Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error

Login
Low Output Voltage
Options
View
Go to last post Go to first unread
Previous Topic Next Topic
sachsm  
#1 Posted : Monday, April 2, 2012 2:05:36 PM(UTC)
sachsm

Rank: Member

Groups: Member
Joined: 3/9/2012(UTC)
Posts: 12
I am only seeing a .9V voltage swing on the toslink output. It is enough for the Opus receiver but
I would also like to try driving a standard TTL input. The spec on the TORX module indicates that I should
have at least a 2V output. I have order a new optical interconnect cable but wanted to first see what to expect.
Back to top

Wanna join the discussion?! Login to your Twisted Pear Audio Support forum accountor Register a new forum account.
Back to top  
Brian Donegan  
#2 Posted : Monday, April 2, 2012 2:11:30 PM(UTC)
Brian Donegan

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 2,868
Location: Massachusetts, USA

Thanks: 2 times
Was thanked: 141 time(s) in 134 post(s)
The module should be outputting TTL-level (3.3V). What are you measuring with?
Back to top
WWW
sachsm  
#3 Posted : Monday, April 2, 2012 2:42:42 PM(UTC)
sachsm

Rank: Member

Groups: Member
Joined: 3/9/2012(UTC)
Posts: 12
Agilent DSO, 200 MHz. x10 probe. The I2S signals on the Opus board are 3.3V but the TORX output is ~.9V
In all other respects, the TOSLINK signal looks good, clean waveform, just low amplitude. I have tried 2 different
TOSLINK modules and they are both the same. Could it be the fiber cable?
Back to top
sachsm  
#4 Posted : Monday, April 2, 2012 3:04:37 PM(UTC)
sachsm

Rank: Member

Groups: Member
Joined: 3/9/2012(UTC)
Posts: 12
It appears that the 75 ohm resistor to ground (R1) on the Opus module is attenuating the TOSLINK signal.
What is the recommended hookup between the OPUS and the TOSLINK module?
Back to top
sachsm  
#5 Posted : Tuesday, April 3, 2012 8:26:50 AM(UTC)
sachsm

Rank: Member

Groups: Member
Joined: 3/9/2012(UTC)
Posts: 12
Ok, looking at the Wolfson WM8804EV1 evaluation board schematic, it seems that the recommended connection to the Toslink output is direct wiring to the
RX input on the 8804. I plan on removing the 75 ohm to ground and shorting out the .1uf series cap to accomplish this.
(It seems like it would be a simple matter to add a jumper to allow selection of TOSLINK or Coax on the Opus module)

Edited by user Tuesday, April 3, 2012 8:29:27 AM(UTC)  | Reason: Not specified
Back to top
Brian Donegan  
#6 Posted : Tuesday, April 3, 2012 8:29:50 AM(UTC)
Brian Donegan

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 2,868
Location: Massachusetts, USA

Thanks: 2 times
Was thanked: 141 time(s) in 134 post(s)
That will work.
Back to top
WWW
Rss Feed  Atom Feed
Users browsing this topic
GuestUser (2)
Similar Topics
Buffalo III low output voltage -- BIII toast? (Buffalo DAC)
by Stunts 4/12/2014 9:50:04 AM(UTC)
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Youtube
Copyright © Twisted Pear Audio