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Old 14th January 2006, 04:23 PM   #1
g'wyn is offline g'wyn  United States
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Talking Theta Transport Drive Wheel

The drawer on my Theta Pro Basic CD Transport stopped dead the other week. I opened the case to find only a few teeth left on the drive wheel.
The teeth had been stripped off because the soft plastic gears had broken down from steady use & the case's interior heat.
Called Theta Techincal: No parts left, I was told, without further help, leaving me with a $1,500 lump.
Nothing motivates me faster than to be told that something can't be fixed.
Off to the internet I went. Searching for "theta" led m to dyiaudio.com, then a message from Thomas in HongKong. Was I lucky!
Thomas has some replacement wheels he had made with tougher plastic, and would send me two by airmail to US for $25. I sent him the money thru Paypal and guess what?
The wheels arrived yesterday! Thanks Thomas. Thanks dyiaudio.com.
My Theta lumb will be back in business as soon as I can mount the new wheel on the drive spindle.
Anyone have any tips on how to mount it?
--g'wyn
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Old 14th January 2006, 06:05 PM   #2
g'wyn is offline g'wyn  United States
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Default Spelling

That's Theta Technical & Theta lump not lumb.
Sorry
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Old 14th January 2006, 10:50 PM   #3
tubenut is offline tubenut  South Africa
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Putting the new gear wheel in is dead easy!!!!

But take a little care....

Try and work static safe with a wrist strap if you can.. Failing that work barefoot on a tile floor perhaps on your (metal) kitchen sink.
IOW, be careful of electrostatic discharge. If you do not have the ES safe gear be careful, no woolen jerseys and rubber soled shoes etc.



You will need a torx screw driver, not sure of size but it is the common size if that helps. You may be able to cheat with a flat that fits into the teeth of the torx.

Take the lid of the Transport (Duhhhh)

Unplug the multi colour ribbon cable from the loader PCB.
At the bottom of the Theta are 3 screws that hold the loader in place, remove them making sure you do not drop the loader.

Remove the loader, disconnect the plug that connects the brown and black wire on the right hand side (I think, could be left) next to the loader draw.
Now turn the loader upside down and remove the other similar connector that connects to the PCB horizontally make a note of this connection as there are two sockets (one is blank) and on re assembly you need to usee the right one (no dammage, controls will just behave stupid if you get it wrong...)
I would recommend to now manually pull the drawer out (loading a cd position) as this will give slightly more length to the flex foil connectors from the laser and motor to the PCB that will be usefull when you need to flip[ the pcb up just now.
With the loader upside down, observe the way the belt runs etc.
With the face of the drawer away from you and motor towards you remove the 3 screws that hold the PCB in place.

Now comes the toughest part.
Lift the PCB upwards (about 60 degrees) on the motor pulley side, not at the front as it is connected with delicate flex foils on that end.

Lift out the plate that holds the spindle and gear that you wish to replace.

Drop the PCB gently.

The gear is press fitted onto the shaft, just pull it off.

Clean the shaft, regrease shaft and pop the new gear on shaft untill it clicks in to place.

Lift the PCB again and hook the belt around your new gear and refit etc in reverse as per the steps above.

Before fitting the loader back into the chassis I would clean all the grease you can of the drawer teeth. It is said that the grease used reacted with the plasticv of the gears making them brittle. Re applly a non agressive grease. Perhaps silicon grease/oil.

Be carefull of the flex foils, do not attempt the cleaning of the draw teeth with the PCB loose as there are good chances you rip a flex foil, if you rip the flex foil from the motor your Theta wil RIP!!!!

After cleaning and greasing, connect and tighten up everything and your CDP is good to go!!!!












.
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Old 15th January 2006, 04:21 PM   #4
g'wyn is offline g'wyn  United States
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Default Theta Wheel

Hoot, man, thanks ..
Already opened Theta case, so know most of your precautions. For grease in audio equipment, I use:
a) Silicon spray on a cotton tip applied gently or
b) Silicon lubricant for spinning fishing reals. This stuff is great!
Your tips on spindle & how to replace wheel is what I needed, which I'll try later today after our big football playoff matches.
--gwyn
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Old 15th January 2006, 04:21 PM   #5
g'wyn is offline g'wyn  United States
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Default Sink

Tubenut:
Forgot one thing: I know have to go out & buy a metal sink!
g'wyn
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Old 17th January 2006, 11:07 PM   #6
g'wyn is offline g'wyn  United States
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Default Installed Theta Wheel, YES!

