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Old 11th Nov 2011, 12:25 pm   #1
lampardlb
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Default Rotel RX-203: working via Headphones but no sound from speakers.

Hi everyone,

I have a Rotel Vintage receiver RX-203, it has very beautiful sound. Yet there is some problem with it. When turned on, it can put very good sound through the headphone plug into my headphone, all the components are working in full orders: amplifier, AM/FM receiver; but no sound at all through the spring terminals to the speakers.

Could anyone please give some advice on how to repair it? I have the owner's manual and service manual which is too large to upload, if you need them, please let me know.

Thank you very much!
lampardlb
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Old 11th Nov 2011, 1:17 pm   #2
Herald1360
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

It sounds like possibly a problem with the switch contacts on the headphone jack. These will cutout the loudspeaker outputs when the plug is inserted. If the contacts stick / weak spring / dirty contacts then this may be the problem.

If you could put up a scan of the output stage area of the circuit diagram, this may help with further suggestions.
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Old 11th Nov 2011, 1:32 pm   #3
lampardlb
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Thank you very much Herald1360 for you reply and also to Peter for his post below.

I tried with headphone unplugged but still no sound output from speakers. I don't know how to remove the wooden cover (I'll try later), but I believe it has been put in a quite clean, dust free environment, so the possibility for dirty contact may not be so high.

A friend suggest that the power amplifier circuit may have something going wrong, for the fact that it's working via headphones proves the pre-amp good. Do you think this is also a possibility?

Cheers
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Old 11th Nov 2011, 1:38 pm   #4
peter_sol
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Also some amps have a switch to select speakers and or phones.
It is worth checking for that.
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Old 11th Nov 2011, 2:00 pm   #5
pichacker
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

I used to have an RX203 a long while ago. (70's) It uses a Sanken SI1020H (I think) hybrid for the final output stage. I guess you'll be lucky to find one of these by now.

The amp drives both speakers and headphones so should be ok unless for some reason it cannot deliver any real power. Have you checked the two fuses on the rear underneath the black plastic cover. This is held by a single screw.

To remove the amp from the wooden case turn it upside down and remove the screws in the bottom. Not sure if they are part of the feet or just with bug square washers. It was nearly 30 years ago.... then slide the innards out through the front.

Could still be the headphone socket even if from a clean environment.

Good luck. Great tuner amp.
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Last edited by pichacker; 11th Nov 2011 at 2:09 pm.
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Old 11th Nov 2011, 2:00 pm   #6
lampardlb
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Sorry Chris, I misunderstood your meaning. The attachment is the diagram of the output part.

Cheers
lampardlb
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Old 11th Nov 2011, 2:09 pm   #7
lampardlb
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Hi pichacker:
Thank you for your reply. Yes, the fuses are OK and output via the headphone jack is 100% normal. Does this necessarily mean the output stage is OK? If so, it may be the switch between speaker and headphone docks...

Cheers
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Old 11th Nov 2011, 2:16 pm   #8
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Well, I've checked the diagram, it looks like the speakers use the same line with headphones, so it may be the switch and contact between the headphone and speaker docks... I'll check it now, thank you everyone!
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Old 11th Nov 2011, 2:48 pm   #9
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

I take it there is no sound at all out the speakers from BOTH channels? I'd defo take a look at the headphone socket before going any further.

You could try connecting the speaker positive directly to each output fuse as these are before the headphone jack. I also take it the speaker -ve is grounded ok as this is also common to both channels.
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Old 11th Nov 2011, 2:55 pm   #10
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Defo a brilliant idea to connect positive to the fuses, I'll try that, thanks pichacker!
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Old 11th Nov 2011, 4:46 pm   #11
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Fixed!!As some of you pointed out-it's the dirty switch between speaker and headphone that caused the problem. Thank you all very much for your help!

Cheers
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Old 11th Nov 2011, 4:48 pm   #12
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.



Result!
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Old 12th Nov 2011, 11:23 am   #13
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Glad to hear it is working.

I had similar symptoms with a Rotel or Marantz amp. The fault eluded me until I realised that the speaker fuse holder was making poor contact with the fuses.
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Old 23rd Nov 2011, 10:02 am   #14
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Default Re: Rotel RX-203: working via Headphones but no sound from speakers.

Glad to hear the problem's been sorted. The most baffling faults are often caused by simple means. I have an RX403 receiver myself which functions perfectly although I became concerned by some intermittent distortion and varying output in the left channel recently.

It turned out the problem was simply due to a noisy tape monitor switch!

Cheers,
Brian
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