Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind - UK Vintage Radio Repair and Restoration Discussion Forum

Chris55000 · 15th May 2017, 12:07 am

Hi!

I tried my Marconiphone 4238 again after having been cajoied into household repairs at my friend's place where I'm now living, and when I tried a number of American 1800' "Concertape' brand tapes on them I found rewind very slow to the point of being almost having to turn the spool with my finger!

Also, there's rather a lot of very rough-sounding squeaking whenever I try these tapes (they have a dark brown/black finish on the non-magnetic side and they are not paper-based, by the way), and another strange snag is that whenever the machine has been running half-an-hour or more, something starts to make a horrendous clattering noise that instantly stops if I turn the machine up or round!

I have both the DC43 Deck and the Amplifier S.M.'s, other Members have commented on the build and running-quality of these decks, it's just like my luck to get one of the yukky specimens!

Suggestions please?

(I have to confess I'll gladly plough thro' a multi-valve, transistor or IC-based panel to the smallest minuitae to locate an obscure fault but mechanics and me don't agree with each other, even when I've got a full exploded diagram in front of me!)

Chris Williams

ricard · 15th May 2017, 5:47 am

I would think these tapes would be susceptible to sticky shed syndrome, not to mention that it seems they are back coated, which is never suitable for a machine with pressure pads, which I believe the 4238 has. If nothing else, the pads clog up with dust from the back coating.

If it's the Concertape I'm thinking of, it's the nasty stuff that was sold cheaply under all sorts of brand names in the 1970s, spooled on black reels with 6 holes, and MADE IN U.S.A. embossed along the rim.

Found this video of someone demonstrating the sticky shed properties, as well as forcibly demonstrating what the person in question thought should be done with these tapes at the end of the video!

https://www.youtube.com/watch?v=Hl11QHQTuD0

dazzlevision · 15th May 2017, 8:11 am

Hello,

The drive to the take up and supply turntables on the DC43 deck, is by moveable idler wheels that connect the rotating motor drive pulley to the desired turntable. You should observe that the wheels move correctly and engage fully when both FF and RW keys are depressed. If they are free to move, cleaning all driving surfaces with isopropyl alcohol, using a clean cloth or cotton bud may well help.

There is one common problem with these DC43 decks, after many years of use or storage.

The intermediate drive wheel, on the underside of the deck, that couples the motor pulley drive to the capstan flywheel, is mounted on a swivel arm, which allows it to move and sit snugly between the two surfaces it connects (and to move when the speed selector is altered).

The swivel arm is lubricated, but the grease dries out over the years, which can cause erratic operation of the drive to the capstan flywheel. It's a bit awkward to get to it and dismantle the swivel arm, in order to clean out the old grease and apply fresh. You have to remove the motor from its mounting plate, in order to gain access to the swivel arm and it's best to remove it.

I apply heat from a soldering iron to the affected part of the arm (which should swivel), in order to soften the grease and allow disassembly. Make a note of the anchor point of the spring that is attached to the swivel arm. I think the Thorn DC43 tape deck service manual (which you have) describes the removal process.

Regards,

Dazzlevision

Edward Huggins · 15th May 2017, 1:26 pm

Quote:

Originally Posted by ricard

If it's the Concertape I'm thinking of, it's the nasty stuff that was sold cheaply under all sorts of brand names in the 1970s, spooled on black reels with 6 holes, and MADE IN U.S.A. embossed along the rim.

That "Concertape" was sold off at the end in Radio Shack (when we had them here) at 99p and that's for an 1,800ft, 7" reel. I bought 10 thinking it was the bargain of a lifetime!

ben · 15th May 2017, 4:35 pm

Definitely due to the Sticky shed syndrome junk tape. That 'concertape ' was supposedly reject Ampex (which itself was Sticky -shed prone until the late 80s), as was 'Shamrock'. Avoid like the plague.

If you need to recover valuable content, then you can either bake the tape or some American forums report success by wiping it over with a car product called 'Nu finish'.

Chris55000 · 15th May 2017, 8:31 pm

Hi!

Thanks for your excellent advice, Member Dazzlevision - I can give it a go now I know what to lubricate & clean - should I get graphite lubricant from eBay or can you recommend a locally-sourced supply?

Can I use IPA on the rubber safely?

Ben & Edward, I hate to say but you've described exactly the tapes I got in that parcel of "clearout specials", and yes, there is a "Shamrock" amongst them!

So far I've found some BBC Radio London Country Top Ten, a number of episodes of "The Archers", and I fear there's some:-

"Now Then, Now Then, Now Then Boys And Gals!!!"

mentioned on the insides of the boxes as well!!!

Chris Williams

dazzlevision · 16th May 2017, 8:11 am

Quote:

Originally Posted by Chris55000

Hi!