Tubenut:
Got up the courage today to install a replacement Theta drive wheel I got from Thomas in HongKong thru diyaudio.com.
With a magnifier lamp, working almost almost like a jeweler, I used an X-acto hobby knife with new sharp blade to clear the plastic debris from the broken gears from the top of the spindle shaft, gently, gently. then eased the damaged wheel off.
Cleaned spindle shaft with silicon lubricant, attached Thomas’s replacement wheel and it snapped on with a click!
I am so grateful to Thomas in HK -– especially after Theta said nothing could be done. Indeed!
Cheers Gang!
--g'wyn
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Old 18th January 2006, 06:22 AM   #7
tubenut is offline tubenut  South Africa
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Glad you got it sorted, it is a nice drive...
Now that you got into DIY CDP work there are a lot of oother worthwhile things you can do to hot rod this transport.
My posts somewhere give details.

Big improvement that is simple is upgrading the intternal digital interconnect. I would recommend you use something similar to what you use outside..
If you are using AES/EBU (the XLR) digital, that output internally is set up for 75 ohm not 110. It takes swapping 2 resistors to sort this out and again big improvement...

I think it sad that theta say the gear is no more. I got some via philips about 6 months ago, no problem.

Glad we could help. This forum is absolutely great and has helped me a great deal. I am grateful for it every day I listen to my Theta. (Bought as scrap for about USD 80 as local agent said it could not be fixed)
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Old 19th January 2006, 02:25 PM   #8
g'wyn is offline g'wyn  United States
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tubenut:
searched diyaudio digital forum for your earlier mods for theta transport or dac, but could only find one -- the output resistor change.
how can I find the others?
cheers!
--g'win
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Old 19th January 2006, 08:19 PM   #9
tubenut is offline tubenut  South Africa
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Hi Gwyn

I noticed my comments are quite scattered across many posts……

Here is the bulk of it in no particular order…….

The easiest is to dampen the case internally with adhesive automotive bitumen damping sheets. Car audio places are sure to keep it.

As I said before Digital cables used from the main PCB to the output connectors. This looks real low rent stuff and I rewired using Apogee Wyde Eye AES and Co Ax cables.

I changed the SPDIF RCA to a BNC, very worthwhile to run BNC instead of RCA but it means doing top your cables also..… If you use co ax

The AES output is set up for 75 Ohms…. rectified by changing resistor 17 and 18 to 55 Ohms. (Actually 56, could not get 55)

The power supply diodes were changed.
I used BYT53 all round, one of my faves as it is fast, soft recovery and not bulky. You will need 16 diodes to replace 3 bridges and 4 separate diodes. There are diodes/bridges on the main PSU pcb, the main PCB as well as on the extra powersupply PCB that was the retrofit update from MK1 to 2. If you have a factory mk2 there will be 4 transformers and bridges on the PSU pcb, not 3.

If you have a MK1 unit that has not been updated to MK2 you can DIY this by building a separate DC supply running of its own transformer, you remove a resistor feeding the regulator to the clock cct and feed your dc supply via an inductor to this regulator. The clock now has its own dedicated separate powersupply.


I also changed 2 of the 47 mfd electrolytic caps near the IF demodulator for some os-cons.

Used some chunkier cable to wire up the power switch as my high quality mains lead was sure to be choked by the bell wire used to wire the switch to the PCB

I lead taped the crystal and then covered it in amalgamating tape as well as earthed the can and feed it to the PCB via thin wires while the crystal lies in a lump of blue tack, that made a nice difference.

Theta uses something more then the standard Pierce clock circuit already.... Replacing the 4 clock caps 2 x 68nf and 2 x 22nf with silver mica types was very worthwhile.
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Old 18th March 2008, 01:10 AM   #10
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Default Data Basic

Oh my god exact thing just happened to me but I have the Data Basic is it the same? Gear fell apart. Theta does have them but wants $100. Can you give me the name of the guy you got the gear from?
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