My new effort on making the ultimate DP-80 - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th February 2014, 11:24 PM   #11
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Very impressive machining. Have you ever thought of taking the motor out of the chassis and install onto your machined plinth? Even with all these heavy duty fabrications, the motor is still bolted to the flimsy aluminum chassis. Of course, if you take the motor out you have to deal with the servo system and remount/reposition precisely the tapehead assembly and extend all the cables separately, sort of like the Kaneta mod with the Technics SP10Mk2 system. I believe the Denon's induction motor is two wires and the tapehead is another couple wires. I think Mitch Cotter did something similar except his is a suspended plinth. Anyway, keep us updated and have fun!

.

Last edited by directdriver; 8th February 2014 at 11:27 PM.
  Reply With Quote
Old 9th February 2014, 05:02 PM   #12
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
I understand your point directdriver.
The motor is a three phase out unit and has three wires.
The tapehead used is "stereo"... so four wires.
The positioning and measuring is not so difficult and i have thought of that but the cost of reproducing the complex top area would add at least another 1000 euros to the bill.
The cast top is not so flimsy... it has an around 5mm thickness and it's generously ribbed.
I have puzzled myself about this issue and i have found ways to reinforce/damp it ... to be described soon.
By the way it is all conceived, the exoskeleton will add it's mass and damping on the internal parts.
I am familiar with the Cotter mods and the Kaneta SP-10 mods.
I think that this goes multitudes beyond.
Thanks for watching...please keep commenting...and yes i've had tons of fun!
__________________
soundofvoid
  Reply With Quote
Old 10th February 2014, 07:12 AM   #13
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Quote:
Originally Posted by soundofvoid View Post
but the cost of reproducing the complex top area would add at least another 1000 euros to the bill.
I don't think the "top area", assuming you mean the stock chassis that houses the motor, needs to be recreated. I would keep the stock chassis simply as the housing for all the electronics, sort of an outboard power supply, and extend the cables to the main plinth which can be created to your heats content. Unless you are so enamored with the stock flying saucer look that you want to recreate everything including openings for the buttons, switches, and LED, etc... If original aesthetics is a concern then please disregard my suggestion as I understand we all have our desired visuals. I always wanted to do something like that myself but I don't have the tools, skills, and resources to embark on such project. My inspiration is something like the Monaco Grand Prix direct drive turntable or the Micro Seiki DDX-1000, believing electronics should be separated from the motor in DD system. Anyway, you get the idea and I look forward to your future updates.

Once again, happy listening!
  Reply With Quote
Old 10th February 2014, 08:40 AM   #14
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
I really like both turntables that you mention.
Micro was so much ahead of it's time...
You got me there: I really like the "flying saucer" look and it would be a nightmare to recreate with a CNC all the complex openings and hook up points for all the mechanisms.
So i chose to keep from the original the top part.
All the control boards / PS boards and transformers will be positioned in a dedicated
power supply/control box and will be connected with an umbilical cord to the turntable.
On the stock chassis all is left is the motor the tape head and the buttons.
Below are some photos of the process of stripping everything out.
I had to get my hands on the bare chassis and main components to
see what could be done to improve on them...
Attached Images
File Type: jpg Photo0319-Optimized-1.jpg (132.2 KB, 282 views)
File Type: jpg Photo0232-Optimized-1.jpg (109.4 KB, 276 views)
File Type: jpg Photo0234-Optimized.jpg (105.4 KB, 260 views)
File Type: jpg Photo0238-Optimized.jpg (108.1 KB, 258 views)
__________________
soundofvoid
  Reply With Quote
Old 10th February 2014, 09:42 AM   #15
Dyolf is offline Dyolf  Norway
diyAudio Member
 
Join Date: Apr 2009
Quote:
Originally Posted by directdriver View Post
Even with all these heavy duty fabrications, the motor is still bolted to the flimsy aluminum chassis.

.
I'm actually in agreement with Soundofvoid regarding the chassis. It dos'nt look flimsy at all. What I do know is that the similar Technics types players, the SP-range, has a rumour of a "ringing" chassis, that many have tried to fix by dampening it in different ways. Also I kind of like the idea of removing as much as possible of the electronics, and place it in an outboard box.
Steen
  Reply With Quote
Old 10th February 2014, 10:15 AM   #16
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
At some point you come to understand that it's not the actual thickness of the metal
(up to a point of course) that damps ringing.
The aluminium bottom plate of the chassis is 40 cm in diameter , 3 cm thick, several kilos in weight and still rings like a bell when you tap it.
The same (to a much lesser degree) goes for the 1.5cm thick leaded iron plates
between the aluminium ones.
However, when these two different metals are screwed tight together the ringing disappears.
They counteract each others characteristics and produce a very well damped mass.
The top part is cast aluminium, the ribs add strength and break ringing and there is
a 2mm black steel cover on top (under the platter) that i used (among other things) to add damping to the chassis by placing a sheet of sorbothane compressed under it.
__________________
soundofvoid
  Reply With Quote
Old 11th February 2014, 05:27 PM   #17
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
It was time for a check on the heart of the system:the motor/spindle section.
The supporting U part comes of by taking out four screws.
You can see the condition of oil and the debris on the thrust plate after 30 years.
The thrust plate is steel and so is the tiny ball (3mm).
The flange was like new and so looked the axle.
To take the rotor part in hand a circle clip has to be removed.
I decided to renew the self lubricating bronze bushings with longer versions since i was aiming for a much heavier platter.
I also decided to use a completely new thrust plate/ball scheme in search for even lower noise.
I would use a 3 mm thick teflon thrust plate and a 6.7mm ceramic ball.
I didn't like the solidity of the aluminium U part and i started thinking about ways to improve on it.
Attached Images
File Type: jpg Photo0240-Optimized.jpg (119.9 KB, 254 views)
File Type: jpg Photo0236-Optimized.jpg (122.8 KB, 136 views)
File Type: jpg Photo0347-Optimized.jpg (120.7 KB, 148 views)
File Type: jpg Photo0350-Optimized.jpg (80.9 KB, 131 views)
File Type: jpg Photo0343-Optimized.jpg (71.9 KB, 111 views)
__________________
soundofvoid

