Bypassing circuit's own rectifier

Reply

  #1  
Old 12-16-15, 06:36 PM
V
Member
Thread Starter
Join Date: Dec 2015
Location: The Netherlands
Posts: 4
Received 0 Votes on 0 Posts
Bypassing circuit's own rectifier

Hello there!

I've built my own (not yet) portable stereo, and it got a mixer in it. All the devices run on a DC input but the mixer takes an AC input. Now I want to dissolder its rectifier and wire it directly to a DC power supply/battery.

But I have a hard time figuring out which part of the circuit is the rectifier.
I've included pictures I've taken of the circuit.

Does anyone have an idea of how I should go on about this?

Name:  20151217_022919.jpg
Views: 525
Size:  37.1 KB
Name:  20151217_022928.jpg
Views: 521
Size:  30.7 KB
Name:  20151217_022931.jpg
Views: 520
Size:  29.5 KB
Name:  20151217_022939.jpg
Views: 502
Size:  43.8 KB
 
Sponsored Links
  #2  
Old 12-16-15, 06:46 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,711
Received 1,180 Votes on 1,093 Posts
Welcome to the forums.

The two diodes in the red box are what convert the AC to DC. Can you take a nice closeup picture of the foil side of that board and post it for me ?

I'm trying to figure out what the part is with the pink ?

Name:  20151217_022928.jpg
Views: 457
Size:  34.1 KB
 
  #3  
Old 12-16-15, 06:58 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,523
Received 37 Votes on 34 Posts
Would that be a bridge rectifier?

Bud
 
  #4  
Old 12-16-15, 07:00 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,711
Received 1,180 Votes on 1,093 Posts
It could be Bud. I can tell better from bottom of board. The diodes may be zeners and not used as rectifiers.
 
  #5  
Old 12-16-15, 07:04 PM
V
Member
Thread Starter
Join Date: Dec 2015
Location: The Netherlands
Posts: 4
Received 0 Votes on 0 Posts
Name:  20151217_030000.jpg
Views: 446
Size:  41.1 KB

The pink ? is the power switch circled in blue on the picture. The 2 diodes are circled in red!

Hope this helps
 
  #6  
Old 12-16-15, 07:29 PM
C
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 2 Votes on 2 Posts
It looks like there are two more diodes the other side of the black blob, which makes sense since you need four diodes for a full wave bridge with no AC center tap.

So either the black blob is a small transformer to provide a center tapped AC for a full wave rectifier, or there are four diodes for a full wave bridge rectifier.

If there's not a transformer, then the diodes don't even need to be removed as long as the DC is correct polarity and the voltage allows for and extra diode drop or two.
 
  #7  
Old 12-16-15, 07:33 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,523
Received 37 Votes on 34 Posts
Ok, I see, it is a push button switch and perhaps 2 more diodes on the other side. I'll leave the rest to X.

Bud
 
  #8  
Old 12-16-15, 07:35 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,711
Received 1,180 Votes on 1,093 Posts
Since the "blob" is a power switch and there are four diodes.... CT is correct. You can just feed it with DC directly. Since it is full wave.... polarity is unimportant. Just need to figure out what voltage DC to send in. What voltage was the AC supply ?
 
  #9  
Old 12-16-15, 07:39 PM
V
Member
Thread Starter
Join Date: Dec 2015
Location: The Netherlands
Posts: 4
Received 0 Votes on 0 Posts
Thanks for the reply guys!

The adapter outputs 12Volt; 300mA

I maybe missing something, but I can only make out 3 diodes on the circuit.
 
  #10  
Old 12-16-15, 07:54 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,711
Received 1,180 Votes on 1,093 Posts
I'm looking at it now.... it looks like two diodes are used for a half wave supply. Then it looks like the single diode is a second supply.
 
  #11  
Old 12-17-15, 06:07 AM
V
Member
Thread Starter
Join Date: Dec 2015
Location: The Netherlands
Posts: 4
Received 0 Votes on 0 Posts
Where would you suggest to solder wires to the circuit?
 
  #12  
Old 12-17-15, 06:02 PM
C
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 2 Votes on 2 Posts
Well this gets more complicated if there are multiple supply voltages, and it looks like that's the case. VriendjeVenkel, if you have a multimeter, I suggest setting it to DC and measuring between common (That big hole/rivet above the power switch looks like a good place to pick up common) and the sides of the diodes that are not connected to the power switch. If you get 2 or 3 different voltages or polarities I think you are stuck using AC unless you want to provide all the voltages.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: