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LA 900 moble amp.

Discussion in 'Amplifiers' started by donemad, Feb 26, 2012.

  1. donemad

    donemad Active Member

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    Anyone know who makes this amp? I been looking for a sch-matic or drawing of the inside......Thanks for any help.


     
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  2. GLR

    GLR Keeping It Good Natured

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    I had one a few years back, was told it was made buy a guy in Ohio that is no longer in business.

    I am of no help at all.
     
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  3. mackmobile43

    mackmobile43 Jock Supporter

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    They are davemade copies if it helps
     
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  4. AudioShockwav

    AudioShockwav Extraterrestrial Admin Staff Member

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    1 2sc2290 driving 4 2sc 2879`s and dual fans on top there should be a led on the front of the Amp that says "heat" on it that will light when the heat sink gets too hot, and will also open the relays until the amp cools down.
    I think the 900 model had 1 or 2 large red power leads and a big bolt on the Back of the case for ground...
    If it is the amp I am thinking of a Guy named Steve built them here on the west coast, i think it is the same guy that built Pirate amps.....changed the name a few times.
    Some had a MRF 455 driving 4 2290`s some had a 2290 driving 4 2sc2879`s and so on depending on the model.
    TX 800, La900 and a few smaller ones.
    They were good amps IF you keep the dead key into the amp very low.
    The heat sink is very small for a Amp with that transistor set up, that is why it has two fans and the heat protection built in.
    The case is pop riveted on, and you have to be careful when drilling out the rivets so as to not damage the board or components that sit very close to the rivet holes, same thing when putting it back together, if the new rivets/screws are too big/long same damage.
    Lots of cores used in that amp, wrapped around the power leads, big Teflon coated wire, there is a lot going on inside that amp in a very small package.
    I have never seen a Drawing of the inside of that amp.
    HITECK REDNECK asked the same question some time ago and no results.
    See here.
    http://www.worldwidedx.com/general-cb-services-discussion/131752-transmit-800-a.html
    There is another thread here also that shows some pictures of the inside of the Amp if you search around a bit.

    Here are some Pictures of the 500 model built by the same guy.
    Thanks to pede69 for the Pictures.

    Good Luck in your Search.

    73
    Jeff
     

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  5. mackmobile43

    mackmobile43 Jock Supporter

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    Yup! 10 lbs of shit in a 5 lb bag, probably worked ok but too much on that heat sink.
     
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  6. AudioShockwav

    AudioShockwav Extraterrestrial Admin Staff Member

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    This will give you an Idea of the Heat sink`s used on the TX-800 as compared to a Texas Star 667V.
    The 667V is a 1x4
    1 2290 driving 4 2879`s
    the TX 800 is also a 1x4 2290 driving 4 2879`s
    The heat sink on the left is a 667, the one on the right is a TX 800
    ( sorry about the quality of the Pictures, these I took this morning with my cell phone, my good Kodak has died for some reason)
    The 667 is well know for running hot, and the 800 has an even smaller heat sink....I am sure this is why the builder put dual fans on it and the over temp protection.
    Also note how T/S has the 4 2879`s spread across the heat sink, were as the 800 has all 4 transistors stacked next to each other.
    I am not saying that the 800 is a pos, what I am saying is that the 800 needs to be run very carefully to avoid overheating it they were made for a very low dead key and I would not swing more than 12 or 15 watts into one......that is why I have this heat sink.
    I gutted it to rebuild another TX 800 that I got on flea bay, and sold it.
    I do NOT like Amps with built in drivers
    It was in a bunch of stuff i bought when a radio shop here closed, this amp was fried inside, who ever owned it by-passed the temp sensor so the amp would keep running....I "guess" he got tired of the relay tripping out when the amp was overheating....the "more power syndrome "

    73
    Jeff
     

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  7. donemad

    donemad Active Member

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    Hi, Jeff...been a while, I have not heard from.. but is this the same thing I was speaking of? Its a LA 900 is all I know.......
     
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  8. AudioShockwav

    AudioShockwav Extraterrestrial Admin Staff Member

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    It is as far as I know.. The TX 800/LA900 were on the same heat sink as the TX 500, but the 800/900 had 2 fans on it, mounted on brackets above the amp and came on when you turned on the amp, the Face plate and switches were the same......can you give us a picture of the Amp that you have?
    Dx has been good here on the west coast, have you been on the radio?

    73
    Jeff
     
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  9. donemad

    donemad Active Member

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    Yes Jeff, I talk to wesy coast all the time, John Denver with the cardboard crown.......haha. Sorry no pics. Thank you very much Jeff. oh, I,m looking for 2 2312 finals if you can help...
     
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  10. AudioShockwav

    AudioShockwav Extraterrestrial Admin Staff Member

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    PM sent.
     
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