Civic R4900. No sound from main speaker. - UK Vintage Radio Repair and Restoration Discussion Forum

Jack_Davis · 2nd Feb 2019, 5:23 pm

I have a Civic R4900 Valve radio from 1967 that works and can find some signals however there are two speakers located inside the chassis. One small one big, the small one outputs some sound but not much but the bigger speaker on the right produces no sound at all. Has anyone had this problem before and can offer any help all appreciated. thank you

Edward Huggins · 2nd Feb 2019, 6:37 pm

The small speaker is called a Tweeter and will only give you treble sounds above about 1.5kHz. That large beefy speaker will be a full range unit. Check the connections to the speaker and the flexible connections to the cone. Test for continuity with a Multimeter. If you don't have one, make a simple continuity Tester with a battery and some wire which should move the cone and make a scratchy sound. Let us know how you get on. .

Jack_Davis · 2nd Feb 2019, 7:11 pm

Thanks for your input. Will it matter for positive or negative on the speaker and is any battery ok

Jack_Davis · 2nd Feb 2019, 7:30 pm

Yep there was definitely some popping and buzz coming out of the speaker so are we looking at some sort of connection issue

PJL · 2nd Feb 2019, 8:57 pm

Could be the speaker coil rubbing. You need to check the cone moves freely.

Jack_Davis · 2nd Feb 2019, 9:06 pm

Yeah the cone is definitely moving up and down

cathoderay57 · 2nd Feb 2019, 9:54 pm

Hi Jack, it's hard to see from the pictures but it looks like there is an extension speaker socket at the lower right side of the chassis. It might have switched contacts that could be stuck open isolating the internal speaker. Trace the wiring back from the internal speaker and see if it goes via a switched socket. Cheers, Jerry

ms660 · 2nd Feb 2019, 10:04 pm

There's a schaltplan available on the web.

Lawrence.

Jack_Davis · 2nd Feb 2019, 10:11 pm

Quote:

Originally Posted by cathoderay57

Hi Jack, it's hard to see from the pictures but it looks like there is an extension speaker socket at the lower right side of the chassis. It might have switched contacts that could be stuck open isolating the internal speaker. Trace the wiring back from the internal speaker and see if it goes via a switched socket. Cheers, Jerry

It is soldered to a point that is connected by a wire to the speaker input.

Nuvistor · 2nd Feb 2019, 10:22 pm

That white plastic with 3 sockets I think is for an external speaker, is there an internal switch in that assembly to disconnect the internal speaker.
The circuit shows the main speaker switched but not the tweeter.

Jack_Davis · 2nd Feb 2019, 10:37 pm

No doesn't look like it. The main speaker goes to the solder joint mentioned previously and under to what looks to be a long blue component. Possibley resistor

Nuvistor · 2nd Feb 2019, 10:43 pm

Link to a thread on radios-tv, the fault was bad soldering on the sound output transformer, could it be the same fault on your radio.
https://www.radios-tv.co.uk/communit...c-r4900-radio/

Jack_Davis · 2nd Feb 2019, 10:48 pm

It could be but I'm a bit of a amature when it comes to recognising this I can solder but I will probably need help knowing where to do this

Nuvistor · 2nd Feb 2019, 11:13 pm

The sound output transformer is shown by the red line, visually check for bad connections.

Jack_Davis · 2nd Feb 2019, 11:49 pm

Personally I can't see anything too bad. Could dust block anything because I have yet to give it a proper clean?

Jack_Davis · 3rd Feb 2019, 12:04 am

Here is where the two wires connect to from the speaker. One goes into what seems to be some sort of output box the other travels under the board and into that small blue component. This component might be dead as is has a black dot on one side which looks like a hole but not sure

Nuvistor · 3rd Feb 2019, 1:44 am

Dust would not normally cause the problem unless it was in a switch or plug and socket, its usually tarnish in those rather than dust though.

You are going to have to trace the wiring out and see if you can find a break, a multimeter would help if you have one.

Edward Huggins · 4th Feb 2019, 2:04 pm

Do you have another speaker to test with, say from a stereo system? Just connect it to the 2 soldered tags at the top of the oval speaker.

Station X · 4th Feb 2019, 2:30 pm

Post #4 and #6 suggest that the speaker is OK.

