SmallNetBuilder Forums
Go Back   SmallNetBuilder Forums > Wireless Networking > General Wireless Discussion

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-19-2012, 04:14 PM
Radiolab Radiolab is offline
New Member
 
Join Date: Nov 2012
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Radiolab is just starting out
Default Cisco WAP321 - broken transistor repairment

Hi guys!

I have Cisco WAP321 working without any problems for couple months. Suddenly AP has gone away - no radio, no ping. Only LAN LED blinks according to broadcast network activity. I've opened AP and discovered that the problem caused by broken transistor Q1 in circuit of core (?) voltage DC/DC. This transistor is in SOT23-6 case and marked as 187G. There is no any info about partnumber. Also it's impossible to get any info about this circuit due to DC/DC controller is a part of Broadcom SoC and any datasheets are available only with NDA.

I've blown away this transistor and applied voltage directly from HP lab powersupply. Slowly increasing voltage and restarting AP I've made it to work on 1.8V (1.6V on the pcb due to wire dropout) but it's not stable. I think i should add more volts to get stable work, but it's a little bit dangerous.

So I want to ask somebody to help me. Please turn on your AP without top cover and measure the voltage between market point A and B (see attached picture). So I can put external DC/DC tuned to appropriate voltage and bring AP back to life.



Sorry for my English. Best regards. Dmitry.
Attached Images
File Type: jpg wap321_repair.jpg (69.0 KB, 13 views)
File Type: jpg ps_voltage.jpg (38.2 KB, 5 views)
Reply With Quote
  #2  
Old 09-23-2013, 02:00 PM
beny beny is offline
New Member
 
Join Date: Sep 2013
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
beny is just starting out
Default

@RadioLab I don't it's advisable to use external DC-DC unless you're completely sure that you're replicating the original signal exactly. Download the SMD code book, find out what the transistor code stands for. If it's a simple NPN transistor in SOT-23 package you can find any NPN transistor from either Fairchild Semiconductors or Motorola from farnell. It's easy to replace. If you don't have much soldering experience you can go to your nearest RadioShack and find someone to do it or you. It's better to get a simple OST-23 transistor replaced then having to deal with a board with multiple components malfunctioning.

montaje pcb

Last edited by beny; 10-01-2013 at 10:31 AM.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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 Off
HTML code is Off


All times are GMT -4. The time now is 02:26 AM.

Top 10 Stats
Top Posters* Top Thanked
RMerlin  401
stevech  156
thelonelycode...  151
L&LD  126
azazel1024  119
KGB7  86
jim769  80
DrTeeth  69
Adamm  65
speedingcheet...  61
RMerlin  4487
stevech  275
ryzhov_al  199
TeHashX  194
RogerSC  166
L&LD  163
joegreat  105
jlake  102
PrivateJoker  93
sinshiva  88
Most Viewed Threads* Hottest Threads*
Old Asuswrt-Merli...  31771
Old Asuswrt-Merli...  23588
Old ASUS...  22682
Old Beta Version...  17523
Old 'Heartbleed'...  14282
Old Linksys...  9411
Old Potential...  7929
Old Asus-Merlin...  7099
Old Groundhog...  6421
Old Linksys...  5703
Old Asuswrt-Merli...  218
Old Asuswrt-Merli...  176
Old Linksys...  144
Old ASUS...  125
Old Beta Version...  112
Old Potential...  98
Old Linksys...  79
Old Groundhog...  49
Old Asus router...  43
Old USB drive...  39



Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
© 2006-2014 Pudai LLC All Rights Reserved.