Onkyo receiver/amplifier

[lmcancu]

I have an old Onkyo receiver/amplifier that has a small problem. When listening to FM, one of the channels (I think it is the right one) is very low. However, when listening to any other source (CD player, Satellite receiver, etc) everything works fine: right channel is as strong as left. Any ideas why this could happen? Could a bad cap cause this?

Thanks for any help

[smason]

Re: Onkyo receiver/amplifier

Depending on the design, could be as simple as dirty switch contacts.
I'd start by cleaning the switch that selects the input.

[Uranium-235]

Re: Onkyo receiver/amplifier

but fm is built in, right?

[lmcancu]

Re: Onkyo receiver/amplifier

yes, FM is built in. CD, and the other sources are inputs in the back of the unit

[smason]

Re: Onkyo receiver/amplifier

but fm is built in, right?

But still could be switched with a mechanical switch, since we don't know the model or how old it is....

I fixed an older Pioneer receiver a while ago where the left channel was dropping out. Was a dirty speaker a/b switch.

[lmcancu]

Re: Onkyo receiver/amplifier

Its a pretty old one. TX sv545. Had it for at least 10 years, and it was a hand me down from my brother in law so he had it for a while. I'll try cleaning to see if that fixes it.

[lmcancu]

Re: Onkyo receiver/amplifier

I found something suspicious on the FM/AM daughter card. A component lead was broken. Anyone know what this component is and where I can find a replacement. Could this be the cause?

[Scenic]

Re: Onkyo receiver/amplifier

"L" indicates that it's an inductor/coil..

http://en.wikipedia.org/wiki/Electronic_symbol

[steve2]

Re: Onkyo receiver/amplifier

I tried uploading the manual 3 times, but it keeps failing. L109 (for 120 volt USA and Canada) models Part # NCH-2140 or 231092 (onkyo #). The schematic has it as a 102j which I don't know if is 1000uh? Yes the 102J is 1000uh, 1mh. The J is 5% tolerance.

[Tube_Dude]

Re: Onkyo receiver/amplifier

I tried uploading the manual 3 times, but it keeps failing. L109 (for 120 volt USA and Canada) models Part # NCH-2140 or 231092 (onkyo #). The schematic has it as a 102j which I don't know if is 1000uh? Yes the 102J is 1000uh, 1mh. The J is 5% tolerance.

Measure L110. the value will be the same.

Just to be sure about the problem, short L109, and see if the FM work properly, in both channels.

L109 are just part of the MPX output filter so, shorting it with a wire link doesn't cause any problem.

Cheers

[Scenic]

Re: Onkyo receiver/amplifier

I tried uploading the manual 3 times, but it keeps failing.

there seems to be a filesize bug for .pdf files. the manage attachments thingy says the limit is 9.54MB, but the actual limit is 1.91MB, so any file bigger than that just won't upload.
i've PMed topcat about that a while ago..

[steve2]

Re: Onkyo receiver/amplifier

Thanks Scenic. I put one up earlier , but it was 1.7mb This one is 4mb or so.

[lmcancu]

Re: Onkyo receiver/amplifier

Thanks for the help. I searched for the part but could not find the exact part at mouser or digikey. I found the following parts. Would these work? The dimensions of the original part are about 7.5 mm diameter, and 10 mm long.

http://ca.mouser.com/ProductDetail/F...1HsY9HzTj8k%3d

http://ca.mouser.com/ProductDetail/T...N6NKnHdL2dU%3d

http://search.digikey.com/scripts/Dk...=445-3778-1-ND

Also, I read up on the MPX filter, and understood that it notches out the 19 KHz pilot tone that indicates stereo info so that it doesn't mess up the audio while recording to tape. Is this the only downside to disabling the MPX filter?

[steve2]

Re: Onkyo receiver/amplifier

Not sure if I am seeing right, but how many leads are on the L109? Looks like 2 broken and more still in the board. Is there no way to solder the leads back together?

[lmcancu]

Re: Onkyo receiver/amplifier

There are only 2 leads. I tried soldering it it place, but it did not bond. It seems the broken lead is ripped from the base. I'll try removing it from the board to see if I can reattach the lead to the base.

[lmcancu]

Re: Onkyo receiver/amplifier

it looks like its going to be difficult. My eyes aren't very good anymore! I removed the inductor from the board. The leads are attached to the plastic and then there is a very find wind from the inductor coil on them. For the lead that is broken, it is no longer in the plastic and the inducutor coil is barely next to the platic hole. I would need to figure out a way to attach a lead from an old capacitor or somehting like it to the plastis base, and solder the wind onto it of which there is very little.

[steve2]

Re: Onkyo receiver/amplifier

I am the same with the eyes. I wear a magnifier visor when working small parts. I would try what you said and solder a piece of fine wire to the existing piece to make it long enough to reach the new post.

[lmcancu]

Re: Onkyo receiver/amplifier

Ok, I tried fixing the inductor with no luck. Much too delicate for me! I took Tude_dude's advice and shorted L109 and now both speakers are at the same level. Only catch is that I'm not sure if the Stereo mode is gone now? There is no indication on the display that the FM channel is is Stereo mode, and it seems like both speakers are the same. Anyone know if the display should say Stereo when the FM channel is Stereo? Is this a side effect?

[Tube_Dude]

Re: Onkyo receiver/amplifier

Anyone know if the display should say Stereo when the FM channel is Stereo?

Yes, when the transmission is in stereo, the stereo display must say so.

But the inductor is after the stereo decoder, so without any influence in the stereo operation.

See if the receiver have a switch for stereo mode, many have...

In the pic we can see the inductor L109 have written 183, this means 18 with 3 zeros, so the value is 18 mH or 18000 uH.

[lmcancu]

Re: Onkyo receiver/amplifier

I got the spec from Steve and in the schematic L109 says 102j. 102j is 1 mH with 5%. Are you sure about the 183 markings? Maybe the schematic is out of date?
Also, I'm thinking the inductor is also used for the pilot tone detection as well as removal and makes the stereo detection not work since the inductor is shorted.