Jack_Davis · 4th Feb 2019, 11:02 pm

I think I have found the problem. One of the speaker wire was connected to this blue diode diode of some sorts marked with 150kf and a "S" symbol on it and in the board marked C69 can anyone find out what this is

2nd Feb 2019, 5:23 pm	#1
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Civic R4900. No sound from main speaker. I have a Civic R4900 Valve radio from 1967 that works and can find some signals however there are two speakers located inside the chassis. One small one big, the small one outputs some sound but not much but the bigger speaker on the right produces no sound at all. Has anyone had this problem before and can offer any help all appreciated. thank you Attached Thumbnails

2nd Feb 2019, 6:37 pm	#2
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,338	Re: No sound from main speaker in valve radio The small speaker is called a Tweeter and will only give you treble sounds above about 1.5kHz. That large beefy speaker will be a full range unit. Check the connections to the speaker and the flexible connections to the cone. Test for continuity with a Multimeter. If you don't have one, make a simple continuity Tester with a battery and some wire which should move the cone and make a scratchy sound. Let us know how you get on. . __________________ Edward.

2nd Feb 2019, 7:11 pm	#3
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio Thanks for your input. Will it matter for positive or negative on the speaker and is any battery ok

2nd Feb 2019, 8:57 pm	#5
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: No sound from main speaker in valve radio Could be the speaker coil rubbing. You need to check the cone moves freely.

2nd Feb 2019, 9:54 pm	#7
cathoderay57 Nonode Join Date: Oct 2017 Location: Bristol, UK. Posts: 2,387	Re: No sound from main speaker in valve radio Hi Jack, it's hard to see from the pictures but it looks like there is an extension speaker socket at the lower right side of the chassis. It might have switched contacts that could be stuck open isolating the internal speaker. Trace the wiring back from the internal speaker and see if it goes via a switched socket. Cheers, Jerry

2nd Feb 2019, 7:30 pm	#4
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio Yep there was definitely some popping and buzz coming out of the speaker so are we looking at some sort of connection issue

2nd Feb 2019, 9:06 pm	#6
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio Yeah the cone is definitely moving up and down

2nd Feb 2019, 10:04 pm	#8
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: No sound from main speaker in valve radio There's a schaltplan available on the web. Lawrence.

2nd Feb 2019, 10:22 pm	#10
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: No sound from main speaker in valve radio That white plastic with 3 sockets I think is for an external speaker, is there an internal switch in that assembly to disconnect the internal speaker. The circuit shows the main speaker switched but not the tweeter. __________________ Frank

2nd Feb 2019, 10:37 pm	#11
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio No doesn't look like it. The main speaker goes to the solder joint mentioned previously and under to what looks to be a long blue component. Possibley resistor

2nd Feb 2019, 10:43 pm	#12
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: No sound from main speaker in valve radio Link to a thread on radios-tv, the fault was bad soldering on the sound output transformer, could it be the same fault on your radio. https://www.radios-tv.co.uk/communit...c-r4900-radio/ __________________ Frank

2nd Feb 2019, 10:48 pm	#13
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio It could be but I'm a bit of a amature when it comes to recognising this I can solder but I will probably need help knowing where to do this

2nd Feb 2019, 11:13 pm	#14
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: No sound from main speaker in valve radio The sound output transformer is shown by the red line, visually check for bad connections. Attached Thumbnails __________________ Frank

2nd Feb 2019, 11:49 pm	#15
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio Personally I can't see anything too bad. Could dust block anything because I have yet to give it a proper clean?

3rd Feb 2019, 12:04 am	#16
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio Here is where the two wires connect to from the speaker. One goes into what seems to be some sort of output box the other travels under the board and into that small blue component. This component might be dead as is has a black dot on one side which looks like a hole but not sure Attached Thumbnails

3rd Feb 2019, 1:44 am	#17
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: No sound from main speaker in valve radio Dust would not normally cause the problem unless it was in a switch or plug and socket, its usually tarnish in those rather than dust though. You are going to have to trace the wiring out and see if you can find a break, a multimeter would help if you have one. __________________ Frank

4th Feb 2019, 2:04 pm	#18
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,338	Re: No sound from main speaker in valve radio Do you have another speaker to test with, say from a stereo system? Just connect it to the 2 soldered tags at the top of the oval speaker. __________________ Edward.

4th Feb 2019, 2:30 pm	#19
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: No sound from main speaker in valve radio Post #4 and #6 suggest that the speaker is OK. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

4th Feb 2019, 11:02 pm	#20
Jack_Davis Triode Join Date: Jan 2019 Location: Bristol, UK. Posts: 25	Re: No sound from main speaker in valve radio I think I have found the problem. One of the speaker wire was connected to this blue diode diode of some sorts marked with 150kf and a "S" symbol on it and in the board marked C69 can anyone find out what this is Attached Thumbnails