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Sony MDS JB980 stuck on standby mode

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My MD/player is still dead. I did disconect all the wires and put it aside for a cuple of weeks, but it did not help. Then I took out the mainboard only to discoverr that Sony took a shortcut and did not wash the card after running it trough soilderingbath. So I cleaned it in redspirit and put id to dry up. Now it is clean like it is suposed to be. I mesured the resistanse from different voltages to ground. one of them sticks out. The system 3.3V has only 66 ohm to ground. So I have to digg in to that and find out why.

Here some before and after pictures of IC1 (Systemcontroll)

There is some dust on across some pins on the afterpicture, I took them away.

MDS-JB980_IC1 before.jpg

MDS-JB980_IC1 after.jpg

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Great to see you back Petter, and that you have not yet given up. Good point cleaning the board, thus removing potential capacitive "bridges".

Sony not cleaning these boards though is not necessarily a shortcut or ignorance - actually, can be quite the contrary. It all depends on the fluxes used. There are so called "no-clean" fluxes that do not require a cleaning step after soldering, and are widely used in the electronics mass production. Matter of fact, the industry has moved away from the water soluble fluxes on purpose for example, for several reasonable considerations. Nevertheless, cleaning the board is not "counteradvised" (unless a protective layer is required for uncovered copper leads, pads, or other areas).

3 hours ago, Petter Halonen said:

The system 3.3V has only 66 ohm to ground.

How and where did you measure it? On the assembled machine, or on the standalone maind board without anything else attached, or on the PSU board without anything attached?

The pure DC resistance of a power rail to ground might not give a reasonable information, unless the figure is down somewhere in the few ohms (close to shortcut) range. This 66 ohms to ground means 50 mA current on 3.3 Volts, that itself can be an acceptable figure, given how many IC-s are connected to this power rail. Even just the MCU itself can draw around 25...30 mA, and there are many others, like the VFD driver, the USB controller, the IR receiver, etc.

A counter check can tell you, whether or not your 3.3V rail is impacted: if the rail's DC volltage is spot on under normal condition, then probably there is no issue there.

Having sad that, since you are  in this machine so deep, I would recommend to take a "tour" around with an ESR meter, checking the filter caps at first.

Although you might be tired of the different ideas, might be worth keep trying. I think Stephen has already suggested disconnecting the USB board. Next, if you can desolder the IR chip. Or just disconnect the front panels' switches/leds/IR piece (yes, the Standby button is on it too, as well a the IR receiver, so the only means to switch the machine on is by inserting a disc, to see if it accepts it).

I know you tried nearly everything, still you may want to take a quick look at this list (that is not exhaustive, just a raw check list for the C13/DiscError issue), to see that nothing is left out. Some causes can be common in both failures.

We are fully behind you, and waiting for your breakthru - might bring some new information to this weird stuck-in-standby situation.

 

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I am afraid this is a wrong direction. I read again the whole thread, and based on your posts: you do have the system 3.3V and it is OK, and the MCU is working, since you can enter Service Mode and step back and forth. I break my brain but  I can only get back to here. I tend to believe this is not a problem you can catch with multimeter/oscilloscope. If the MCU is working, power rails are OK, then it is probably the MCU that keeps the device in standby for a reason. I am not sure if you have already tried to replace the OP, or if you have tried to disable the shutdown signal momentarily, or if you have tried to reset the settings in the Service menu, or if you have already checked the IR receiver circuit - just to exclude those possibilities too.

 

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shame he hasent access to another player, eg a working 480 to swap the drive units to see if that cures it, looks like he has been round the tecnically difficult, maybe time to try the simple ideas, in players in the past i found that originally there was a disc stuck inside and if it tried to eject because of a knackered belt and moved the disc a little and cannot reset it in play position, the result is deck is stuck in stand by, when ive seen a deck for sale with a mdm 7 unit and the seller says stuck in stand by, yep i know whats wrong with that, buy it take the lid off, push the disc out using the two white parts, the broader one first, only push about half inch or so then push the narrow one, the disc will come all the way out, replace belt and all is well again, its just a long winded way of saying the problem may not be as deep as you all think it is.

