Electrical Adjustments for D-15?

Well, some heat is normal, and there's kinda a fine line between what is considered normal, and what is excessive.

All of my slimline Discman's are warm around the PS, but nothing major.

Haha! Yeah, that's not good. In my experience, cheap unregulated adapters can be a few volts over when not under load.

Just out of curiosity, can you give me the model number of your Sony adapter? I wonder if mine is the same?

When you get the new adapter, check specifically if you still get 7.4v on that 6v measurement point.

 

Mine was warm EVERYWHERE, mostly under the screen(in other words everywhere except the battery slot and the optical pickup)

Sure, the model number is AC-930A.

Will make sure to do that.

And I had some breakthrough on your hypothesis, I noticed that the gain for the laser was too high and creates a high frequency sound when reading CD-Rs, which goes away when I turn down the gain(I've tried this a couple days ago but I didn't know why). Now I think that as a sign of the laser being over-driven! The new adapter should arrive soon.

 

Update on the adapter!
Link to the images
I suppose that the capacitor is dead and can't not smooth out the voltage ?
There's a huge 16V 2200uF capacitor inside !
I'll try to swap the capacitor and see it it works, if it does I'll try to 3d print a case for it because I had torn open the casing...
That's it !

 

Yeah that looks very suspicious. Congrats on opening the adapter! That's not easy to do. If capacitors are bad, ESR and the MFD deficit can cause all kinds of weird things to happen, but most likely not a higher voltage.

So, the capacitor is most likely not the cause, rather a victim of another problem, most likely the transformer.

My guess is the actual transformer is giving the capacitor more than it's capacity. Remember, that cap is rated for a MAXIMUM of 16v, and you are getting about that from the plug.

Upgrade to at least 25V 2200uf if you can fit one. More voltage is better. if you put a 16v in it, it won't last too long.

See if you can measure AC voltage directly out of the end of the transformer going to that convertor board.

BTW, my adapter is a Sony AC-940, it's held together by screws.

 

I actually destroyed the case but thanks.

I just got the new adapter which there's a little switch to change voltage on it. However it's still delivering 11V when it's set to 9V... I tried to set it to 7.5V so that it actually delivers 9V but then D-15 shuts down while playing. I'm going to file a customer's complaint because on the site selling this said it's regulated... And regarding the measurements, on the 6V point I still got 7.4V and 4.1V for the 3.4V point. Kinda defeated.

 

Well, it's actually normal to be a bit higher than 9v if off load. All of mine are a little higher off-load. the 11v should go down close to 9v when playing. Remember, your digital keyboard adapter was showing 13.5v and it's a 12v adapter. Even my Sony is 11v when off load. Remember, it's a lot better than 16v!

Keep it on 9v and see what happens.

 

Sure, that's reassuring!

Edit: I noticed when the discman tries to focus and read the disc the display flickers when first started up. Any ideas?

 

UPDATE ON THE HEATING PROBLEM:
I just got a pair of DT 770 pro 80ohms I ordered. Strangely I noticed D-15 is a lot cooler using this headphone. I use to listen with sony's WH-1000XM2. Is it possible that the heating problem is caused by an incorrect impedance of headphones? WH1000XM2 is 14ohms(passive, with cable), and is blasting loud even at the lowest volume with D-15. According to the formula I=V/R, Could WH1000XM2 be shorting the discman in a vague sense as it has such a low impedance which generates large current in the amplifier circuit? Thanks!

 

Very interesting! All Sony AC-930A adapters that I saw were held together by two screws. I have three AC-930A on my desk right now, you do not have to break the shell to open them for a recap, just use G4 security bit...
On the other hand, I have never seen genuine Sony AC-940 being held by four screws, all of them are glued shut and you do have to cut the shell to open them. @Recaptcha can you take a photo of your AC-940 for me?