Last edited by soundofvoid; 11th February 2014 at 05:38 PM.
  Reply With Quote
Old 11th February 2014, 07:43 PM   #18
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Quote:
Originally Posted by soundofvoid View Post
I didn't like the solidity of the aluminium U part and i started thinking about ways to improve on it.
I like the way you think.

It would be nice if it's circular and covers the whole circumference or at least using three point support.

I wish I am a machinist!


PS, Correction: earlier I called the Denon motor as "induction motor" and after looking at more pictures. It is not and looks like a typical AC core motor with magnet and using tapehead servo. I am familiar with some of Denon's earlier models which I opened before and they are induction motors.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Here's a wonder Japanse website that show repairs of everything, including Denon turntables.

A repair from 2002.

A repair from 2008.

Check them out.

.

Click the image to open in full size.

Last edited by directdriver; 11th February 2014 at 08:03 PM.
  Reply With Quote
Old 12th February 2014, 10:16 AM   #19
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
I know this japanese site of the repair shop from the vintageknob.org!
It seems that we all have the same habits...and like the same things.
I wish i was a machinist and an electrical engineer too!
It's good that i have friends that have these skills and help me with my crazy ideas!

Now, regarding the platter that is a two part design:
The lower disc fits securely (conical shaped hole) on the axle and the top part is suspended with three leaf springs and damped at the periphery with a sponge like material...which after all those years has deteriorated and is completely useless.
I did like the sandwich approach on the platter but i had problems to solve.
I was going to use an extra metal mat and a periphery ring to add weight
and inertia and that would alter the parameters of the suspension/damping.
I have decided to keep the leaf springs and use as a damping agent, a soft (grade 40) sorbothane layer that would always be in contact with both parts of the platter.
My tests proved very rewarding and i decided to do it this way.
Attached Images
File Type: jpg Photo0241-Optimized.jpg (94.2 KB, 90 views)
File Type: jpg Photo0243-Optimized.jpg (108.1 KB, 95 views)
File Type: jpg 20131023_195043-Optimized.jpg (93.5 KB, 110 views)
__________________
soundofvoid
  Reply With Quote
Old 13th February 2014, 11:35 AM   #20
diyAudio Member
 
Join Date: Apr 2007
Location: Glyfada/Athens
First thing i did was fill up the peripheral cavity of the top chassis with liquid bitumine.
You can buy it in cartridges (just like silicone).
It starts up as semi liquid substance mixed with fibers of some kind and cures gradually to a state that mimics sorbothane.
It's a bit messy but stops any ringing...a solid "thud" is heard when you tap it.
Then it was time for taking out all the old and suspect parts from the boards.
New equivalents were used with a bit uprated capacities (all long life 105 deg)
in the PS section and regulation and more powerful transistors to cope with the heavier loads.
An order was made for the PSU box so that i could place the boards in, the same way that they were in the original chassis.
Attached Images
File Type: jpg Photo0265-Optimized.jpg (114.0 KB, 112 views)
File Type: jpg Photo0266-Optimized.jpg (147.9 KB, 79 views)
File Type: jpg Photo0245-Optimized.jpg (106.6 KB, 76 views)
File Type: jpg Photo0342-Optimized.jpg (122.1 KB, 70 views)
File Type: jpg DP-80 complete renewal.jpg (39.5 KB, 100 views)
__________________
soundofvoid
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Accuphase DP-80 CD Not Reading flyong Digital Source 17 27th November 2014 05:11 AM
Monsterizing a Denon DP-80 soundofvoid Analogue Source 46 26th August 2012 02:38 AM
Yamaha C-80, T-80, M80's FS or Trade JEakins Swap Meet 1 6th June 2010 10:40 PM
Marantz SC-80 / SM-80 repair queries Low Orbit Solid State 2 26th May 2010 07:36 PM
A *what* effort!?. Circlotron Multi-Way 5 19th September 2004 01:37 PM


New To Site? Need Help?

All times are GMT. The time now is 09:07 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2