Dead Studer A730

lumanauw · 22nd October 2007, 02:53 AM

I've got a friend who has a dead Studer A730. I'm not familiar with digital, but is it possible to fix this CD player? What to check first?

MadMutt · 22nd October 2007, 04:03 AM

Define dead.

Had a 225 (?) revox here that wouldn't power up.
Was some shorted electrolytic caps on the power board.
Had blown the fuse because of this.

lumanauw · 22nd October 2007, 04:56 AM

Nothing happens when the ON knob is pushed. All the displays are dead, nothing happens when any of the buttons are pushed on.

jives11 · 22nd October 2007, 05:13 AM

at the risk of suggesting the obvious, is there an internal fuse ? I have an old Philips 104 and the Power supply has a fuse on the circuit board , accessible only from underneath, having removed the lower plate.

MadMutt · 22nd October 2007, 06:03 AM

I can garantee theres a fuse (or more) inside the unit.
Pics I've seen of the 731 version would suggest that they also have a fuse IN the power socket on the rear panel.

That'd be my first check.

georgehifi · 22nd October 2007, 07:22 AM

Quote:

Originally posted by lumanauw
I've got a friend who has a dead Studer A730. I'm not familiar with digital, but is it possible to fix this CD player? What to check first?

If you can use it lumanauw,
ftp://ftp.studer.ch/Public/Products/CD/A730/Manuals/

Cheers George

lumanauw · 22nd October 2007, 09:44 AM

Hi, Everybody,

Thanks for the inputs

Thanks, Georgehifi. That is one big file, 59Mb

From quick check, all the fuses are OK (2 fuses are inside the AC plug-in, 4 fuses inside the unit).
I found something strange. The voltages at opamp rails are not symmetrical, +11Vdc (pin8) and -14Vdc (pin4).

lumanauw · 24th October 2007, 09:17 AM

Hi, Everybody,

I've looked more closely through the dead StuderA730.
-From outside panel (keyboard) not 1 single LED is on. All LEDs and 7segments are off, no matter what button I push, nothing happens.
-If I put a CD inside the tray, the CD spins, but no LED or 7segments is on. All indicators are dead.
-All the fuses are OK, the DC voltages from power supply are all present and normal. 2 LEDs are illuminating inside the unit, one red LED and 1 green LED on the right-down corner.
-The power supply heatsink (a piece of aluminum sheet) is a bit hot.
-There's an IC with code SAA7220 (position near TP5-TP6) is very hot. Is this normal? From the datasheet it is a digital filter IC.

Here's voltage measurement on Test Points (TP) as I measured them VS as written in the service manual.
I measure the voltage in dead condition, the service manual said the voltages are in "play mode", so could be different.

Anyone can help to interprete what is going on?

stephensank · 24th October 2007, 03:57 PM

You probably have one or more power supply filter caps going bad. If you measure more than 10mV or so of AC voltage on the regulated DC supply lines(like the points where you got 11 + 14v), then look for the big lytic caps before the supply regulators to be bad.

MadMutt · 24th October 2007, 09:30 PM

I'd also go the re-cap route.
It's what stopped the one (226 vintage) I had here.

Although the display issue may not be affected by this.

22nd October 2007, 02:53 AM	#1
lumanauw diyAudio Moderator Emeritus Join Date: Oct 2002 Location: Bandung	Dead Studer A730 I've got a friend who has a dead Studer A730. I'm not familiar with digital, but is it possible to fix this CD player? What to check first?

22nd October 2007, 05:13 AM	#4
jives11 diyAudio Member Join Date: Mar 2004 Location: Hampshire	check for fuses at the risk of suggesting the obvious, is there an internal fuse ? I have an old Philips 104 and the Power supply has a fuse on the circuit board , accessible only from underneath, having removed the lower plate.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Studer B67	exurbia	Swap Meet	3	14th May 2012 12:45 AM
Studer A721	Ghianni	Analogue Source	12	6th April 2011 12:42 AM
Studer A730 advice	glasgowhifi	Digital Source	3	5th May 2009 02:12 PM
Studer 52	Franz Gysi	Tubes / Valves	3	11th March 2008 07:40 PM
Studer 727 slave to DAC ?	Bernhard	Digital Source	0	28th July 2006 07:48 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

22nd October 2007, 04:03 AM	#2
MadMutt diyAudio Member Join Date: Nov 2006	Define dead. Had a 225 (?) revox here that wouldn't power up. Was some shorted electrolytic caps on the power board. Had blown the fuse because of this.

22nd October 2007, 04:56 AM	#3
lumanauw diyAudio Moderator Emeritus Join Date: Oct 2002 Location: Bandung	Nothing happens when the ON knob is pushed. All the displays are dead, nothing happens when any of the buttons are pushed on.

22nd October 2007, 06:03 AM	#5
MadMutt diyAudio Member Join Date: Nov 2006	I can garantee theres a fuse (or more) inside the unit. Pics I've seen of the 731 version would suggest that they also have a fuse IN the power socket on the rear panel. That'd be my first check.

22nd October 2007, 09:44 AM	#7
lumanauw diyAudio Moderator Emeritus Join Date: Oct 2002 Location: Bandung	Hi, Everybody, Thanks for the inputs Thanks, Georgehifi. That is one big file, 59Mb From quick check, all the fuses are OK (2 fuses are inside the AC plug-in, 4 fuses inside the unit). I found something strange. The voltages at opamp rails are not symmetrical, +11Vdc (pin8) and -14Vdc (pin4).

24th October 2007, 03:57 PM	#9
stephensank diyAudio Member Join Date: Oct 2006	You probably have one or more power supply filter caps going bad. If you measure more than 10mV or so of AC voltage on the regulated DC supply lines(like the points where you got 11 + 14v), then look for the big lytic caps before the supply regulators to be bad.

24th October 2007, 09:30 PM	#10
MadMutt diyAudio Member Join Date: Nov 2006	I'd also go the re-cap route. It's what stopped the one (226 vintage) I had here. Although the display issue may not be affected by this.