Roberts Stream 83i ... Kaput! Repairable?

FM receiver discussion
Post Reply
User avatar
John Faulkner, Skegness
Posts: 5380
Joined: 19 Sep 2014 15:55
Location: Skegness, Lincolnshire. JO03dd
Contact:

Roberts Stream 83i ... Kaput! Repairable?

Post by John Faulkner, Skegness » 22 Apr 2017 19:59

Silly me accidentally plugged my 19V laptop supply into the 83i. It worked for a while but then I noticed there was no sound. The two plugs were identical in appearance and lying right next to each other on the floor. I happened to pick up the wrong one without realising.

So, the radio appears to work 100% still, apart from the lack of audio.

My guess is that I have blown the output stage of the audio amplifier.

The question is, how do I fix this? I remember doing a modification on an old radio which had a similar problem years ago. I simply tapped into the volume control variable resistor and took it to the headphone socket outlet where I could hook that up to a regular audio amplifier. It worked perfectly!

But how do I know exactly what's happened here? There is the slightest bit of audio coming from the internal loudspeaker if I crank it up fully. Same with the headphone output and the phono outputs. Whatever has happened affects all three things. Audio output transistors?

If this is the case, would my AF variable resistor modification work in this instance?

Thanks.

User avatar
eastangliauk
Posts: 382
Joined: 09 Oct 2014 14:16
Location: Clacton On Sea
Contact:

Re: Roberts Stream 83i ... Kaput! Repairable?

Post by eastangliauk » 22 Apr 2017 20:51

I also have a pure evoke flow like this the speaker does not work can only get audio on the stereo out not sure what happened to it.
Radios Tecsun PL398MP + PL-660 & JVC KD-G632 - Blaupunkt BPR-3 DAB+

Andrew Webster,Wigan
Posts: 2189
Joined: 18 Sep 2014 16:03
Location: Wigan Northwest England
Contact:

Re: Roberts Stream 83i ... Kaput! Repairable?

Post by Andrew Webster,Wigan » 22 Apr 2017 22:26

I assume the supply should be 12 v so I would expect with 19 v the output transistors/chips to fail the rest of the circuit/proccessor will run off 5 v so the regulator has done a good job.
The fact you have weak audio tells me that the radio is working ok so it should be possible to tap into the audio feed to the output chips but it does depend on how the chips have failed.

Anyway if you can John if you can open it up and trace the speaker wires and tracks to the output chips and give me the chip Number and I can look it up.
There's Buckleys chance on a circuit diagram for Dab radio's or most things modern.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

User avatar
John Faulkner, Skegness
Posts: 5380
Joined: 19 Sep 2014 15:55
Location: Skegness, Lincolnshire. JO03dd
Contact:

Re: Roberts Stream 83i ... Kaput! Repairable?

Post by John Faulkner, Skegness » 23 Apr 2017 12:47

Thanks Andy.

I'll try to do that today, but so much to do here. Might be going away tomorrow and lots to do to catch up. Driving a few hundred miles to take my wife to see her new boyfriend. Life just gets weirder! So still not exactly with it here, but struggling forward in whatever direction I can.

The radio works 100% with RDS, DAB, etc. It's just the audio which is the problem.

Thanks EAUK. The stereo phono out has the same problem on my Stream 83i. All 'outputs' including headphones are 90%+ reduced in level. I feel confident there will be a fix for this, but I am surprised to learn that engineering manuals aren't easy to come by.

Andrew Webster,Wigan
Posts: 2189
Joined: 18 Sep 2014 16:03
Location: Wigan Northwest England
Contact:

Re: Roberts Stream 83i ... Kaput! Repairable?

Post by Andrew Webster,Wigan » 23 Apr 2017 15:16

DAB manufactures obviously have service manuals but they won't release them as they want you to either let them repair it or buy another.


Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

User avatar
John Faulkner, Skegness
Posts: 5380
Joined: 19 Sep 2014 15:55
Location: Skegness, Lincolnshire. JO03dd
Contact:

Re: Roberts Stream 83i ... Kaput! Repairable?

Post by John Faulkner, Skegness » 23 Apr 2017 21:08

Well, they need to make their £millions.

I won't be able to check the internals of the radio for at least another week. I'm disappearing for a few days.

Post Reply

Return to “Receivers”