Yesterday while working on Sony D-100 Discman ((Oh My! How many transistors and diodes can be burned in one unit?!?!!!)) I decided to be more scientific about my statement about D-150 'warmness'
Flat-surface probe attached direct to the metal bottom of D-15, Red-Book CD put on infinite replay, 120Ohm Sennheiser HD-570 plugged in, volume set at high but still bearable volume of '4':


After an hour of play temp rises from 23C to 30.6C, in another hour it reaches 32.3C and stays there. Even without a probe you can easily check if your Discman-Baby has a fever, i.e. hotter than 37C, as all mommies do... with a palm of your hand

But from your observation on flickering display it is a safe guess that there is a problem with Discman's power supply, you should get a regulated power supply and start poking around Discman's voltage regulators and DC-DC converters. Start with @Recaptcha suggestion, those transistors do most of the work, get hot and go bad often. Later model, D-250, got this part redesigned and upgraded.

 

Ya know what? I just checked and the adapter IS held together by glue. I guess I was thinking of another adapter? Wow, how stupid of me not to double check it... Ol well.

Anyways, yeah, the power supplies in these Discmen (mans) do tend to have issues that can lead to display flickering.

Very scientific check here, @nev4eh8959, you should try to replicate this and see what you get. As @Jorge mentioned, you should be checking the important transistors and regulators along the path and see where abnormal readings pop up. That's the only way I can think of to troubleshoot without an 0-scope.

While we're on the subject of scopes, since you seem to do a lot of work with electronics, you should learn and purchase an analog oscilloscope. I recommend a 4-channel model preferably with a trigger. This can help out majorly in your troubleshooting adventures especially when lasers and IC's are concerned.

 

Thank you for your help!
Sorry I was busy cuz a test is coming up

Geez I actually destroyed the housing... What's G4 security bit? I couldn't find anything like it online so I gave up and used violence...

I forgot to mention that it only flickers with the new adapter with adjustable voltage. It didn't flicker with AC-930A How can I find a proper adapter? Any suggested models that can power D-15 without a problem ?
My guess is that because the adapter is not stable enough to deliver constant voltage and current so D-15 is unhappy. However about the warmness, I'm sure it's higher than 37 with both adapters. Again I'm not sure I can diagnose this buddy without a proper adapter so I wish I could have some suggestions on finding one.

@Recaptcha
Thank you for your reply too !
As I said I still can't test is properly because I can't isolate the issue. Do you know any adapters that work well with D-15? Thank you!

I think so too! Are there any models that you suggest? I really need one to fix these players !

Also if there are any SMD components that's bad, should I replace them with a hot air station or quikchip (or something I don't know)?

Thank you!

 

Yeah, you could get an AC-940 like mine, provided it's not registering a higher than normal voltage.

I have a TekTronix 2245. It's a 100mhz 4 channel with a trigger. Mine's been completely gone through, and it's on a Tektronix K212 cart. I also recommend the accessories bag too. I also found an Tektronix blue power strip and mounted it to the back so I could use it as a mobile station and plug in other test equipment.



Yeah, I know, she's bit hefty! But I love her.

As far as SMD goes, the answer to your question is: VERY CAREFULLY. I've replaced SMD transistors without anything more than a soldering iron and some tweezers. That's also why I'm seeing more gray hairs atop my head lately.

Maybe another member @Jorge can share his experience with SMD stuff. I understand he does a lot more of it than I.

 

Now we know who is hiding behind your mighty JBLs I have to hide my toys from The Boss in my Lab, but she is ever vigilant: pops up at some random times to check that I keep windows open and do not breathe solder vapors and also that I do my actual work (to pay the bills, you know... which has nothing to do with electronics!!!)

@nev4eh8959 : take some photos of what you have and I will work you thru your basic needs. But... If your goal is to get one working Sony D-15 Discman then the cheapest way is to sell yours "for parts" for $80-100 and to buy a restored one for $200

your avatar reminds me of my fav tune




an update on Sony AC-930A adapter that you destroyed: yesterday I opened three of these to install fresh Nichicon 2200/35V UFW audio-grade caps (measured at 2150uF @ 0.07Ohm) and the caps that I removed from the adapters measured 2206, 2188, and 1937 uF at 0.12, 0.03, and 0.02 Ohm....: there is a good chance you thrashed a perfectly good Sony adapter for nothing...

