Defiant RGSH 853 AC Radio Gramophone buzzing - UK Vintage Radio Repair and Restoration Discussion Forum

Quotient · 5th Jan 2020, 5:42 pm

Hi all.
A friend of mine has an RGSH 853 AC Radio Gramaphone which has an ever increasing buzzing noise from the speaker. It has been working fine up until a few weeks ago. She had unplugged it and moved to a new socket, it then started buzzing from the speaker. She tried plugging back into the old socket to no avail, the plug top has been checked and confirmed electrically safe. Although it still has old single insulated lead.
The unit has not had any jolts bangs drops or any other mishaps.

We removed the back and noticed one valve (Mazda 6F15) was not lighting. We managed to source a new one and change it in the hope this was the problem. The new valve lit up like the others, however the sound came back.
I have searched the tinterwebz regarding this problem but to no avail. Eventually I found myself here and although this model is mentioned. It was not for this scenario.
Is there anyone here who may understand my description and or may be able to diagnose or point me to somewhere that can. I am confident enough to understand/follow instructions and do the repairs myself if doable. I have included some pictures. I have also made a small video but was unable to upload. I can send this privately if required.

Many thanks in advance for any help.

Q

Station X · 5th Jan 2020, 5:54 pm

Service info available here:-

https://www.service-data.com/section.php/1772/1/rgsh756

You'll get plenty of replies shortly telling you which components to replace.

PJL · 5th Jan 2020, 6:26 pm

The radio will need a full service including replacement of some of the electronic parts. To do this work yourself you will need a lot of patience and some basic tools like a soldering iron and solder and a digital multimeter. Have you any electronics experience?

The service sheet above does not appear to cover this model. It is a 4 valve + rectifier AC only set based on the MSH453 table top.

Station X · 5th Jan 2020, 6:59 pm

You're right. Wrong service sheet. The smoothing capacitors must be under the chassis.

Quotient · 6th Jan 2020, 12:49 am

Yes I do have the above mentioned tools. A very small amount of electronics experience. I can recognise most components. Will also make sure I understand what and why I'm doing a set thing before undertake the task. Safety at the forefront

Thanks again guys.��

Station X · 6th Jan 2020, 11:48 am

I you post a picture of the UNDERSIDE of the chassis we'll be able to tell you which components should be replaced first to get rid of the hum and prevent any future damage.

5th Jan 2020, 5:42 pm	#1
Quotient Diode Join Date: Dec 2019 Location: Angus, Scotland, UK. Posts: 2	Defiant RGSH 853 AC Radio Gramophone buzzing Hi all. A friend of mine has an RGSH 853 AC Radio Gramaphone which has an ever increasing buzzing noise from the speaker. It has been working fine up until a few weeks ago. She had unplugged it and moved to a new socket, it then started buzzing from the speaker. She tried plugging back into the old socket to no avail, the plug top has been checked and confirmed electrically safe. Although it still has old single insulated lead. The unit has not had any jolts bangs drops or any other mishaps. We removed the back and noticed one valve (Mazda 6F15) was not lighting. We managed to source a new one and change it in the hope this was the problem. The new valve lit up like the others, however the sound came back. I have searched the tinterwebz regarding this problem but to no avail. Eventually I found myself here and although this model is mentioned. It was not for this scenario. Is there anyone here who may understand my description and or may be able to diagnose or point me to somewhere that can. I am confident enough to understand/follow instructions and do the repairs myself if doable. I have included some pictures. I have also made a small video but was unable to upload. I can send this privately if required. Many thanks in advance for any help. Q Attached Thumbnails

5th Jan 2020, 5:54 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Defiant RGSH 853 AC Radio Gramaphone buzzing Service info available here:- https://www.service-data.com/section.php/1772/1/rgsh756 You'll get plenty of replies shortly telling you which components to replace. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

5th Jan 2020, 6:26 pm	#3
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Defiant RGSH 853 AC Radio Gramaphone buzzing The radio will need a full service including replacement of some of the electronic parts. To do this work yourself you will need a lot of patience and some basic tools like a soldering iron and solder and a digital multimeter. Have you any electronics experience? The service sheet above does not appear to cover this model. It is a 4 valve + rectifier AC only set based on the MSH453 table top. Last edited by PJL; 5th Jan 2020 at 6:44 pm.

5th Jan 2020, 6:59 pm	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Defiant RGSH 853 AC Radio Gramaphone buzzing You're right. Wrong service sheet. The smoothing capacitors must be under the chassis. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

6th Jan 2020, 12:49 am	#5
Quotient Diode Join Date: Dec 2019 Location: Angus, Scotland, UK. Posts: 2	Re: Defiant RGSH 853 AC Radio Gramaphone buzzing Yes I do have the above mentioned tools. A very small amount of electronics experience. I can recognise most components. Will also make sure I understand what and why I'm doing a set thing before undertake the task. Safety at the forefront Thanks again guys.��

6th Jan 2020, 11:48 am	#6
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Defiant RGSH 853 AC Radio Gramophone buzzing I you post a picture of the UNDERSIDE of the chassis we'll be able to tell you which components should be replaced first to get rid of the hum and prevent any future damage. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.