Thorn Ultra 6339 - UK Vintage Radio Repair and Restoration Discussion Forum

LucymFray · 18th May 2018, 10:04 am

Hi, I’ve recently acquired a Thorn Ultra 6339 and have managed to unseize the deck which was solid with grease, with the auto changer working fine. The volume on it is even better than I first thought it would be - so loud!

Unfortunately, the cartridge is being held in by sellotape and the point of both sides of the needle have been snapped off, so I’m here to see if anyone knows what cartridge is best to replace it with? It is currently a Sonotone 3509. My dad decided he’d test if it was still wired up okay so tested it on an old battered single, and the song came through even without a needle, and at the right speed - from what we could hear.

Also when you stop the deck or when it has got to the end, there is an almighty bang sound from the speakers (I presume) even at low volume. What would be the cause of this and how do I go about fixing it? Dad thinks it’s just dirt in and around the speakers and wires.

Thanks,
Lucy

dazzlevision · 18th May 2018, 11:16 am

The Ultra 6339 is, judging from the model number, a mid-60s stereo radiogram.

The loud noise you describe could be due to the electrical switch contacts on the underside of the record deck opening when the deck goes back into “stop” mode and the motor stops turning. It may be its contacts are dirty or pitted, causing a bigger arc when they open than usual, which gets into the amplifier and is then heard through the speakers. The only other likely option I can think of is that the acoustic energy that is generated when the deck switches off is being mechanically coupled into the pickup cartridge somehow.

There may be an arc suppression capacitor fitted across the deck switch and it might be faulty or missing.

Edward Huggins · 18th May 2018, 11:23 am

The bang you hear will have nothing to do with dirt. It is liable to be an electrical arc caused when the record player sitches off. Some decks use a "switch click suppressor" to cure this. I would not worrry about this right now. If your cartridge is working, and these are now quite expensive (£35-40), why don't you just buy a replacement stylus for your Sonotone 3509? These are readily available from The Stylus Lady, Mantra Audio, Musonic et al. As to the cartridge being held in by Sellotape, this is a very bad idea. In time and especially with high ambient temperatures, this will weaken and sag. As a temporary measure, use can BluTak, but again over time this will sag/go out of alignment and you need to be able to fit it into its optimum position within the tone arm head. Make sure the stylus is vertical from the front and that the cartridge is fitted as close as possible to the front end of the inside of the head. Check with the above suppliers for a mount (usually plastic) for your cartridge.

LucymFray · 18th May 2018, 8:44 pm

What stylus should I get, because I have found both an LP/78 or LP/LP. The original is ASS78/LPS - really unsure as to what’s best.

Thanks for the help so far - been reassuring and very helpful!

Audio1950 · 19th May 2018, 4:39 pm

Quote:

Originally Posted by LucymFray

What stylus should I get, because I have found both an LP/78 or LP/LP.

The LP/78 version has a point for vinyl records (LP's and singles), and another point for old shellac 78s. If you don't have any 78s, then get the LP/LP version, which has two points for modern vinyl records, so you'll get double the usage time.

18th May 2018, 10:04 am	#1
LucymFray Diode Join Date: May 2016 Location: Falkirk, Stirlingshire, Scotland, UK. Posts: 7	Thorn Ultra 6339 Hi, I’ve recently acquired a Thorn Ultra 6339 and have managed to unseize the deck which was solid with grease, with the auto changer working fine. The volume on it is even better than I first thought it would be - so loud! Unfortunately, the cartridge is being held in by sellotape and the point of both sides of the needle have been snapped off, so I’m here to see if anyone knows what cartridge is best to replace it with? It is currently a Sonotone 3509. My dad decided he’d test if it was still wired up okay so tested it on an old battered single, and the song came through even without a needle, and at the right speed - from what we could hear. Also when you stop the deck or when it has got to the end, there is an almighty bang sound from the speakers (I presume) even at low volume. What would be the cause of this and how do I go about fixing it? Dad thinks it’s just dirt in and around the speakers and wires. Thanks, Lucy

18th May 2018, 11:16 am	#2
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,611	Re: Thorn Ultra 6339 The Ultra 6339 is, judging from the model number, a mid-60s stereo radiogram. The loud noise you describe could be due to the electrical switch contacts on the underside of the record deck opening when the deck goes back into “stop” mode and the motor stops turning. It may be its contacts are dirty or pitted, causing a bigger arc when they open than usual, which gets into the amplifier and is then heard through the speakers. The only other likely option I can think of is that the acoustic energy that is generated when the deck switches off is being mechanically coupled into the pickup cartridge somehow. There may be an arc suppression capacitor fitted across the deck switch and it might be faulty or missing.

18th May 2018, 11:23 am	#3
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Thorn Ultra 6339 The bang you hear will have nothing to do with dirt. It is liable to be an electrical arc caused when the record player sitches off. Some decks use a "switch click suppressor" to cure this. I would not worrry about this right now. If your cartridge is working, and these are now quite expensive (£35-40), why don't you just buy a replacement stylus for your Sonotone 3509? These are readily available from The Stylus Lady, Mantra Audio, Musonic et al. As to the cartridge being held in by Sellotape, this is a very bad idea. In time and especially with high ambient temperatures, this will weaken and sag. As a temporary measure, use can BluTak, but again over time this will sag/go out of alignment and you need to be able to fit it into its optimum position within the tone arm head. Make sure the stylus is vertical from the front and that the cartridge is fitted as close as possible to the front end of the inside of the head. Check with the above suppliers for a mount (usually plastic) for your cartridge. __________________ Edward.

18th May 2018, 8:44 pm	#4
LucymFray Diode Join Date: May 2016 Location: Falkirk, Stirlingshire, Scotland, UK. Posts: 7	Re: Thorn Ultra 6339 What stylus should I get, because I have found both an LP/78 or LP/LP. The original is ASS78/LPS - really unsure as to what’s best. Thanks for the help so far - been reassuring and very helpful!