 

Haha! I was referring to the oscilloscope being hefty, but hey, I get it!

I actually keep the JBLs in a separate room, my music room, and the oscilloscope lives in my game room (along with about 15 gaming consoles and a 1989 JVC 27” CRT)

Also, my secondary SONY audio system lives in my game room as well. I mean hey, you can’t truly enjoy Star Fox 64’s wide palette of SFX without a good sound system!

 

Ha! I have no idea what you are talking about, but already feel Old about that ... and silly me, those are not JBLs, now with my reading glasses on I can see it

 

Oops. Sorry, It's just weird video game stuff...

Haha! Yes, those are not the JBLs, they are my cheap Sony’s. Although they only retailed for about $300/pair new, they don't sound too terrible.

What I don't understand about tower speakers these days is that they have an array of about 5 or 6 speakers in them but still don't sound as good as an old monitor with only 2 or 3 speakers.

 

I'm 57 and I know all about Star Fox and the famous Super FX IC. Just don't ask me about any later than the PS2.
The only Games console I ever bought new was the N64 which at the time made most PC graphics look very lame.

If you want to feel really old, on BBC Radio 2 Sounds of the 80s is now followed by Sounds of the 90s.
The 38 year presenter keeps making comments like "When I was ten me and my friends worked out a dance to this one".

Recaptcha. I wonder if you have any idea how much that scope was new. I the mid 80s I persuaded the department I worked in to buy the equivalent Philips
four channel scope as we kept borrowing one as it was so useful. I recall it cost about £3000 at the time - half my annual wages ! Knowing Tektronix the cart you have was probably several Hundred Dollars.

 

Love the Super FX chip! Love the SNES Star Fox as well although I haven't tried the Star Fox 2 game for SNES that was never released until 2017. It uses the Super FX 2 chip and it wasn't released at it's target year of 1995 since the N64 was looming and Nintendo wanted to move on from SNES. Then, for the SNES classic edition, it was finally released. SF64 had groundbreaking SFX and voice work for the day!

I'm not sure about my scope's original value. I suspect it was pretty high end, but I'm not sure. That sure is a great story about your Philips Scope. The 4 channel scopes are VERY useful. I imagine the cart was pretty expensive. It works very well for me because I don't have enough space to keep it on my bench, so the cart is nice for that purpose. Plus, it makes it look more beefy, and who doesn't like that?!?

 

Update on my discman repair journey:
I tried more adapters and D-15 flickers still. The problem is in the machine itself. I accidentally tore off a pad of a resistor when I was replacing the capacitor on the power board, I scraped the trace very carefully and solder it back. I'm going to test the resistor's resistance and it's connectivity. However this happened at the very beginning of the repair and it doesn't explain why the screen doesn't flicker with the original adapter...

@Recaptcha

Okay ! Thanks !

Thanks for the suggestion! I might buy it one day (when I can afford it !

Totally agree, I feel like these precise repairs are killing my brain cells haha.
Thank you !

@Jorge

Sure! Thank you so much!
Schematic
1) I can't find Q401, Q402 and Q413 in the circuit schematic so I don't know how to measure them. They are marked as regulators.
2) Should I measure Q433? The measured voltage seems to be the battery voltage. Or should I measure along the red line from the power jack? (8.6v 7.4v etc)
3) Have you ever used this to remove SMD components? Does it work ?

I fix for passion ! Of course I'm trying to have a discman but that won't stop me to take my time to fix it ! I've learned so much !

OOPS. OUCH.

Thank you !

 

please remind: what do you mean by 'original adaptor'? you have a photo?

1) they are on the mini-board with power jack. Do not bother, they are for battery recharge. If any get hot just desolder, they are not needed for normal play
2) same as above (Q433). And Yes, Do That! Also, with your finger (use rubber gloves) check where heat is coming from. In my last D-15 one it was bad Q409/Q434
3) Yes, I did, Yes, it works... but NO: this is not a ChipQuick low-temp solder. What you need is ChipQuick Solder Removal Alloy