Samsung HT-Z310 "protect mode" ORTP-616 problem I think. Help Please

[lars1]

Hi I'm Lars, sorry if this is in the worng section.

I'm trying to fix an old surround sound unit I have here.
It was fixed multiple times under warranty until it ran out.

I have pretty limited knowledge on electronics so if you have the time to help you may need to explain things slowly for me.

The unit was starting then shutting down and saying protect, this was with no speakers plugged in.

I removed the cover and through some trial and error found that if I disconnected the AMP pcb it would start and run a disc ect.


I then found on the main power board that # R91 a 1/4w 1k resistor was burnt, also found that a diode #D31 was blown in 2 pieces and 3 capacitors were also swollen on top C92 C93 and C94.

Now I replaced all these parts with new ones, It then didnt start at all just a flickering standby light which I think I read somewhere was a short circuit? Now if leave the AMP pcb plugged in and I cut the #D31 diode back out it would start again say protect and shut down.

If I disconnect the AMP pcb completely again (with the #d31 diode still not in there) it will start and run a dvd and can watch it on tv just no sound obviously.


Its not essential that I fix it just thought it would be fun and could save some dollars trying to do it.

Thanks in advance.

 

[KeepItSimpleStupid]

Lars:
It's very hard to troubleshoot over the internet and I don't think there will be a lot of help here.
What is your mains voltage where you are?
The capacitor failures may actually be because they are the wrong type. You need ones designed for switching power supplies which are usually designated as "high ripple factor". You don't want ones rated for 120 Hz.

On one surround sound receiver I worked on, it came back to the shop a number of times. I kinda acted as a consultant and only worked on amps and usually the tough ones. The surround channel IC amplifer kept blowing. I put a ZNR on the power supply and it never came back. The voltages were too close to the rail.

Can you look to the datasheets of the caps you replaced?

These https://www.digikey.com/product-detail/en/CGS222U075R2C/CGS222U075R2C-ND/1595966 aren't cheap, but I'd almosttconsider them if they
I also want to 2x the supply voltage.

"Protect" usually means there is DC (> 0.75 V) on the speaker terminals. I'd also put a ZNR across each cap. I didn;t size one.

 

[Nigel Goodwin]

The capacitor failures may actually be because they are the wrong type. You need ones designed for switching power supplies which are usually designated as "high ripple factor". You don't want ones rated for 120 Hz.

Nor really, you just need good quality 105 degree ones, low ESR would be helpful, but not essential.

The reason the original ones fail is because they fit the cheapest crappiest capacitors they can buy, and I've changed many thousands of them.

Personally I tend to stock Panasonic and Rubycon ones as replacements, and they never fail again.

 

[lars1]

Thanks for your honesty guys, I have found I am getting no 12v on pin 9 on the CN2 plug.

Im guessing that maybe the U31 voltage reg shorted and took out the D31 Diode, I was going to change it just to see if it helped but cant find one at my local store.

I guess Ill just keep researching see what I can come across.