Trace fault on Rotel RA930

orangedeuce · 12th November 2005, 07:07 AM

Dear all,
My Rotel RA930 when power up will need about 1~2mins before there is sound from the left speaker. Can you pls help to identify the components that I should replace? Thank you.

orangedeuce · 12th November 2005, 02:24 PM

Pls help!! pls help!!

Netlist · 12th November 2005, 02:29 PM

I'm not familiar with the amplifier and from the provided photo I can see nothing wrong at first sight. Capacitors 'look' OK.
Are there output relays on the board? Did you check for bad solderings?

/Hugo

orangedeuce · 13th November 2005, 09:37 AM

Thanks Hugo.
I did clean up the board and check for bad soldering.
sorry, I dun know what is a output relay. Can you explain a little so that I will go trace?
Appreciate your help.

Netlist · 13th November 2005, 09:54 AM

Although it will be hard to trace the fault without schematic, you could provide one or two more pictures. One overall view of the amp's inside, as close as possible and one of the solder-side.
It looks like a fairly simple design and perhaps there's only a mute circuit acting as a protection for DC at the output. The components in the top right corner of the first picture could be that circuit.
What measuring equipment do you have at hand?

/Hugo

orangedeuce · 13th November 2005, 02:03 PM

Thanks again for your help mate.
I have a multimeter and attached are 3 pictures. Hope that they are good enough, else I can always take more.

First picture:

2nd picture:

3rd picture:

Netlist · 13th November 2005, 02:06 PM

Looks good, I'll see if I can distillate something.

/Hugo

Netlist · 13th November 2005, 02:41 PM

Make sure the amp is turned off.
With your DMM in AC mV range connect the ground lead to the black wire between to two big caps as seen in your first picture (fky6h4). The other lead should go to TP3(-) and for the other channel TP?(-).
With the volume knob at zero, apply a signal to the amplifier, switch the amp on and turn up the volume a little bit, say 1 or 2 if the dial goes to 10.
If the meter responds for both TP's, you have a big chance that only one of the two output fuses has a bad contact. Both output fuses are the glass cylinders located nearest to the big capacitors.

/Hugo

Netlist · 13th November 2005, 03:16 PM

Just above the opamp TL072 you can see two capacitors.
On the third picture (fn4hnm) you can see some kind of stain surrounding them. If you have no idea where it comes from, (spray can to clean contacts?) they might be leaking. Change them and clean the pcb with isopropanal or some alcohol you have at hand.

/Hugo

orangedeuce · 14th November 2005, 09:19 AM

Thank you. I will follow the steps and feedback the results. As I am currently out of town, I will have to do it once I am back home.

12th November 2005, 07:07 AM	#1
orangedeuce diyAudio Member Join Date: Nov 2005	Trace fault on Rotel RA930 Dear all, My Rotel RA930 when power up will need about 1~2mins before there is sound from the left speaker. Can you pls help to identify the components that I should replace? Thank you.

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12th November 2005, 02:24 PM	#2
orangedeuce diyAudio Member Join Date: Nov 2005	Pls help!! pls help!!

12th November 2005, 02:29 PM	#3
Netlist diyAudio Moderator Join Date: Jan 2003	I'm not familiar with the amplifier and from the provided photo I can see nothing wrong at first sight. Capacitors 'look' OK. Are there output relays on the board? Did you check for bad solderings? /Hugo

13th November 2005, 09:37 AM	#4
orangedeuce diyAudio Member Join Date: Nov 2005	Thanks Hugo. I did clean up the board and check for bad soldering. sorry, I dun know what is a output relay. Can you explain a little so that I will go trace? Appreciate your help.

13th November 2005, 09:54 AM	#5
Netlist diyAudio Moderator Join Date: Jan 2003	Although it will be hard to trace the fault without schematic, you could provide one or two more pictures. One overall view of the amp's inside, as close as possible and one of the solder-side. It looks like a fairly simple design and perhaps there's only a mute circuit acting as a protection for DC at the output. The components in the top right corner of the first picture could be that circuit. What measuring equipment do you have at hand? /Hugo

13th November 2005, 02:03 PM	#6
orangedeuce diyAudio Member Join Date: Nov 2005	Thanks again for your help mate. I have a multimeter and attached are 3 pictures. Hope that they are good enough, else I can always take more. First picture: 2nd picture: 3rd picture:

13th November 2005, 02:06 PM	#7
Netlist diyAudio Moderator Join Date: Jan 2003	Looks good, I'll see if I can distillate something. /Hugo

13th November 2005, 02:41 PM	#8
Netlist diyAudio Moderator Join Date: Jan 2003	Make sure the amp is turned off. With your DMM in AC mV range connect the ground lead to the black wire between to two big caps as seen in your first picture (fky6h4). The other lead should go to TP3(-) and for the other channel TP?(-). With the volume knob at zero, apply a signal to the amplifier, switch the amp on and turn up the volume a little bit, say 1 or 2 if the dial goes to 10. If the meter responds for both TP's, you have a big chance that only one of the two output fuses has a bad contact. Both output fuses are the glass cylinders located nearest to the big capacitors. /Hugo

13th November 2005, 03:16 PM	#9
Netlist diyAudio Moderator Join Date: Jan 2003	Just above the opamp TL072 you can see two capacitors. On the third picture (fn4hnm) you can see some kind of stain surrounding them. If you have no idea where it comes from, (spray can to clean contacts?) they might be leaking. Change them and clean the pcb with isopropanal or some alcohol you have at hand. /Hugo

14th November 2005, 09:19 AM	#10
orangedeuce diyAudio Member Join Date: Nov 2005	Thank you. I will follow the steps and feedback the results. As I am currently out of town, I will have to do it once I am back home.

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