Hi guys,

first i unsoldered C97 which seems to be ok (8830uf measured with Fluke 115, ESR i cannot measure), then D22 which died definitely. Looking at D30 - i would test with external power supply current limited (e.g. 0.5A).

For D22 i already ordered SS36 to replace the original SS34 type - i keep you informed as soon as i got the spare parts.

thanks for your help

Peter

👍
With a bit of luck your unit will be fine after replacing D22 only.
The Beo guys really did go a bit too low with the 40V Schottky:

Nominal trafo out (24V + 10%) x SQR(2) = 37.3V  😠

37.3V max nominal level at D22 is scary. That leaves barely any headroom for surges from the grid or transients from inductor switching.

Hi,

D30 is ok. I replaced D22 and powersupply works now.

The original fault described in my first post ist still there, thus the powersupply might have died due to this error (after some time 3-5 minutes, the device shuts down with a "plopp").

Eventually a problem in the motor control unit? I disconnected the energy to the motor control unit (Cable P9 on PCB 3) and radio is now working, but i wonder why the display is not working (when radio is switched on, standby led turns out, but the display stays dark...).

I already checked +5V Display, that is ok. Should i use my scope to look at the display signals?

Any tipps how to proceed further?

Thanks

Peter

Peter wrote:

The original fault described in my first post ist still there, thus the powersupply might have died due to this error (after some time 3-5 minutes, the device shuts down with a "plopp").

The first step is taken. Congratz!
No, this diode did not die from an overload coming from a connected board. First, the switching controller limits the output current to 1.8A and the back EMF coming from such low current is easily handled by that Schottky. Besides, when a diode fails of over-current it usually fails open. If it fails due to over-voltage, it tends to fail shorted.
It is more likely that a random power surge caused the input voltage to rise beyond 40V and that's what killed D22.

I've seen there are other threads on troubleshooting the laser and the CD circuits of BS9000. You should study those and see if that relates to your issue.

Since you have a scope, of course you use it!! First I'd check all output voltages from the power supply. See if there is a high ripple on any of those rails. If there is, it's a sign of overload in that path OR (and that's important) a sign that the output cap on that supply rail is deteriorating or failing. Fix this! Ripple can cause all sorts of problems in digital electronics, e.g. your display issue, random erratic behaviour, etc etc

If the startup procedure of the PSU works, then you might be able to use the testmode by using the testpoint. 
If you’re not getting the BS9000 in testmode with a Beo4, then this can give you more inside by shorting the testpoint to ground before switching on the  power. Some faults can be caused on a different location than you might expected at first. 

Thanks to manfy and beobuddy for the hints - actually the device works again but i do not know why...

There was no ripple on the voltages so power supply seems to be ok. All Voltages are a little bit to high (Main Voltage 32,7 should be between 25-30V, 5V, Motor, Lid and Display at 5,2V should be 5.0)

I succeded in turning on testmode with Beo 4.

Test mode 27 showed Errors ML ERR 32, IIC ERR 104, CD ERR7, SLC ERR 42, APS ERR5 and PWR ERR 20.

After some fiddling i succeded in playing a CD with TM 67 !

Test 71 failed and refused to move the sledge - perhaps because of the missing lid?

After installing the glass lid there was still ERR 42 which seems to have something to do with finger protection system.

Test 71 started, opened the lid and closed it back again but did not move the sledge as supposed.

Suddenly, i dont know why - test 71 succeeded an actually the unit works again.

Only when the sledge ist moving it scratches slightly over the CDs (I adjusted the CD mechanism for flat level surface). After CLEAR ERRS in TM 27 they did not show up again.

Since i want to use the Beosound in a vertical position on the stand - should i adjust the clamper arm in horizontal position or better in the vertical operating position?

Thanks a lot for all your hints!

Hello, 

I followed this topic with deep interest because i have the same problem only some other problems remain. Hello,

I would like to reopen this topic because i had the same problem and some other problems still remain.

I have a BeoSound 9000 mk1 suddenly it was completely dead. I managed to repair the power board thanks to your hints (broken mosfet TR37, leaky capacitor C97, diodes D22, D30 etc).Diode D22 is changed it to an SS36 instead of an SS34. Now the standby led lights up. The main relay clicks. The glass door won't move when i push the button (maybe faulty motorboard?) The transformer outputs at first 10V then when the relay clicks 30V. When i push radio the standby led dims and the attached BeoLab clicks on. But nothing happens and the BeoSound goes back to standby. When i push cd all the red lights next to each cd lights up, but the sledge does not move and the lcd remains off. As i measured the 12V line on the powersupply pcb does not come up at booting. Does someone have experience in what components likely to cause trouble so the 12V line does not work?

I tried to go in test mode with the beo 4 but sinds the lcd does not light up i don't think this can help. 

Any ideas please?

Kind regards 

Kenny

I thank you

Kind regards

Kenny

Hi Kenny,

did you check all the lines on the powersupply? There are four separate switching regulators for +5v, + 6v, +12v, -12V (see schematic posted by hemenex).

My Beosound 9000 unit behaved also strange, sometimes the door wont move, sometimes the led display did not work. I suppose, this was influenced by the protection unit since after cleaning these errors disappeared.

Good luck!

Peter

Hi Peter,

Thank you for your answer. I didn't check the 25-30V line. So i started with a measure at P9 pin 1 and measured nothing. So i unplugged both fuses F2 and F3 to eliminate a couple of components. Just C98 and C23 were attached at p9-1 with the regulator D21. I measured 35V at D21 but not at P9 so there must be a bad connection in between. Eventually i found the problem. Sinds i had a leaky capacitor i replaced every elco capacitor on the power supply. By changing C98 (the big one 15000uF) i must have damaged the via. Sinds the board consists of more than two layers there was no connection anymore due to the bad via. So i soldered a couple of bridges, mounted everything and the sledge slightly vibrated so there was power!! :). Display remained dark but when i put the glass on everything came to life including display. So my unit is up and running. just the light (which illuminates the cd) in the sledge remains dark that is still something to look for and my glass door only opens with some help as i saw the rubber band slips. Now the unit is open i will also take a look at that.

I would like to thank everyone that posted tips in this topic because it saved my unit from the scrap yard.

Kind regards

Kenny

Bad news, the device was playing, i shut if off but the case was still open because i had to work on the gears of the door. I heard a sizzling and the door started to move up and down then the standby light went out again :( the device is dead again. After a quick look capacitor c143 leaked and is shorted to ground. and so is the -12V line shorted to ground.  I still have my 5V lines but no +12V or -12V at P2. The 12V on the 25-30V line is still present (on p9). I hope the microcontroller isn't toasted because there is a strong smell there, it could also been from the leaky capacitor. Back at zero. I keep you guys posted from my findings.