@@DrCassette ive had it since i think 1992, first problem, love this machine

Thank you :)

You are right, I checked C2521 and it is indeed bad. Measures 20 µF instead of 47 µF, and the ESR is 16 Ohms. The CD player has already been scrapped, but the next time I come across a non-functional CD player with CDM4 mechanism, I will make sure to test and replace that capacitor. I have made a follow-up video testing that capacitor which I will upload soon.

Thanks I've fixed mine.. I used 47 25v upright n a, dart to scratch off that seal stuff n it's perfect I got a spare from car amp n estended wires with a cheap blacksur soldering iron... The inset was hardest part two white wheel s mounted too back posts.. But it's fine n worth it

I know I'm late but I've been having the same issue, I had to use a 50v capacitor instead of 25, but after tweaking the laser a bit the disk inside stops spinning after 2 seconds but the display still shows zeroes everywhere and nothing works... Does it have to be exactly 25 volts in order to work? EDIT: I tried to play again with the laser and focus a bit, it seemed it started working again at first, just a little skippy on some tracks but it was playing, then as soon as I started playing another normal CD the hard-knocking issue was back and it was struggling reading. I am considering to throw it away as well because I don't know what else to do and I've been reading that particular Philips mechanism has a very bad reputation (now I know why)

The camera indeed made the display look a lot better, in real life some segments were so dim they were almost invisible.

@@DrCassette Yeah, experienced that with my Sony ~CandyHam~ I mean HandyCam! Repairs were unsuccessful, but then again, I needed the entertainment, so, thanks for uploading!

Thank you :)

I was hoping that just a small turn of the laser current adjustment would be enough. It only turned into random adjusting when a small turn didn't do anything... The CD player has been scrapped, but the mechanism with servo board has been put into storage for parts. I will make a note to check the capacitors before using that assembly.

As other people have pointed out in their comments, these problems can be caused by bad capacitors on the servo board. The next time I come across one of these CD players I will make sure to check those too.

In the follow-up video I found that the problem was caused by a bad capacitor on the board under the CD mechanism. So if your CD players ever develop a problem, check those capacitors. They are easy to replace.

@@DrCassette I've checked the second one but thanks!

This, and also look for any failing electrolytic caps around the servo circuitry and on the power rails to the servo circuitry, voltage ripple there would play havoc. Generally, if a laser is failing, it’ll skip/mistrack until it can no longer maintain focus at all, at which point it won’t spin the disc up because it can’t detect a disc there. The spindle motor doesn’t turn when there isn’t a disc present, so if it does spin, the optical sensor is detecting a focussed laser beam. It really amazes me how many people automatically assume that all CD reading issues are down to a failing/failed laser, quite often, it isn’t the case, especially on these early Philips mechanisms, and mechanisms such as the Sony BU-1, KSS-151 etc, they were/are incredibly reliable.

I totally agree. I had skipping issues with my Technics cd player and i had checked everything but the motor with no luck. I finally sprayed some contact cleaner on the motor axle and problem solved!

My thoughts too a well known issue.

I second that suggestion: best case, it is half of the original capacitance; worst case, it is a dead short or has weird unpredictable behaviour

The CD player has now been scrapped, but the mechanism with servo board has been put into storage for parts. I will make a note to check the capacitors before using that assembly.

Thank you :)

I would suggest testing all voltages the display needs to work. Heater voltage and the high voltage fed to the display driver circuit. If the voltages are fine, the display itself may be at fault. Starting in the 90s, the quality of these VFDs became more and more random. Some still look like new, others go dim. In later years, Technics' parent company Matsushita (Panasonic) was known to use bad VFDs.

The spindle motor gets lazy draws too much current and can't get up to speed.

@@glpilpi6209 This is not true. I found the solution. Look for the "metal can" capacitors on the board that is attached below the laser mechanism. Change any of these blue Phillips caps. Job done! Enjoy!

For cleaning the case of HiFi components I usually use an alcohol based window cleaner.

@@DrCassette you can make a video clean a cassette deck player or receiver amplifier

No, I am not going to make a video just about cleaning. That is trivial.

@@DrCassette you are correct , what you think if I ship a defective Brazilian brand Cassette Deck player ? I have brands like GRADIENTE or POLYVOX. You not need pay or return the player ,. What do you think?

Thanks for your generous offer, but shipping from Brazil to Germany would be prohibitively expensive...

Klingt für mich nach Mechanismus. Der Laser steckt wahrscheinlich in Spur 0 fest und mit dem Fokus kommt man nur ca. 20-30 Sekunden weit und springt dann. Vielleicht ist auch das Schmiermittel vom Laufwerk verharzt. Was passiert, wenn du den Laser Pickup manuell von der Mitte nach außen bugsierst? Findet er seinen Weg zurück nachm Einschalten?

@@senilyDeluxe werde ich demnächst Mal ausprobieren. Danke für den Tipp 😉

Over the years I have had two Technics CD players with the linear magnetic drive, one was an entry level model, the other was the fancy SL-P770. Both of them worked, I gave the entry level model to a friend who I think still has it. I sold the SL-P770 because I had paid quite a lot of money for it and I didn't want to wear out the laser and ruin the value of the device...

I once had a Harman kardon disk player that behaved the same way. I service said the laser was worn out. Probably those lasers work better when it's a bit hotter.

Sounds like you have a problem with the limit switches detecting the position of the CD drawer.

Laser unable to find focus . Shuts everything down. Weak laser or photo diodes in the the laser block failing to provide signal for the focus servo loop.

It later turned out the problem were some capacitors that are hidden on the servo board under the CD mechanism.

