Marconiphone 4633 (actually a 4366) Speaker problem - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Edward Huggins · 21st Jun 2018, 7:41 am

Can we be clear in that when you tsted the RH speaker with a 1.5V battey as suggested, you got no cone movement/scratching sound? If that's correct, double check the speaker's voicecoil for continuity.

dseymo1 · 21st Jun 2018, 7:48 am

Looks as though there's a problem with the RH. amplifier, which might well have killed the speaker. Don't sub the other speaker at this stage in that case!

crackle · 21st Jun 2018, 2:56 pm

It looks like this chassis has Callins capacitors on it, if they are going short circuit then who knows what may have happened.

Mike

dubsessive · 21st Jun 2018, 4:12 pm

That doesn't sound good!

dubsessive · 21st Jun 2018, 4:24 pm

Just to be sure I got no sound whatsoever with the speaker no movement no scratching noises. I even tried it with a 9v battery.

Grubhead · 21st Jun 2018, 8:32 pm

Yes it does use Callins or Lorlin electrolytic capacitors.
The speakers are 15 ohms. If one of them is faulty it might have taken out the push pull output stage VT20 and VT18.
Transistors OP9A - which are R2322 or BRC6109
OP9B - which are R2322 or BRC5296

crackle · 22nd Jun 2018, 6:14 am

Quote:

Originally Posted by Grubhead

Yes it does use Callins or Lorlin electrolytic capacitors.
The speakers are 15 ohms. If one of them is faulty it might have taken out the push pull output stage VT20 and VT18.
Transistors OP9A - which are R2322 or BRC6109
OP9B - which are R2322 or BRC5296

Speakers dont normally fuse, if one of the speakers is faulty then there is a reason, like a serious fault on the chassis. Replacing the speaker will probably result in another blown speaker. This repair may need to be looked at more seriously by someone with experience.

Mike

Grubhead · 22nd Jun 2018, 2:52 pm

A child poking something in the grid slots of the cabinet could damage the speaker. Things like grids and vents fascinate young children.
I remember running a pencil up and down the back of TV back cover because it made a very musical sound. Didn't do any damage to it though.
And my nephew poked my tweeters out with his fingers! I told his dad. "yes he did the same to mine" was his reply!

Edward Huggins · 22nd Jun 2018, 3:56 pm

Based on the OP's latest Post, it does look like the speaker has (most unusually) failed.

It is not quite so easy to go and buy a 15 ohm 8" x 5" unit these days. Before the search for one starts, that amplifier channel needs a good going over. If it's an economic repair, then think about another speaker. The OP might seek hands-on help, if needed, via this Forum.

Grubhead · 24th Jun 2018, 1:09 am

I think it would cheaper and simpler to replace both speakers with other 15 ohm types. They don't have to be the same shape as the originals. It's not as though they are on display. He will just have to either remove the mounts for the old speakers. Then use screws or clamps to mount the new ones.

21st Jun 2018, 7:41 am	#21
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Marconiphone 4633 (actually a 4366) Speaker problem Can we be clear in that when you tsted the RH speaker with a 1.5V battey as suggested, you got no cone movement/scratching sound? If that's correct, double check the speaker's voicecoil for continuity. __________________ Edward.

21st Jun 2018, 7:48 am	#22
dseymo1 Retired Dormant Member Join Date: Dec 2007 Location: Shropshire, UK. Posts: 3,051	Re: Marconiphone 4633 (actually a 4366) Speaker problem Looks as though there's a problem with the RH. amplifier, which might well have killed the speaker. Don't sub the other speaker at this stage in that case!

21st Jun 2018, 2:56 pm	#23
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Marconiphone 4633 (actually a 4366) Speaker problem It looks like this chassis has Callins capacitors on it, if they are going short circuit then who knows what may have happened. Mike Attached Thumbnails

21st Jun 2018, 4:12 pm	#24
dubsessive Retired Dormant Member Join Date: Jun 2018 Location: Cambridgeshire, UK. Posts: 8	Re: Marconiphone 4633 (actually a 4366) Speaker problem That doesn't sound good!

21st Jun 2018, 4:24 pm	#25
dubsessive Retired Dormant Member Join Date: Jun 2018 Location: Cambridgeshire, UK. Posts: 8	Re: Marconiphone 4633 (actually a 4366) Speaker problem Just to be sure I got no sound whatsoever with the speaker no movement no scratching noises. I even tried it with a 9v battery.

21st Jun 2018, 8:32 pm	#26
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Marconiphone 4633 (actually a 4366) Speaker problem Yes it does use Callins or Lorlin electrolytic capacitors. The speakers are 15 ohms. If one of them is faulty it might have taken out the push pull output stage VT20 and VT18. Transistors OP9A - which are R2322 or BRC6109 OP9B - which are R2322 or BRC5296

22nd Jun 2018, 2:52 pm	#28
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Marconiphone 4633 (actually a 4366) Speaker problem A child poking something in the grid slots of the cabinet could damage the speaker. Things like grids and vents fascinate young children. I remember running a pencil up and down the back of TV back cover because it made a very musical sound. Didn't do any damage to it though. And my nephew poked my tweeters out with his fingers! I told his dad. "yes he did the same to mine" was his reply!

22nd Jun 2018, 3:56 pm	#29
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Marconiphone 4633 (actually a 4366) Speaker problem Based on the OP's latest Post, it does look like the speaker has (most unusually) failed. It is not quite so easy to go and buy a 15 ohm 8" x 5" unit these days. Before the search for one starts, that amplifier channel needs a good going over. If it's an economic repair, then think about another speaker. The OP might seek hands-on help, if needed, via this Forum. __________________ Edward.

24th Jun 2018, 1:09 am	#30
Grubhead Heptode Join Date: Dec 2016 Location: Sheffield, South Yorkshire, UK. Posts: 539	Re: Marconiphone 4633 (actually a 4366) Speaker problem I think it would cheaper and simpler to replace both speakers with other 15 ohm types. They don't have to be the same shape as the originals. It's not as though they are on display. He will just have to either remove the mounts for the old speakers. Then use screws or clamps to mount the new ones.