Thorns TD160B restore

Love it or hate it, it just won't stop
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#121

Post by Mike H »

Greg wrote:You guys looking into Rega upgrades would do well to study here.
Ah yes seen that, way OTT tho for my humble purposes

colin.hepburn wrote:
colin.hepburn wrote:Hi All
<anip>
So why are you messing with the earth wire
Are you asking me?

The simple answer is I don't need a full blown rewire, but the earthing could be better arranged
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
colin.hepburn
Shed dweller
Posts: 2294
Joined: Sat Jun 02, 2007 1:24 am
Location: Scotland Aberdeenshire

#122

Post by colin.hepburn »

AH ok i did wonder :)
so rega not too hot with there wiring then :shock:
Colin
The Blues man ImageImage
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#123

Post by Mike H »

Hi Colin, not too bad really to be fair, the arm wiring is not exactly Litz but very fine, it's just that thing about how the arm tube is actually earthed. I expect it is quite common in lots of makes to make it onto one of the signal screens, guess they need to make sure it's actually connected to 0V so as to ensure the arm wires are screened properly, since there's no way of knowing whether it'd be earthed right otherwise by whoever installs it! I.e. have to cover all eventualities. The Thorens standard arm is the same.

Understand what you're saying, 'cept that in this particular case making sure the treble's OK isn't going to be a problem, in fact as it is I'm still going to have to add extra caps to the phono inputs to knock it down!

Fear not there is method in my madness Image

Anyway seem to have come to the end of that particular preparation, suppose the next step is tearing down the old set-up. When I've got a spare half hour or two :D
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Greg
Social outcast
Posts: 3201
Joined: Wed May 23, 2007 11:14 am
Location: Bristol, UK

#124

Post by Greg »

Hi Mike,

Picking up your your earthing concern, I agree the standard fitting of an interference fit sprung piece of thin plate just inside the armtube at the bearing end does not seem ideal. I know because I've dismantled an RB250 today. All the Rega upgrade derivative companies deal with this one way or another. I'm not sure what the Michell solution is but Origin Live fit a spigot into the end of the armtube at the headshell end and solder earth to that. The Audio-Mods link I gave you above has an alternative option worth considering. I hope that helps.

Best wishes,

Greg
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#125

Post by Mike H »

Yes very true, tho there's two issues at work here ~ the arm is positively earthed thru the black wire, however does not make electrical contact to its base thru its bearings. Or not very well. Hence, shove a bit of bendy metal down the side of the insert bit so the connection contacts the base as well. :D

I'm not too fussed about the base TBH, provided the actual arm is properly shielded. Which it is. Image
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#126

Post by Mike H »

Finally did something today, went a bit 'mad' this arternoon and this evening and practically got everyfink done bar proper setting up


First, unsolder arm wires and rip out terminal thingy ~ spade connectors, I mean :roll:

Image


Release cue control cable connection from orft arm base...

Image


Remove three screws, arm falls out...

Image


Remove springs...

Image

.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#127

Post by Mike H »

... and sub-plate is loose.

Image


Remove 'remote control' cueing thingy and lose it. (Perhaps not really.)

Image


Make arm 'ole more biggerer...

Image


... so new arm fits summink like this innit...

Image


.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#128

Post by Mike H »

Sub-plate back in, mit Dynamat stuck on where possible...

Image

.. including the plinth sides.


Image


Ta-da!

Image


Image


Bit of twiddling the spring nuts to level it, proper job. Image


NB bit of a cock-up re armboard screws positioning, but sorted it okay. Turns out needs two spacer washers on top. Bit of thick card stuck on underneath to match thickness of sub-plate so Michell nut is flush all around. Well practically.