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The problem now is that it switches to standby and I can't even get it in to servicemode. The backup battery is defect, only 0.4V by the way.

There is no lite in the standby led. I only have 3.3V system and Back 3.3V.  But I will not give up ... The fault is probably very simple thing when I find it.

A friend of mine will bring over an Flir camera and we will try to disable the shutdown signal momentarily, just to see if something get to hot.

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5 hours ago, Petter Halonen said:

I can't even get it in to servicemode

Now this is bad news :-( .

5 hours ago, Petter Halonen said:

The backup battery is defect, only 0.4V

That's not an issue really. It just keeps the settings made in the Setup menu (but has nothing to do with what is set in Service mode).

You can desolder and remove that battery completely until you find a replacement, it has no effect on other functionality.

 

Edit: oh yes, the battery is also needed for keeping the TOC information stored in the memory but not yet written back to the disc, if a power outage happens.

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3 hours ago, Petter Halonen said:

There is no lite in the standby led. I only have 3.3V system and Back 3.3V.

The standby led not lit regardless you have the 3.3 Volts is strange at least. It is switched by the VFD driver chip (and supplied directly from the system 3.3V, the output of IC401).

Do you probably have a display chip issue?

To check this, you can try to disconnect the display section from the front panel board, together with the switches/IR/leds section - keep only the switches/encoder section connected via the ribbon cable to the main board. Plug the AC cord, and listen to the relay clicks. Hopefully you hear two. Then insert a disc to see if the deck loads it in, and if the disc spins. If it does, you can eject it with the eject button (or, actually, you can try pushing the Play button too).

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1 hour ago, NGY said:

The standby led not lit regardless you have the 3.3 Volts is strange at least. It is switched by the VFD driver chip (and supplied directly from the system 3.3V, the output of IC401).

Do you probably have a display chip issue?

To check this, you can try to disconnect the display section from the front panel board, together with the switches/IR/leds section - keep only the switches/encoder section connected via the ribbon cable to the main board. Plug the AC cord, and listen to the relay clicks. Hopefully you hear two. Then insert a disc to see if the deck loads it in, and if the disc spins. If it does, you can eject it with the eject button (or, actually, you can try pushing the Play button too).

Thank you for the advice. I tried this as soon as I read your advice, but no luck. still goes directly to standby and refuses to take the disc if i try to put in the minidisc.

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19 minutes ago, Petter Halonen said:

no luck. still goes directly to standby and refuses to take the disc

Sad. At least we learned two things: 1) it is not the IR receiver chip and 2) it is not the VFD driver chip that keeps the deck in standby. We must look then elsewhere.

I would turn to the OP now, but the fact you cannot enter Service mode is worrying me. You cannot really destroy your spare OP even with the settings for the present one, as long as you don't activate the higher laser power (recording), but it would be better to reset all settings in the setup menu prior to the OP exchange, then readjust everything step by step.

Giving a chance to replacing the OP might bring your Service mode back, and if it does, it probably solves the main issue too. Cross our fingers. Just don't try anything else with the new OP except trying to switch the unit on. If success, we go from there.

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48 minutes ago, NGY said:

Sad. At least we learned two things: 1) it is not the IR receiver chip and 2) it is not the VFD driver chip that keeps the deck in standby. We must look then elsewhere.

I would turn to the OP now, but the fact you cannot enter Service mode is worrying me. You cannot really destroy your spare OP even with the settings for the present one, as long as you don't activate the higher laser power (recording), but it would be better to reset all settings in the setup menu prior to the OP exchange, then readjust everything step by step.

Giving a chance to replacing the OP might bring your Service mode back, and if it does, it probably solves the main issue too. Cross our fingers. Just don't try anything else with the new OP except trying to switch the unit on. If success, we go from there.

