Rotel RMB-1075 blows left front fuse

[R_J]

Re: Rotel RMB-1075 blows left front fuse

The schematic has the value, its 33 ohms, and looking at the size its a .5 watt this should work digikey PPC33BCT-ND

[zacheriaj]

Re: Rotel RMB-1075 blows left front fuse

Thank you RJ. I didn't initially see the value on the schematic.

[ngvuanh]

Re: Rotel RMB-1075 blows left front fuse

Correct me if I'm wrong.
By reading service manual, you should check Q210 to Q217 since F401/402 are for this channel because of K11A.

[R_J]

Re: Rotel RMB-1075 blows left front fuse

Correct me if I'm wrong.
By reading service manual, you should check Q210 to Q217 since F401/402 are for this channel because of K11A.

Looks like the diagram is wrong and K9a & K11a are reversed. The fuse's 401 & 402 connect to N4 & P4 of S4B which connect to the Left front amp where the blown parts are located
The right front amp is working (according to O/P) where q210-q217 are located

[zacheriaj]

Re: Rotel RMB-1075 blows left front fuse

Replaced the bad output transistors and R425. Didn't see any other issues during testing. Unit powered up fine and passed all tests. Once it warmed up, I let it run about 60-70% for 45 mins with no issue. Customer is thrilled. Thank you everyone for the help!

[R_J]

Re: Rotel RMB-1075 blows left front fuse

It's usually a good idea to check and adjust the bias after replaceing parts in the outputs. Its easy to do (page 4 of the manual). if the bias is off one way or the other it could cause distortion or excess heat, even if it seems to sound ok.

[zacheriaj]

Re: Rotel RMB-1075 blows left front fuse

It's usually a good idea to check and adjust the bias after replaceing parts in the outputs. Its easy to do (page 4 of the manual). if the bias is off one way or the other it could cause distortion or excess heat, even if it seems to sound ok.

Thanks for the tip RJ. But I beat you to it didn't really need but a hair of adjustment

[kaboom]

Re: Rotel RMB-1075 blows left front fuse

Where did you get those "sanken" devices?

That old Japanese stuff is often faked, knockoffs usually have "shiny" tabs:

http://sound.westhost.com/fake/counterfeit-p2.htm
http://sound.westhost.com/counterfeit.htm


If you didn't run it up to full output into a dummy load, which would've "exposed" counterfeit parts, you've not finished the repair/troubleshooting.

[zacheriaj]

Re: Rotel RMB-1075 blows left front fuse

Where did you get those "sanken" devices?

That old Japanese stuff is often faked, knockoffs usually have "shiny" tabs:

http://sound.westhost.com/fake/counterfeit-p2.htm
http://sound.westhost.com/counterfeit.htm


If you didn't run it up to full output into a dummy load, which would've "exposed" counterfeit parts, you've not finished the repair/troubleshooting.

I have. And I don't think that anyone here would question ti the quality or validity of Digikey components.

[kaboom]

Re: Rotel RMB-1075 blows left front fuse

What about thermal compound? I don't see any oozing from the micas.