.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Greg
Social outcast
Posts: 3201
Joined: Wed May 23, 2007 11:14 am
Location: Bristol, UK

#129

Post by Greg »

Hi Mike,

Nice job. With all that Dynamat stuff you have introduced considerable weight to the the sub-chassis the suspension now needs to deal with. Historical upgrading experience is that this can be dealt with by replacing the Thoren's springs with Linn LP12 items (direct slot in exchange items) and these can be readily had second hand for a nice price (even free) from any accommodating Linn dealer. This is what I did in a similar situation and certainly found balancing the TT much easier and I also think the sound improved albeit I'm seeking into very old memory. Potentially this is a free upgrade option so go out there and find some LP12 springs. You won't regret it.

I hope you've also done something with the bearing. Originally designed to run dry on the ball bearing, it benefits from a bit of Mobile 1 oil albeit there is no space in the bearing for reservior.

Best wishes,

Greg
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#130

Post by Mike H »

Thanks Greg,

Way ahead of you, what looks like a bit of rag stuffed into bearing hole is actually screwed up newspaper cos it already got engine oil in it. Didn't want it dribbling out all over the place. :D

Re springs, I just twiddled the nuts so it's just hanging free and equal all around with the all up weight on. Seems alright Image

Nut heights hardly different to originally, so far as I can tell.

Got it back on the shelf last night and levelled it with spirit level. As far as I've got so far.

PS forgot to mention the yellow spongy foam damper thingies (whatever they're supposed to do) that are originally inside the springs are omitted as well.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#131

Post by Mike H »

Well it works anyway! Image

As I write it's currently playing Dusty Springfield.

I might be mistaken but I may not have been fully aware before that 'Little By Little' is actually in stereo Image ~ not by very much admittedly

Had to jiggle the arm position a bit more to get the actual 222mm between centres. Then I used a Stevenson protactor which I drew (well, modified an existing one) which includes the 15mm overhang marking.

Having got the stylus on the ovehang mark (isn't it useful that the arm rotates enough to go over the centre spindle!), squared it on the inner grid, then lo and behold when moved to the outer grid it lines up. Just like that.

When finished moving the cartridge about, VTF next, used a cheap-n-cheerful balance, but does the job (was calibrated on the TP16 arm). The Nagaoka requires 2 grams, or a shade under. Nip up the counterbalance Allen grub screw, sorted.

Crikey the antiskate is a bit powerful innit? Image Shifted it up to 2g (far as it will go), and it's dragging the arm on the rest! '1' seems quite enough. Can't see the cantilever bending one way or the other, and 0.5 (antiskate) not enough (top treble goes off a bit on left channel).

Lastly 330pF mica caps added to phono pre input sockets so's it's running into >500pF.

And that's how you do that...
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#132

Post by Mike H »

Progressed from Rusty Springboard to Atlantic Soul Classics, now onto The Fifth Dimension...

8)
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#133

Post by Mike H »

I'm a stupid berk! Forgot about the Miller effect! Image

Phono pre uses two 6SL7 in parallel for the input stage.

Cga of 6SL7 = 3pF (worst case, 3.5pF)

Two 6SL7's in parallel = 6pF (worst: 7pF)

6pF x gain of X50 = 300pF

Worst case:
Cga = 3.5pF, x 2 x gain X50 = 350pF

Plus internal cables, fairly sure about 100pF each, = 450pF

Plus connecting leads, 120pF, = 570pF!

No it don't need any extra help then!

Right so, out you go ... [n33F micas]
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
colin.hepburn
Shed dweller
Posts: 2294
Joined: Sat Jun 02, 2007 1:24 am
Location: Scotland Aberdeenshire

#134

Post by colin.hepburn »

Ho Well try again Just got my copy of the HIFI news Test record arrived on Friday yep would you beleve it warped bloody Royal mail still the dealer was ok about it and sending an other copy in a bigger box this time :)
Colin
The Blues man ImageImage
User avatar
Mike H
Amstrad Tower of Power
Posts: 20189
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#135

Post by Mike H »

Remind me, what's that got on it?

Yeah Royal Mail you still must put "Fragile" or "do not bend" on things.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
Post Reply