The service manual makes no mention of any adjustments on the laser assembly itself. The laser power adjustment is on the servo board.

@@DrCassette There should be always one on the head itself, check it, the laser assembly head is showed as one whole module in Service manual, you won't see it described there, If not there then, another weak point is bearing on the spindle motor, you can replace it with any similar size motor with long enough shaft to fit the disk holder. The motor is tired and causing wobble, change it and adjust that pot again. I've repaired dozens of those Technics weak players. Also try to lubricate old shaft, if you have luck, it may not be that weared.

@@technixbul on that Philips CD transport, no. Laser power and focus adjusting pot's are only on servo board.

@@realsomething2981 yes i saw that, i have 3 of them, but this must be an older one, but the other part of my advices are still truth for that slide assembllies..

There is one specific capacitor in these CD players that needs to be replaced. There will be an extra video about that. However, replacing all capacitors is unnecessary.

@@DrCassette ;) OK!

@@DrCassette what do you do is this case buy a new laser or scrap the cd player?

@@brunomoyano8727 Scrap because the laser unit if you can even find one would be to costly

@@DrCassette so true but right now in my shop I have Sony portable radio from the 70s Sony used some really no name capacitor and found like 4 that were bad .

As I have said in the video, there was no missing spring. There are provisions for installing a spring, but Philips did not use them. That space is supposed to be empty.

I you look closely, on the right side of the CD clamp there was a spring. It seems when they designed it they intended to use two springs, but probably found that a stronger spring on one side worked just fine and saved a few pennies and install time.

Yes, I should have done that. But I originally expected only a small twist of the adjustment would fix the problem. In that case I would not have gotten anywhere near the fuse...

@@DrCassette I've found in the past that the half silvered mirrors under the lens can often be dirty and crazy hard to clean.

Some say the single laser beam was better at tracking scratched discs.

I repaired several CD players with either SONY or Philips Pick-up. I have a collection of dead Sony pick-up's (KSS240, KSS150, KSS213, ..) which needed a full replacement but I have yet to encounter a dead CDM4/19. In the ones where I checked laser output, they were all still perfectly within -50/-60 mV. So, yes, CDM4/19 are way more reliable than Sony transport. And if you need to find a spare CDM 4/19 they were used on a many CD players you can now get very cheaply.

Nope, it wouldn’t do that… it might kill the person touching the Allen Key though… made me very nervous watching it, even though I knew he hadn’t come to harm because he’d uploaded the video. Too complacent for my liking. I insulate any metal tools like that with electrical tape or shrink sleeve to prevent any shorting, and I keep my fingers well clear of any high voltage bits… I’ve been shocked after accidentally coming into contact with 240v mains and not been harmed but it can kill you outright.

The hex key was not as close to the fuse as the camera angle makes it seem. Everything was safe.

@@DrCassette glad to hear it buddy, it had me wincing lol. Seriously though, if you have a thin enough bit of shrink sleeve, just insulate the shafts of any allen keys or screwdrivers that you use for any trim pot adjustments, it saves any accidents from happening… I dropped a brick a few years ago when I dropped a screwdriver inside a Pioneer SX1250 receiver I’d spent rebuilding whilst it was setting the DC offset… I’ve insulted my tools ever since. It cost me many labour hours and quite a few parts to rectify that one. Luckily my customer was very understanding and grateful of my honesty… and he was delighted when he actually got his amp back.

Accidents like that are very unfortunate... I don't often come across adjustments that require a hex key, for most standard trimmer adjustments I have a set of ceramic screwdrivers with plastic handle, to keep everything well insulated.

@@DrCassette I learned from it, I do have some ceramic screwdrivers for trim pot adjustments, those are a great idea. I’ve got a few insulated allen keys too though. I insulate all but the tips of my probes too, I never want to make a mistake like that again. I went straight for the power switch but the damage to the output stage and power supply was instantaneous. Gorgeous amp once it was fixed though, gave my Linn amps more of a run for their money than I like to admit.

None of the SL-PG series CD players I had over the years would properly play CDs, but I now have to assume this was not because of a problem with the mechanism or the laser, but because of some bad capacitors.

@@DrCassette Which would be an important information for me as well. Thanks for posting the update video! OTOH, isn't the servo board (where you found the bad capacitor) also part of the complete CDM4 drive assembly, made by Philips, and so should be found in other CDM4-equipped players, regardless of brand, as well?

The layout and choice of components used for the servo board looks very different from the other boards in the CD player, so I would assume that this board was indeed made by Philips. But I don't know if these boards were a universal part for all CDM4 mechanisms.

I once had a batch of Ricoh CD-Rs. They wouldn't play in anything. I ended up having to adjust every CD player in the house and about every second CDROM drive. One wouldn't read normal CDs/CD-Rs after that.

@@senilyDeluxe I always use (during my childhood) Verbatim metal Azo, TDK reflex or Philips Silver premium Hard to write, but excellent read stability!

The Verbatim CD-Rs are indeed horrible, the reflective layer is so thin you can almost see through it.

Remember those super cheap CD-Rs that had nothing written on it? I used to write "This side up" on them... They weren't hard to read or write, but if you looked at them weird, the data layer would just flake off. And the data retention rate is maybe a few years.

Not recommended...

No, there was no problem with the drive belt. It was a problem in the electronics, caused by a bad capacitor. This has been discussed in another video I made.

@@DrCassette Hi yeah, I did watch the follow up video. I use a Technics SL-PG420A

Thankfully this is not too much of a loss, as it was in very bad cosmetic condition...

@@DrCassette I know people love that Philips swinging laser assembly, but at least a KSS-210 )or similar) is easy and cheap to find and replace!