Help with trouble shooting

[CXC999]

My Rotel 1062 stopped working in standby, nothing playing, just was dead in the morning.

It keeps blowing the fuses F603 and F604 which are in the output lines of the transformer. Other fuses are fine. They blow immediately when pressing the on switch and the relays switches, no speaker or inputs attached. With help in another thread I got the Service manual with schematics and parts list, but little other descriptions. Weird that it blew without actually amplifying anything. Before I take it apart and test all components I wonder if someone can point me in the right direction about what could cause this behavior? Any help much appreciated.

[madtecchy]

posting the scehmatic would be a very good place to start

[c2cthomas]

Originally Posted by madtecchy

posting the scehmatic would be a very good place to start

It can be downloaded from here. Download the Rotel RA-1062 service manual for free - Hifi Manuals

It's a three page schematic so it would be hard to load here.

[c2cthomas]

F603 and F604 are the 1st fuses right after the power transformer secondary and pretty much feed everything. 1st suspects will be your power output transistors, power supply cap's and the diode bridge D901.

There is a section that instructs about bias adjustments etc. - but no troubleshooting guide. Isolate the power output section and get the power supply up and running 1st.

I'm saying that's what I would do 1st - not necessarily that there aren't better routs to take. Perhaps there is someone around that knows this amp well and can say - go right over here and do so and so.

[CXC999]

Thank you so much will proceed as suggested and see whether I can locate the culprit. D901 is only 90 cents.
Q902 2SB631K-EF $6.20
Q901 2SD600K-EF $ 5
I hope the problem is within that section.

How do I post schematics? Looks like I need an URL but don't see a way to store images here?

[gmphadte]

click Go Advanced

[c2cthomas]

Originally Posted by CXC999

How do I post schematics?

I am going to try post these - I don't know if they will come out large enough to be of use tho.

If you bring the image up by clicking in it you can use Ctrl and "+" or "-" to enlarge or shrink the image. Not ideal but looks like it works ok.

[CXC999]

Thanks, it maybe good enough for the experienced to get an idea. I still hope that someone fixed this problem before or has experience with Rotels. Looks like they are all fairly similar in architecture. A lot of people also try to mod them with better parts. Will take out the transistors and diodes to test on the weekend.

[CXC999]

Found that the output transistor Q902 is shot. Good call indeed. I hope thats all. Q901 and Q902 seem to run really hot looking at the surrounding discolorations and lifted leads. I guess I will put some heat sink on those.
thanks for the help.

[c2cthomas]

Hi 999 - I'm glad the info helped.

Here are a couple of links to some Rotel forums - I can't vouch for them but with the number of post there should be a few folks that know what they are talking about. Of course there is the probability that there will be some that should be approached with some degree of caution.

Rotel Owner's Thread - Page 10 - AVS Forum
HTGuide Forum - Club Rotel

If you found the shot xsistor it seems that you have at least some electronics knowledge and test equipment at hand. Do you have a variable AC transformer on hand (i.e. Variac)? They come in handy when you are firing up electronics equipment because you can limit the amount of voltage and current going to the unit under test and this could save you from smoking sum stuff up!!!

I like the ones that have a current meter on 'em.