Rotel RSX 1055 Power Up Failure

[d.kozminihs]

Hello there

I have purchased used Rotel RSX-1055 amplifier today and it got some serious issue.

It just won't power up fully. When i push the power button the blue power button goes on like it normally should. Then I press the Power button on a remote - it clicks once, the power LED goes OFF and then ON again after few secs (this is normal behavior). But the screen stays blank, there is no any sound or noise from the speakers (if connected), and there is no second click (which normally turns on the amp).

I found several posts with similar problem, but no solutions or adequate suggestions. I know it could be the only way to take it to some sort of dealer or service, but I want to give it a try myself

I have opened the main cover and found some dodgy marks around the capacitors on the Amp board (do they look ok?).

People say there are two fuses - I have seen only one, and it's ok.

Any ideas out there?

Thanks for any advice
D

[wkhanna]

Welcome to the forum, D.

So sorry to hear of your misfortune.
I have moved your post to the Rotel forum to insure it gets maximum visibility from our Rotel experts.

[d.kozminihs]

Oh, Thanks Bill

[james.bujold.3]

If the amplifier ever went into overload the overload circuit protector maybe burnt in to an always on/off position that would be the first place I looked.. Find it on the circuitboard while the amp is powered on lightly tap the breakers and see if that will dislodge it.


Sent from my iPad using Tapatalk

[d.kozminihs]

I found the Service Manual, with all the information needed to make a copy however I failed to find anything like "Overload Protector" or similar. How does it look like? How does it look like on a blueprint? Is it something similar to relay? Is there some other reason a self-test would fail?

Thanks for your replies
D

[Glen B]

You won't see a device called "overload protector". Each channel's amplifier section has its own overcurrent sensor (transistors QL215, QC215, QR215, QSL215 and QSR215 respectively). Transistors Q217 and 216 also form part of the DC protection and overload protection circuit. Look in the power supply section for fuses F901 (main fuse, 7A 250V), F902 318mA 250V (standby power supply fuse), and F903 and F904 both 2A 250V.

[wkhanna]

Thanks, Glen!

[d.kozminihs]

Cool, I have found F901... it was dead. So I have replaced it, but the RSL232 burned with flames right after pressed the power button. Does this indicate, that QSL214 is dead? (am I right? No? Again no?)
Also... RSL seems to represent Resistor Surround Left (even though it is located in FR section according to instructions) - may I just cut it off somehow, and use it as Stereo only?
I can see 2SA1386A transistors for sale (to replace QSL214), but it's specified as 2SA1386A-OPY on the paper... does it make a difference?

May it be one of the capacitors, and bot the QSL214?

Also I guess it means QLS215 is Ok?

Thanks a lot for your suggestions!

[Glen B]

First, make up a "dim bulb tester" (a.k.a."poor man's variac") for use when powering up an amp with suspected shorted outputs, blowing fuses, etc. This is an invaluable tool for alerting you that there is a high current draw before further damage occurs. It employs a light bulb as a current limiter and indicator. Google dim bulb tester for more information.

Output QSL214 is probably bad, and possibly its driver, QSL212. If either or both are bad, to be safe you should replace the complementary output and driver QSL213, QSL211 as well. Sanken 2SA1386A and 2SC3519A should be available. Make sure any equivalents have identical specs.

[d.kozminihs]

Cool... So I have ordered all four transistors already. So I will try to find some time to get the old ones out to test them... unfortunately time is of a big issue for me right now.

I will keep you updated

Thanks for a "dim bulb tester" advice, I should have thought of that... I spoke to my father reg this amp, told him the fuse was gone, and the first thing he asked me - how did the fuse look like, burned black or just melted wire... and when I said it was burned black, he said - you never ever try to switch a unit ON with this kind of dead fuse, in a best case scenario it will just blow again, in the worst - whole system will... so that's what happened.

Thank You