Jvc amp clicking on and off problem

[Fishtails]

Hi people

I'm usually found in the turntable section, but I have just started having an issue with my jvc ja-s31 amp.

I have cleaned all the circuitry with that spray you get and also replaced the four fuses with the correct ones.

When I turn the amp on I hear the usual click that you get from amps and the the sound comes out of the speakers from my music.

Then about 10 seconds later I hear that same click noise and get no sound. There is still power to the amp,though.

Sometimes it will keep playing longer than others. For instance I just turned it on again and have been able to listen to it with no issues for about 15 minutes and still going.

Any advice is appreciated.

Thanks!!

[whitesmoke]

Fishtails -
That click you are hearing is from the speaker protection relay. What is happening is you either have some dc voltage on the speaker output, or the protection circuit mistakenly thinks you have dc voltage on the speaker output.
When the relay works properly, do one or both of your speakers make a popping sound? (this indicates some level of dc on the output).
With speakers disconnected, no input and the volume turned all the way down, you need to measure each speaker output with either an oscilloscope or a multimeter set on dc volts. The measurement should be zero volts or as close to it as possible. This is adjusted on each channel with the offset potentiometer (those could probably use a good shot of contact cleaner as well). You definitely need a set of schematics or a pictorial so you will not inadvertently be adjusting the bias pots.
If adjusting this does not help, get across the coil of the relay (they're usually 24 volts) and see if the voltage goes bye-bye when the relay drops out.
If not, you probably need a new relay. If the 24v does go away, additional component-by-component troubleshooting is indicated.
Good Luck..
Mark

[Fishtails]

Hi
Thanks for your response. However the click doesn't come from the speakers. It comes from the amp itself and happens regardless of the speakers being connected or not.

Cheers

[Rothwellaudio]

The relays are inside the amp, so that is where the clicking noise will come from. Yes, it won't make any difference if the speakers are connected or not, the DC offset on the amp's outputs will cause the relay to trip. Or possibly the relays are being tripped by something else, but the clicking is the sound of relays being activated.

[fscl]

Ftails, the service manual is on VE's sister site HFE (in the menu bar extreme right) = HiFi Engine and can be downloaded here:

http://www.hifiengine.com/manuals/jvc/ja-s31.shtml

Poke around relay RV-701, had a cold solder joint around a similar protection relay which repaired itself after reheating the contacts with a soldering iron.

Good luck.

Fred

[Fishtails]

Hi
This information about the relay is great. Thanks people!

Now I just gotta figure out what it looks like. So I might post a few pictures so I know which part to try soldering.

I know all about the insides of turntables but the inside of an amp is a mystery to me except for the fuses:)

[fscl]

Hi
This information about the relay is great. Thanks people!

Now I just gotta figure out what it looks like. So I might post a few pictures so I know which part to try soldering.

I know all about the insides of turntables but the inside of an amp is a mystery to me except for the fuses:)

Page 13 of 23 shows the circuit board of the JVC. This is basically the map of the internals. You may see numbers of the various components silk screened onto the printed circuit board, RV-701 can be found at the right hand side of the CB.

Open the unit and turn on, make sure not to short out any electrical contacts and carefully start tapping this relay with something plastic / non conductive. You may hear the sound come out of your speakers come on or off. If so, it's the relay. Power off, there appear to be 8 solder connections to this relay, reheat and make sure to get the connection to the CB nice and shiny. Do not overheat.

After the joints cool, try turning on the unit again. Hopefully, she'll come back to life. If not, you may have to troubleshoot / replace the relay.

Good luck.

Fred