I actually managed to get the standby led to lid now. I mesured on Q755 while I turned on the power, and the LED litt up.  But now it is dead again... 

only when I put it in to servicemode it looks like picture below.

servicemode.jpg

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4 hours ago, Petter Halonen said:

only when I put it in to servicemode it looks like picture below.

Can you please check one thing, what happens: keep pushing AMS knob and Rec button together while plugging the AC cord. This should work even on a stuck-in-standby device, at least whenever I tried in the past it did work. Normally, it brings up the display/leds/buttons/knobs/remote test sequence.

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On 7/26/2020 at 8:15 AM, NGY said:

Although you might be tired of the different ideas, might be worth keep trying. I think Stephen has already suggested disconnecting the USB board.

 

Hmmm, I see in the picture that the NetMD light is on. This is rather odd, is it not?

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13 hours ago, NGY said:

Can you please check one thing, what happens: keep pushing AMS knob and Rec button together while plugging the AC cord. This should work even on a stuck-in-standby device, at least whenever I tried in the past it did work. Normally, it brings up the display/leds/buttons/knobs/remote test sequence.

I tried this, what happens is nothing or leds litt up like last picture randomly. Also tried different buttons to see what happend and it is the same. I have tried to disconect USB-board.

Today I have got the Flir-cam so I will try to force the power on and see if anything get warm. I'll keep you updated.

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update: I managed to forse the power to say on,  by shorting Q911.  I used the FLIR cam to see if anythig got more warm than normal, but nothing got warmer than 42C which is normal for voltageregulators. Then I mesured all the voltages and everything is as it shuld be. So I guess this is the MCU that is messing things up because it detect or don't detect somthing. 

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2 hours ago, Petter Halonen said:

I tried this, what happens is nothing or leds litt up like last picture randomly

That's no good news :-( .

33 minutes ago, Petter Halonen said:

So I guess this is the MCU that is messing things up because it detect or don't detect somthing. 

Definitely. Hopefully it is not a shorted/burnt I/O on the MCU.

Do you have access to another 480/780/980, or one of the bookshelf units with the same drive (cannot recall the models, will check my notes)? A quick test by swapping the drives would tell us, if it is related to the BD board or the OP somehow. Without that, you can do the OP swap.

8 hours ago, sfbp said:

Hmmm, I see in the picture that the NetMD light is on. This is rather odd, is it not?

Indeed. I tend to believe we face multiple issues here that force the MCU keeping the device in standby. Let's see if exchanging the OP brings any result.

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What about that first picture? See the 5 pins that have had resoldering done on them - is it possible there's a short there (I see some what-looks-like-guck between the 1st and 2nd and also 2nd and 3rd). I've no idea which pin does what (I leave that to the expert detectives) but my assumptions are:

1. they are something important
2. someone worked on them before. Was that you, Petter?

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8 minutes ago, sfbp said:

What about that first picture? See the 5 pins that have had resoldering done on them - is it possible there's a short there (I see some what-looks-like-guck between the 1st and 2nd and also 2nd and 3rd). I've no idea which pin does what (I leave that to the expert detectives) but my assumptions are:

1. they are something important
2. someone worked on them before. Was that you, Petter?

It was defently not me resoildering them, I also noticed that, and mesured to see if there was any shorting. This pins (20 -25 ) are mostly 3.3V and clk signal or not in use and there were no shorings.

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  • 7 months later...

I've had the same problem and took a while to fix. I managed it by lifting the top of the drive up and closing (without taking right off as I didn't want to unseat the spring) then manually inserting a disc. This didn't work at first but jiggling the top to allow it accept the disc properly and then reconnecting (with the disc in place), turning on the power and it worked. Seemed it wasn't accepting the disc properly at first, as it wouldn't quite go all the way in, so wouldn't come out of standby. 

Sorry this may not help your case but in case others have the same problem. Thanks for those who suggested trying to reseat the top. 

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