Biema Alpha Line Array Repair : No Schematics and Someone Has Looked At This Before

[@LearnElectronicsRepair]

*Thanks to a subscriber I was emailed this link to Elektrotanya and downloaded all the schematics but unfortunately none of them match the amplifier I am trying to repair. Mainly these are class A/B amplifiers where as mine is class G. If anyone wants some Biema schematics (free) here is the link* elektrotanya.com/showresult?what=BIEMA&kategoria=All&kat2=All

[@chillidogkev]

Watching and listening to Richard as he analyses, disects, discovers and understands the problem he is dealing with is absolutely top notch. His style and delivery of the content is outstanding and it's what puts him at the top of the pile for this type of video in my opinion 10/10.

[@jonathanrose456]

Some of these style line arrays are driven by stereo amps in bridge mode. Smaller amplifier manufacturers will sometimes provide the schematic if asked nicely to their customers service department

[@davidroth4514]

Looks like a class G or H. To me . Might be in bridge configuration as well ! I have been watching and enjoying for some years now ! Thank you for sharing your work and knowledge with us !

[@electronicengineer]

The burnt resistor looks like it is working together with the capacitor next to it as a Zoebel network. The other channel has the same resistor with capacitor Zoebel network, and you can just read the bands on the non-burnt resistor. Fred

[@andymouse]

I think your right and that wouldn't stop it working unless shorted ?

[@Lightrunner.]

Mosfet....Mosfet....Mosfet..🤣🤣🤣🤣🤣

[@matthewseymour5165]

Look forward to the follow up

[@Dutch_off_grid_homesteading]

Heya, yes that is a issue wen you don't have schematics and the color code is burnt. but the way you measer the resister could be good

[@sastromo]

That karaoke as BGM :D hehehe

[@ralphj4012]

Try the Biema FW series schematics (the FW-2400 has chunks missing but may be close to what you have, or not).

[@pauldery7875]

Great video Richard, I was wondering what model Fluke your using, Paul, USA.

[@justmc62]

Wow.. That PowerCon connection would definitely confuse me for a SpeakOn connector. Guess I'm not as versed with equipment outside of North America. Thanks for sharing your knowledge as always !

[@radioflyer2030]

VERY common connector on arena / stadium / festival / tour grade sound equipment **IN** North America, and all over the world. Also super common on DMX stage lighting because of the daisy chain feature. Great, unless the locking tab gets ripped off by brutal stage hands. Then they are worse than useless. Luckily, they are rarely molded on to the cable like IEC-C13 are, so field replaceable with a screwdriver.

[@LearnElectronicsRepair]

Well it won't confuse you now if you see one 😁

[@Daniel-OConnell]

Do I understand correctly that at 54:00 you are saying that the speakers are driven in push pull like an old valve radio?

[@warwickbunn1250]

As you have the add or web page for the actual item, are there any contact details for the manufacturer, so you could ask if they can provide a schematic ? Although you seem to be getting to grips with it now. Good effort. Looking forward to the next installment 😀

[@davidhollfelder9940]

You probably want to visit this customer, and make a list/inventory of his equipment, so you can be better prepared for his repair jobs.

[@davidroth4514]

I would guess that it is either a 10 or 22 ohm resister !

[@LearnElectronicsRepair]

That's my best guess too. Thanks David

[@thulinp]

If the resistor is in parallel with that coil, it's sure to be 10 ohm like the other one, and also: a probable cause for it burning: bad solder connection on the coil. See elektrotanya Biema BF600. This has a single 10ohm in paralell with a coil on the output.

[@LearnElectronicsRepair]

The two intact 10 ohm resistors are in parallel with the coils. The burnt one is not. From the results when I tried to test it I think it is likely to be somewhere in the range of 15-22 ohms but it is just an inspired guess. I'm also concerned why it would burn up if it is in series with a capacitor which looks to be the case, unless it also goes somewhere on the other side of the board which is hard to get to.

[@thulinp]

@@LearnElectronicsRepair Biema BF600: see RJ19. If it's connected like that, oscillation comes to mind

[@k3ggaming926]

Another long video that doesn’t have ending lols😂😂😂😂😂

[@LearnElectronicsRepair]

True but it will have a sequal 🙂

[@LearnElectronicsRepair]

@andrew_koala2974 oops 🤐

[@maebeans]

so it's a bridge mode amp by the sounds of it?

[@maebeans]

yep, as soon as u couldn't find the connection from the other speaker connection to ground i got it

[@Arachnoid_of_the_underverse]

Its going to be difficult as you cant test it without reinstalling back into the casement onsite.

[@RTBNL]

Just use a load resistor on the output as a dummy load.

[@Manticore1960]

I can't get my head around the readings of that ctu 36s double diode. You measured it more than once in the video while it was in circuit & it definitely read O/C. There is nothing on the board that can make a component read O/C while on the board, yet read normally when desoldered. Makes no sense at all. btw...the double diode on the other side of the board is also soldered onto extension wires.

[@LearnElectronicsRepair]

Broken solder joint to the center extension wire. When I measured it in circuit I didn't probe the device legs just the soldered area

[@Manticore1960]

@@LearnElectronicsRepair It looked like it had masses of solder on the centre pin though. That's what confused me. But your explaination is the only logical reason. 👍

[@photohounds]

Very common for off-brand to have no info. Often a Throwaway item as far as the maker is concerned...

[@LearnElectronicsRepair]

And yet this comes from professional and no doubt expensive equipment.

[@LearnElectronicsRepair]

@andrew_koala2974 What maker?

[@dcocz3908]

@andrew_koala2974 Ergo it's the 10OHM resistor, sleep on it and see