Akarakrit Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Wednesday, March 23, 2022

Studer D730 CD Player (Problem & Solution)

I've got this famous CD player from my friend with malfunction condition.

The problem is when power on the player, sometime it can run normally but will stop itself later

or cannot run since power on. Both situations indicate same word "Control Out" on display.

After search many information on internet, I've found this is common problem that many person had.

First they've recommended to replace Ni-MH battery that always leak after time has passed.

But after replacing battery, "Control Out" still appear on display.

Leaking Ni-MH battery cause hydrochloric acid so need to clean up nearby components.

No conclusion for real problem until I've found "Service Note 99-04" from Studer.


This service note mention about the defect of LM317T regulator IC and cause over-voltage to HEF4750

which is frequency synthesizer IC. So it can be damaged and effect the deviation of nominal speed.

I already read this note and follow the procedure to remove existing HEF4750 

then replace with 28 pins IC socket and use new HEF4750. I've found a good looking HEF4750

with ceramic body and gold pins on ebay, seem worth to try for me.

Compare existing HEF4750 and the new one with ceramic body & gold pins.

Using socket instead of directly solder to IC's pins.

But I thought capacitors in main power supply section on mainboard should be upgrade 

in same time too. So I select to using Nichicon KG (Gold Tune) amd KS (High Sound)

depends on original dimensions because of limit space to use all KG in this area.

Components that have been removed.

After replaced with higher quality capacitors.

I also found this great forum here


that use smart idea to fix LM317T heat problem with move this IC to main heatsink

using connecter and wiring. So I've made with new LM317T like this 

and I thought this is the good way to follow.

Existing LM317T located in limit space between large capacitors and connecter.

After remove LM317T to main heatsink with connecter & wiring.

Add heatsinks to LM317T & LM337T near TDA1547 too.

After replace all components that I've mention, then I turn on power switch.

Everything work normally a long the week without any issue.

Seem this "Service Note 99-04" is the good guide if anyone had this same problem.

The sound of Studer D730 with TDA1547 "DAC7" is natural, not warm like TDA1541

but compromise with many kind of music. Will try external clock and external DAC later.


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