Marconi 4542 (Canada) - UK Vintage Radio Repair and Restoration Discussion Forum

skyninja · 24th Sep 2022, 4:17 pm

No sound from record player. FM and AM bands play fine so do not suspect the amplifier. Checked all the wiring to the phono inputs on the main board. I will be checking switch contacts that selects FM/AM/Phono.

Can a cartridge go bad?

I believe it may be the cartridge. It is a ful-fi TC8S (M) with a LP/78 needle that can flip over. I can here the needle in the record is picking up sound but I do not know if it is converting to electrical signal. The cartridge is connected directly to a 4 cables of which 3 are in use.

Can I pull the connectors off the cartridge or are they part of the assembly?

If it is the cartridge what is a suitable replacement?

From the limited circuit diagrams I was able to find, the phono input goes direct to the selector switch so I do not believe there is a pre-amp.

Thanks
Stephen

Techman · 24th Sep 2022, 5:41 pm

Quote:

Originally Posted by skyninja

No sound from record player.

Can a cartridge go bad?

It is a ful-fi TC8S (M) with a LP/78 needle that can flip over.

That's all you need to know. It's pretty much guaranteed to be duff!

Do a 'buzz test' to check the amplifier (look it up on here if you're unsure).

Should be an easy fix as the old cartridge is the 'M' (medium output) type and modern replacements are available at a reasonable cost - the Chinese ceramic replacements on ebay are recommended.

Techman · 24th Sep 2022, 6:12 pm

One important point that I forgot to mention is that you'll need to budget for a stylus pressure gauge as the replacement cartridge is going to likely be lighter than the original, so you'll need to reset the tracking weight of the tone arm.

Another thing to remember is never solder directly to the cartridge pins as heat will destroy a cartridge in seconds!

Also, your old cartridge was 'mono' only with a two pin output and a new replacement will have four pins, so you'll need to link the two channels together.

Even if your old cartridge was still working, it would damage any stereo pressings - that's basically any records pressed after 1970.

Techman · 24th Sep 2022, 6:36 pm

Quote:

Originally Posted by skyninja

TC8S. The cartridge is connected directly to a 4 cables of which 3 are in use.

Can I pull the connectors off the cartridge or are they part of the assembly?

I also forgot that although your cartridge is the 'S' for stereo version of this old design, it still uses the 'mechanics' of the mono version and will still cause damage to valuable stereo records - fine if you're not too concerned about your records and just want to play them anyway.

You can pull the connectors off, but remember what I said about keeping the soldering iron away from them when they're on a cartridge - at least you've got three out of the four wires that you'll need to connect to a replacement cartridge.

I think that you can still buy a TC8S (at a price), but just keep in mind its limitations regarding modern records.

skyninja · 24th Sep 2022, 11:48 pm

Techman, many thanks for all the info, exactly what I was looking for.

Stephen

Techman · 25th Sep 2022, 12:13 pm

Glad it was helpful.

Remember to check out doing that 'buzz test' if you haven't already done so. Full volume setting and touch the two 'signal' wires individually with an insulated screwdriver blade where they connect to the cartridge - there should be a 'loud' buzz from each speaker. This just rules out anything that might be wrong in the signal path from the cartridge, even though this is fairly unlikely, seeing as the radio section is working fine.

24th Sep 2022, 4:17 pm	#1
skyninja Diode Join Date: Sep 2022 Location: Katy, Texas, USA Posts: 2	Marconi 4542 (Canada) No sound from record player. FM and AM bands play fine so do not suspect the amplifier. Checked all the wiring to the phono inputs on the main board. I will be checking switch contacts that selects FM/AM/Phono. Can a cartridge go bad? I believe it may be the cartridge. It is a ful-fi TC8S (M) with a LP/78 needle that can flip over. I can here the needle in the record is picking up sound but I do not know if it is converting to electrical signal. The cartridge is connected directly to a 4 cables of which 3 are in use. Can I pull the connectors off the cartridge or are they part of the assembly? If it is the cartridge what is a suitable replacement? From the limited circuit diagrams I was able to find, the phono input goes direct to the selector switch so I do not believe there is a pre-amp. Thanks Stephen

24th Sep 2022, 6:12 pm	#3
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Marconi 4542 (Canada) One important point that I forgot to mention is that you'll need to budget for a stylus pressure gauge as the replacement cartridge is going to likely be lighter than the original, so you'll need to reset the tracking weight of the tone arm. Another thing to remember is never solder directly to the cartridge pins as heat will destroy a cartridge in seconds! Also, your old cartridge was 'mono' only with a two pin output and a new replacement will have four pins, so you'll need to link the two channels together. Even if your old cartridge was still working, it would damage any stereo pressings - that's basically any records pressed after 1970.

24th Sep 2022, 11:48 pm	#5
skyninja Diode Join Date: Sep 2022 Location: Katy, Texas, USA Posts: 2	Re: Marconi 4542 (Canada) Techman, many thanks for all the info, exactly what I was looking for. Stephen

25th Sep 2022, 12:13 pm	#6
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Marconi 4542 (Canada) Glad it was helpful. Remember to check out doing that 'buzz test' if you haven't already done so. Full volume setting and touch the two 'signal' wires individually with an insulated screwdriver blade where they connect to the cartridge - there should be a 'loud' buzz from each speaker. This just rules out anything that might be wrong in the signal path from the cartridge, even though this is fairly unlikely, seeing as the radio section is working fine.