replacing voltage regulator a8805 - 2.4ghz Amplifier.

Discussion in 'General Electronics Chat' started by dilip_microwave, Aug 21, 2011.

  1. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
    Hi all,

    I bought a 2 watt 802.11g wireless amplifier and I was sent the wrong power supply. The power supply was 12V 1A supply but i believe it should have been 6volt 2AMP.
    It seems it as blown the regulator a8805 / AEF02 , it looks burnt. Is there a way to bypass this regulator if I can supply a supply of 6 volts ??

    Or do you know of en equivalent regulator i can buy to replace it ??

    Many thanks.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,741
    759
    show us the parts and burned components
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Here is a datasheet for the a8805:
    http://www.datasheetcatalog.org/datasheet/ame/ame8805.pdf
    In the "/ AEF02" suffix, the leading "A" means that the output of the regulator is 3.3v. If you jumpered across the regulator and fed 6v to the input, you would let the smoke out of the components past the regulator.
    The "F" suffix means an SOT-89 package.
    Digikey carries several regulators that might be suitable, if the pinouts are the same.
    AP1117Y33G-13
    AP7215-33YG-13
    AP1115BY33L-13
    AP1117Y33L-13
    I didn't check their datasheets; I'll leave that up to you.
     
  4. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
    Thank you very much for your reply. Do you think I can run a bypass on it and make it work of a usb cable ??? I believe USB runs from 3 volt.

    Thanks again.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    USB is 5 volts; don't use it.

    According to the datasheet SgtWookie provided, the recommended input to the regulator is 4.5 to 5.5 volts with an absolute maximum of 8 volts. The output current is limited at 800ma; thus, even though USB voltage might serve as an input to the regulator, the 500ma of current on a USB line would be insufficient.

    What is the brand and model number of the amplifier?
     
    Last edited: Aug 21, 2011
  6. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
    Details on the amplifier are quite limited. But The information below is what I pulled from the ebay listing. My particular amplifier is for the 2 watt version. The power for the amplifier below shows 5 to 7Volts working voltage so im unsure what I should try. Next.

    This link below shows a similar amp and it shows the circuit board.

    http://www.ebay.co.uk/itm/2w-WIFI-8...=300361622221&ps=63&clkid=2222353253250259104

    Again very much for your help.


    • Operating range : 2400-2500MHz
    • Operating mode : Bi-directional, half-duplex Time Division Duplex Senses RF carrier from Transmitter and automatically switches receive to transmit mode
    • Connector Type: SMA Receptacle (50 ohm)
    • Transmit gain : 15dB
    • Optimal Input Power: 9~13 dBm
    • Receiver Gain: <12 dBm
    • Noise Figure: 3.5dB typical
    • Frequency Response: ± 1dB over operating range
    • Power Adaptor: 5~7V /DC 105~240V for AC Adapter
    • Operating Temperature: -20 to 70 °C
    • Operating Humidity: Up to 95% relative humidity
    • Material: Cast Aluminum
    • Package Weight: 560g
    • Dimension: 7.8cm(L) x 5.6cm(W) x 2.9cm(H)
     
  7. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    If the seller furnished the wrong voltage power supply, he/she should replace the amplifier and power supply with a new one under the terms of the 12 month warranty. If you can't/don't want to get a replacement, then you will have to repair the one you have either by finding and replacing the damaged component(s) on the PCB, or by building/buying an outboard 3.3v supply and wire it into the PCB. Neither of those repair options would appeal to me. If the damage was caused by the seller, I would send it back for a replacement under warranty.
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    Do you have a licence to use the high power amplifier for the wfi ?

    The FCC states that the EIRP may not be greater as 1 Watt:

    This is a quote from this page:
    http://www.wi-fiplanet.com/tutorials/article.php/1428941

    Bertus
     
  9. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
    I am currently in dispute with the seller over this issue. But i'm hoping I can get a refund but also fix the amplifier.

    Could you guys give me a little insight into bridging the regulator ? I can easily get an external supply but bridging it may be a little more difficult.

    I am unsure if its safe to bridge without uncoupling the external support resistors for capacitors that regulator may use.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Well, why don't you trace out the circuit, and post it so that we can see how it is current ly wired up? Without that, all we can do is guess. Guessing = smoking parts.
     
  11. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
    Hi,
    thank you all for your replies. I have attached a picture. I will do my best to describe it

    To the left of U2 is where the regulator AEF02 was soldered.

    To the far bottom right of circuit board is where the DC power supply comes in.

    I believe it would be a simple matter of bridging the far right connector to the middle pin where the regulator was once soldered. Once i have the 3.3Volt connected.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Well, the pads for U2 definitely need to be cleaned up. If you have some solder wick and a bit of liquid rosin flux, that should do nicely.

    If you have some tin/lead solder, you will probably find that it will be easier to de-solder it if you add some tin/lead solder first, as much of the lead-free stuff needs to be heated quite a bit more to melt. Adding the tin/lead solder beforehand brings the melting temp down.

    From the datasheet and what I can see of the board, the input pin was on the left, and the output on the right.

    However, there is something that might be another regulator; U17. You need to find the datasheet for that and make sure.
     
  13. dilip_microwave

    Thread Starter New Member

    Aug 21, 2011
    6
    0
Loading...