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 Sspa repair 
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Post Sspa repair
Hi guys, just accidentally put 50 watts into my Benos LPM144-25-180, is it repairable? What I mean is, are the components obsolete in side it. There is a sticker saying BERYLIUM OXIDE, TOXIC!!! Is there hope for the amp??

Thanks. Nick. 2E0BPU.


Thu Nov 20, 2014 1:34 pm
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 Sspa repair 
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Post Re: Sspa repair
Nick wrote:
Hi guys, just accidentally put 50 watts into my Benos LPM144-25-180, is it repairable? What I mean is, are the components obsolete in side it. There is a sticker saying BERYLIUM OXIDE, TOXIC!!! Is there hope for the amp??

Thanks. Nick. 2E0BPU.

The BERYLIUM OXIDE, TOXIC warning will relate to the power transistors.
If the top splits off the chemical will be released.
If I remember correctly, it's an accumulative poison that your system doesn't pass.
We used to seal old transistors and dispose of in hazardous waste.

It should be easy enough to check if the devices, or an equivalent, are still available.

Cheers

Tony

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Thu Nov 20, 2014 1:52 pm
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 Sspa repair 
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Ok thanks for the reply, I think the transistor has blown so i need to find a new transistor or 2 for the next time. So I need to find a SD 1441 M25, any ideas where to start looking as the transistor is probably over 15 years old.

Thanks. Nick.


Fri Nov 21, 2014 12:43 pm
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 Sspa repair 
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Post Re: Sspa repair
Be prepared to pay through the nose!
These are obsolete components, and as such many normal outlets no longer stock them.
Then what happens is stock is accumulated and stashed by "obsolete component suppliers", who basicaly "sit on them" stashed on the shelf, until someone makes a request, and often the price reflects the rarity!
Like these:
http://www.advancedsemiconductor.com/cg ... ubmit.y=14
Now when people ask you to "apply for a price", as oposed to specifying a price, usualy means they have quite a few, but they prefer a bulk purchase, and if you only want a "couple" they will charge a premium price!
A quick search didn't bring up too many with any stock of them at all, and those that did have some were overseas!
May be worth doing some cross referance, and finding a device that is commonly available that is reasonably compatible in physical and electronic characteristics, and doing a mod job!
I had an old MM 100 watt PA that used an obsolete device, sure I found one eventualy, but at an asking price of £80, to repair a linear that cost £10, it went into that great gizmo dustbin in the sky!
Shame if you can't find one or an equivelent, as they are quality linears! (Unlike the MM!)

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Fri Nov 21, 2014 1:06 pm
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 Sspa repair 
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Post Re: Sspa repair
Ok Dave, this is what I expected, there are some on e-bay for £32, BUT, not sure if this is exactly right, I can live with £32.
http://www.ebay.co.uk/itm/SD1441-TRANSI ... 4ad2066816

All the best. Nick.


Fri Nov 21, 2014 1:32 pm
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 Sspa repair 
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Post Re: Sspa repair
best open up the pa before you order to check its the correct package

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Its not the class of licence the amateur holds thats important but the class of bias the prat applies to his amplifier


Fri Nov 21, 2014 1:40 pm
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 Sspa repair 
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Post Re: Sspa repair
it says SD 1441 M25 on the device so probably not


Fri Nov 21, 2014 1:47 pm
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Post Re: Sspa repair
Neill wrote:
best open up the pa before you order to check its the correct package

As neil says, the original, as oposed to an electrical spec equivelent, might not occupy the same package configuration!
It physicaly looks the same, heres a link to the original spec sheet:
http://www.digchip.com/datasheets/downl ... how=inline
At £32 not too bad, but before you buy cross referance the actual specs.
Also what are the symptoms, does it still "RF" switch but no/low output, or does it no longer respond to RF switching?
If the latter the damage could be to RF switching circuitry, while the device itself is still OK, if the former most likely the main device itself has failed!
Hope this helps.
By the way the M25 bit is a manufacturers code, the fact the replacement shows different is not unusual, its the "SD1441" bit, and quoted specs, thats important!

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Fri Nov 21, 2014 1:52 pm
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One other thing if you decide to purchase this replacement device, when you come to fit it do NOT rely on printed lettering for orientation of the device!
Meter it out to ensure you have the base, emitter and collector tabs the right way round!
I say this because I ordered a replacement for an SD1446, that came with the printed writing 180 degrees the other way!
So if I had simply plonked it in without checking, print to print, it would have been wrong!
Heres the layout pin connections, a simple diode check on a transistor checker, or diode check multimeter, is advisable, to ensure you don'y have it 180 degrees misplaced!
Attachment:
untitled.JPG
untitled.JPG [ 10.78 KiB | Viewed 2744 times ]

NOTE: Simply viewing "Physicaly" the centre collector tab, is slightly slimmer than the centre base tab!
Also use a decent dollop of heatsink compound, and tension/tork the two mounting pins equally!

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Been there and got the T shirt, sadly like the T shirt the memory of it has long since faded, gone rather tatty, and finally been consigned to the bin!


Fri Nov 21, 2014 2:25 pm
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 Sspa repair 
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Post Re: Sspa repair
Ok thanks, i have looked at 4 data sheets from different manufactures and they look the same as the one you sent me, more reading is needed, but thanks for your time and help.


Fri Nov 21, 2014 6:18 pm
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 Sspa repair 
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Nick wrote:
Ok thanks, i have looked at 4 data sheets from different manufactures and they look the same as the one you sent me, more reading is needed, but thanks for your time and help.

Not a problem they look perfectly compatible to me, and as long as they are replaced with the right orientation, and you check bias post fitting, should get this decent "old girl" back up and running! :D
BNOS stuff is too good to scrap! ;)
Still have a 30 amp PSU, and a couple of linears for 6 meters and 70 cms built by them, and no plans to change them, they do what they say on the tin! :good:

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Been there and got the T shirt, sadly like the T shirt the memory of it has long since faded, gone rather tatty, and finally been consigned to the bin!


Fri Nov 21, 2014 6:29 pm
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 Sspa repair 
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The BNOS linear is very hi quality, the heat sink is massive, it is twice the size of my sommerkamp sla200, the whole linear is about 3kg in weight, at 50 watts FSK441 into a dummy load it dose not even get a bit warm, this is why i want to save it from the bin.
Again thanks for your advice and help.

73 de Nick. 2E0BPU.


Sat Nov 22, 2014 9:23 am
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 Sspa repair 
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I have the circuit drawings if any wants them.


Sat Nov 22, 2014 10:11 am
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This place is slipping he's a 2E0 and he blew up his amp come on guys attack :D

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Sat Nov 22, 2014 10:26 am
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ei2glb wrote:
This place is slipping he's a 2E0 and he blew up his amp come on guys attack :D

An easy mistake to make for anyone Trevor! :D
I would love to say I have never done it myself, but unfortunately I have! :D
As to power levels and licence class, when it comes to technical repairs, I never question what was being used, just happy to try and help out, having been in the head in hands "damn I've blown it" situation myself! :D
Not a nice feeling!
I hope the device off E-bay, which is a decent price to be honest, gets his old faithful back up and running!
I am tempted to buy one myself, as I have a linear with that particular device in it for two meters, not a BNOS, but same device, and now getting on a bit in age, and a spare wouldn't go amiss! :good:

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Been there and got the T shirt, sadly like the T shirt the memory of it has long since faded, gone rather tatty, and finally been consigned to the bin!


Sat Nov 22, 2014 11:05 am
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