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Sound dies randomly

Joehowes86

New member
Jun 25, 2014
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Hi,

I have a Rotel RA-930AX amp, randomly, the sound from the speakers will stop. At present I have a headphone jack to phono lead from the back of the amp to either my tv or ipod and unplugging it and plugging it back in gets the sound back, also turning the amp off and on brings the sound back.

another issue which is more frequent that both speakers stopping, is one...and it's random whether it's the left or right.

Against unplugging the jack and plugging it back in or turning the amp off and on corrects the problem...it's unbelievably annoying.

Any suggestions?

thanks for the help
 

Joehowes86

New member
Jun 25, 2014
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I was think he headphone socket but it's the same when plugged into the tv or ipod and I'm pretty sure it's done it when plugged into the ipad.

the cable is new but I guess it might be that...I can't think what might be wrong with the amp, funny turning the amp off and on corrects it without touching the cable.
 

Joehowes86

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Jun 25, 2014
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Vladimir said:
I'm thinking a relay needs cleaning. Have you tried different inputs on the amp?
I've just switched to the CD input and am testing that...I did get the amp second hand so it's gonna b a little old...is relay cleaning simple/cheap?
 

Overdose

Well-known member
Feb 8, 2008
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Joehowes86 said:
I was think he headphone socket but it's the same when plugged into the tv or ipod and I'm pretty sure it's done it when plugged into the ipad.

the cable is new but I guess it might be that...I can't think what might be wrong with the amp, funny turning the amp off and on corrects it without touching the cable.
That narrows it down to the cable or amp sockets on that input. As suggested, try another input for the cable.
 

Vladimir

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Dec 26, 2013
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It's simple for a service tech, but not so much for someone who hasn't done anything with electronics.

If the problem is gone with the CD input it is possible that there is a cold solder joint. Common problem with age and easy fix by resoldering the joint.

Worst case scenario you have a faulty opamp or output transistor on its way out.
 

Overdose

Well-known member
Feb 8, 2008
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Vladimir said:
It's simple for a service tech, but not so much for someone who hasn't done anything with electronics.

If the problem is gone with the CD input it is possible that there is a cold solder joint. Common problem with age and easy fix by resoldering the joint.

Worst case scenario you have a faulty opamp or output transistor on its way out.
Might not be too bad on this amp, it may have quite a lot of discrete components due to its age.
 

TrevC

Well-known member
Jun 12, 2013
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19,070
Buy yourself a can of this and squirt liberally into the headphone socket. No need to take the amp apart. Work it in by repeatedly plugging and unplugging the headphones.

http://www.ebay.co.uk/itm/Super-Servisol-10-Switch-and-Contact-Cleaning-Lubricant-/300946300533?pt=LH_DefaultDomain_3&hash=item4611cc1e75
 

Joehowes86

New member
Jun 25, 2014
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Vladimir said:
It's simple for a service tech, but not so much for someone who hasn't done anything with electronics.

If the problem is gone with the CD input it is possible that there is a cold solder joint. Common problem with age and easy fix by resoldering the joint.

Worst case scenario you have a faulty opamp or output transistor on its way out.
so far so good in the CD input...havnt had a chance to really test it for an extended period of time but had it on for 20/30 mins today and no issues, whereas yesterday it was happening within 5/10 minutes.

Do you think the amp might need servicing? I live in London, any recommendations?
 

Joehowes86

New member
Jun 25, 2014
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TrevC said:
Buy yourself a can of this and squirt liberally into the headphone socket. No need to take the amp apart. Work it in by repeatedly plugging and unplugging the headphones.

http://www.ebay.co.uk/itm/Super-Servisol-10-Switch-and-Contact-Cleaning-Lubricant-/300946300533?pt=LH_DefaultDomain_3&hash=item4611cc1e75
squirt it into the headphone socket on the amp? Is this a solution to fix the socket or generally clean the inside of the amp? i don't have any headphones with a 6.3mm jack to work it in.
 

TrevC

Well-known member
Jun 12, 2013
370
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19,070
Joehowes86 said:
TrevC said:
Buy yourself a can of this and squirt liberally into the headphone socket. No need to take the amp apart. Work it in by repeatedly plugging and unplugging the headphones.

http://www.ebay.co.uk/itm/Super-Servisol-10-Switch-and-Contact-Cleaning-Lubricant-/300946300533?pt=LH_DefaultDomain_3&hash=item4611cc1e75
squirt it into the headphone socket on the amp? Is this a solution to fix the socket or generally clean the inside of the amp? i don't have any headphones with a 6.3mm jack to work it in.
Just the socket. I'm presuming that the jack switches the speakers out when headphones are fitted. It might not, of course. If it has no effect you can open the amp and squirt the speaker relay with the same stuff, if it has one. It could also be a dirty tape monitor switch, have you tried playing with that?
 

Vladimir

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Dec 26, 2013
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If it works, don't do anything. Just general maintanance in London might excede more than half of the amplifier value second hand.

Cleaning all pots, switches and contacts with Servisol by yourself is a good idea as long as you have the amplifier plugged out of the mains socket for 2 hours first. Also don't spray capacitors, transistors or the transformer with spray, just potentiometers, switches and contacts (online youtube tutorials available). After spraying, excercise the switches and pots by turning and pressing, respray, excercise, repeat. Leave the amp open for 2 hours before closing the lid and plugging it back in.
 

Joehowes86

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Jun 25, 2014
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Vladimir said:
I've indicated the places you can spray with Servisol on this image.

wow thanks for the detail! I'm a little hesitant to start squirting the inside of my amp with liquid, how risky is it if I follow your instructions exactly.

i have had it open and replaced 4 fuses...and I did use to tinker with computers so I'm not completely new to this.

where exactly do I apply the servisol? For instance, in the picture, do I spray into the sockets for the speaker cables and phonos etc (looks like that from your pic) and on the other side, where do I spray, directly where the arrows are pointing?
 

Vladimir

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Dec 26, 2013
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I just aproximated with the arrows where the switches, potentiometers and connectors are located. You spray the switches and pots through the small openings of their metal shell casings inside. The RCA connectors and speaker terminals you spray freely everywhere where there is metal surface for contact with cables and jacks.

Use a youtube tutorial because visual demonstration will set your mind at ease more than just me typing here. This one is just one of the many tutorials. https://www.youtube.com/watch?v=0QvOepREO4k

Use the spray sparingly, don't let it gush all over the PCB board. The spray will evaporate so give it at least 2 hours with the hood open before closing the amp and pluging it back in the mains.

ATTENTION: The main capacitors hold charge of high voltage even after the amp is turned off. They are like batteries. Don't touch them, don't spray them.
 

Overdose

Well-known member
Feb 8, 2008
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Not sure if this is obvious, but do this with the unit switched off and do not turn it back on until the cover is back on and the unit is dry.
 

Vladimir

New member
Dec 26, 2013
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Overdose said:
Not sure if this is obvious, but do this with the unit switched off and do not turn it back on until the cover is back on and the unit is dry.
The main power cord completely unplugged out off the main socket.
 

TrevC

Well-known member
Jun 12, 2013
370
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19,070
Vladimir said:
Overdose said:
Not sure if this is obvious, but do this with the unit switched off and do not turn it back on until the cover is back on and the unit is dry.
The main power cord completely unplugged out off the main socket.
Ring the police and get them to set up a 4 mile exclusion zone around the house. After a month it should be safe to return.

:)
 

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