Member Dazzlevision - I can give it a go now I know what to lubricate & clean - should I get graphite lubricant from eBay or can you recommend a locally-sourced supply?

Can I use IPA on the rubber safely?

Chris Williams

Graphite grease wasn't used originally - not the usual black colour. I use either sewing machine oil (just a small droplet) or very little lithium loaded grease. I bought both of these from Amazon UK.

I use IPA to clean "rubber" idler tyres and the like.

I have also had "solidified" grease cause problems with the engagement of the drive to the take up turntable on "play" and "record" functions. The large idler wheel that couples the capstan flywheel drive to the take up turntable doesn't engage properly. You have to release the tape heads mounting platform in order to access these components (no need to remove any wires though).

15th May 2017, 12:07 am	#1
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,864	Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind Hi! I tried my Marconiphone 4238 again after having been cajoied into household repairs at my friend's place where I'm now living, and when I tried a number of American 1800' "Concertape' brand tapes on them I found rewind very slow to the point of being almost having to turn the spool with my finger! Also, there's rather a lot of very rough-sounding squeaking whenever I try these tapes (they have a dark brown/black finish on the non-magnetic side and they are not paper-based, by the way), and another strange snag is that whenever the machine has been running half-an-hour or more, something starts to make a horrendous clattering noise that instantly stops if I turn the machine up or round! I have both the DC43 Deck and the Amplifier S.M.'s, other Members have commented on the build and running-quality of these decks, it's just like my luck to get one of the yukky specimens! Suggestions please? (I have to confess I'll gladly plough thro' a multi-valve, transistor or IC-based panel to the smallest minuitae to locate an obscure fault but mechanics and me don't agree with each other, even when I've got a full exploded diagram in front of me!) Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

15th May 2017, 5:47 am	#2
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind I would think these tapes would be susceptible to sticky shed syndrome, not to mention that it seems they are back coated, which is never suitable for a machine with pressure pads, which I believe the 4238 has. If nothing else, the pads clog up with dust from the back coating. If it's the Concertape I'm thinking of, it's the nasty stuff that was sold cheaply under all sorts of brand names in the 1970s, spooled on black reels with 6 holes, and MADE IN U.S.A. embossed along the rim. Found this video of someone demonstrating the sticky shed properties, as well as forcibly demonstrating what the person in question thought should be done with these tapes at the end of the video! https://www.youtube.com/watch?v=Hl11QHQTuD0

15th May 2017, 8:11 am	#3
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,608	Re: Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind Hello, The drive to the take up and supply turntables on the DC43 deck, is by moveable idler wheels that connect the rotating motor drive pulley to the desired turntable. You should observe that the wheels move correctly and engage fully when both FF and RW keys are depressed. If they are free to move, cleaning all driving surfaces with isopropyl alcohol, using a clean cloth or cotton bud may well help. There is one common problem with these DC43 decks, after many years of use or storage. The intermediate drive wheel, on the underside of the deck, that couples the motor pulley drive to the capstan flywheel, is mounted on a swivel arm, which allows it to move and sit snugly between the two surfaces it connects (and to move when the speed selector is altered). The swivel arm is lubricated, but the grease dries out over the years, which can cause erratic operation of the drive to the capstan flywheel. It's a bit awkward to get to it and dismantle the swivel arm, in order to clean out the old grease and apply fresh. You have to remove the motor from its mounting plate, in order to gain access to the swivel arm and it's best to remove it. I apply heat from a soldering iron to the affected part of the arm (which should swivel), in order to soften the grease and allow disassembly. Make a note of the anchor point of the spring that is attached to the swivel arm. I think the Thorn DC43 tape deck service manual (which you have) describes the removal process. Regards, Dazzlevision

15th May 2017, 4:35 pm	#5
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind Definitely due to the Sticky shed syndrome junk tape. That 'concertape ' was supposedly reject Ampex (which itself was Sticky -shed prone until the late 80s), as was 'Shamrock'. Avoid like the plague. If you need to recover valuable content, then you can either bake the tape or some American forums report success by wiping it over with a car product called 'Nu finish'. __________________ Regards, Ben.

15th May 2017, 8:31 pm	#6
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,864	Re: Thorn DC43 - Rattles after half-hour, Squeaks and slow/stopped rewind Hi! Thanks for your excellent advice, Member Dazzlevision - I can give it a go now I know what to lubricate & clean - should I get graphite lubricant from eBay or can you recommend a locally-sourced supply? Can I use IPA on the rubber safely? Ben & Edward, I hate to say but you've described exactly the tapes I got in that parcel of "clearout specials", and yes, there is a "Shamrock" amongst them! So far I've found some BBC Radio London Country Top Ten, a number of episodes of "The Archers", and I fear there's some:- "Now Then, Now Then, Now Then Boys And Gals!!!" mentioned on the insides of the boxes as well!!! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!