Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
I'm having power issues with my BII that has been up and running a year now. Setup is BII with Tridents powered by Placid HD (Placid previously). Go through the Placid HD setup, set to 5.25v, adjust current to 530 mA, everything is good. Power down, connect the BII, power up, and the voltage drops to 4.35v. Adjusting the voltage via VR2 has no effect. Increasing current also has not effect. Interestingly, music plays ok.
It had been running fine with regular Placid when I noticed this voltage sag. I thought maybe the Placid had failed so I ordered the Placid HD. Same result.
Any ideas?
|
|
|
|
|
|
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)
|
Does increasing the current output of the Placid have any effect?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
Sound like a short from a damaged component. Maybe a trident? Try measuring the current into each Trident.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
What is the most straightforward way to do that?
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
remove the connection to VD on the trident under test and use a DMM to measure current by putting one probe on VD (or another 5V source source) and one to the input of the trident. The easiest way to do this is to remove the Tridents and test them each outside the DAC. Edited by user Sunday, September 18, 2011 1:22:42 PM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
Found time this pm to make the measurements. They are:
VDD: 304 mA
VDD_XO : 53 mA
DVCC: 53 mA
Also noticed that VDD gets quite hot. Looks like it's the problem. Is it repairable or should I replace it?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
Is it worth trying to swap out the opamp? Looks like a National Semi LMP7731MA.
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
Yes your VDD module is dead.
If the LEDs are still lighting correctly then it is worth trying to replace the op amp and/or the transistors if you are up to it.
If you are wanting the easy solution then I would just order another one, but it depends on your rework skills.
Cheers!
Russ
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/1/2010(UTC)
Posts: 19
Location: Snowy WIsconsin
|
Thanks Russ. What transistor parts should I order? Looks like QP1 and QP2.
|
|
|
|
|
|
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.
