Is The IC Faulty Or Is It Something Else PART 2 : Basic 400 Bi Amp Active Speaker Repair

[@darrenbird2526]

6:15 pm Wednesday night in Tasmania Australia and I'm spoilt with a LER Video to be able to sit here and eat my Steak eggs and chips, watching my favourite show! Thanks Rich!

[@LearnElectronicsRepair]

Thank You 😀

[@izzzzzz6]

Use the Mr Solder fix technique. Take some solid copper wire and bend it to fit the legs of the device being removed. Flood it and it simply drops out. Also those super wide tips are available. I didn't have the station required but i bodged it into an old soldering iron handle and wired it up to a bench supply. Also works a treat.

[@harrilumme1875]

When probing the op amp pins there were differences in the input pins(32:10). There were clearly units which were visibly wired as unity gain buffers and there the inverting inputs are connected to outputs. That explains the different behaviour of the pins.

[@andymouse]

:)

[@Hellhound604]

Lots of valuable tips for beginners re the vacuum tool, Richard.👍👍👍 next time you should include a section about dismantling the tube/spring assembly and cleaning the whole assembly and show the dirty filters after a time… (btw, those white IKEA pads without glue, that you put under the legs of chairs works well as filters if you trim them a bit)

[@badboydas]

The allen key star is called a Torx. Another great vid cheers.

[@Dutch-linux]

A good way to start the day by watching LER thanks Richard

[@franciscofernandes7526]

It is worth taking ideas from the well experienced

[@Lightrunner.]

Hi Richard 🤗 Your solder skils are getting better and better 👍👍 The JRC insn't new,, there are a very old electronic company 🤣🤣. I miss your oscilloscope for this repair😭

[@paulstaf]

I have seen a technique to desolder a chip where you take a copper wire and route it over all the pins and flood solder over it and the pins all at once and then the solder melts on all the pins and the chip will fall right off. Then you clean up the extra solder with a solder wick.

[@analoghardwaretops3976]

That was the first method to learn that was also part of the training.....if one can do that easily..then with proper tools its always easy

[@mechanoid5739]

How weird! I ordered that exact de-solder tool from Radio Spares yesterday and it arrived today. It obviously had the RS branding on it but other than that, it is exactly the same.

[@garypoplin4599]

2:22 - According the amplifier’s datasheet you showed in part one, this mica cap is across the inverting and non inverting inputs to this amplifier. I don’t know of an amplifier circuit where a cap is placed across the inputs.

[@LearnElectronicsRepair]

@garypoplin4599 It does show that cap in the typical application in the datasheet. The description says 'Reduces the gain (bandwidth of the amplifier) at high frequencies to avoid quasi-saturation oscillations of the output transistor. The capacitor also suppresses external electromagnetic switching noise created from fluorescent lamps.' The datasheet says the cap is optional. pdf1.alldatasheet.com/datasheet-pdf/view/558418/TI1/LM3886T.html

[@garypoplin4599]

@@LearnElectronicsRepair I just learned something else from you. Thanks. I’m building a μA adapter to use on my DMM to get around the high burden voltage of my meter inherent in low current readings. With the adapter connected, the current is read in mV per nA, μA, or mA depending on the adapter setting. Maybe I should incorporate 220 puff caps into the design. JAT

[@mikebond6328]

I’m going to build a solder vacuum using various parts from solder suckers, a water cooler, etc. I have all the parts, just need to build it.

[@cliff_hewitt]

Looks like the thermal camera/meter shows the max and min temperatures to the right of the big yellow temperature reading. Max is red, min is green. You won't have to hunt with the center crosshairs that way.

[@tiggydorset9041]

I bought 3 amp chips from a seller for a repair job (1 for the job, 2 for stock). In the same package were the 3 chips, but one was different. The etching/writing was not quite the same as the other 2. It turns out this chip was fake when the other 2 were good (I compared meter readings which were different from each other); same package from the same seller. Its safe to assume that these chips are faked, so be wary.

[@GiC7]

Thanks

[@Mark_C1]

@learnelectronicsrepair hey Richard. I have a load of ic’s, op amps, 555 timers, Schmidt triggers, hex fets that sort of thing I bought as a job lot. I could send you over a list of what I have and if any of them are any good to you I don’t mind saving them until your back in Blighty next and send them to you. All original new old stock so should be reliable and I won’t want a lot for them either 😊

[@garygranato9164]

D35 looks iffy

[@LittlePetieWheat]

Have you seen solder sucker irons? e.g. YIHUA 929D-V Electric Vacuum Desoldering Iron £15

[@LittlePetieWheat]

I see there are now some cheap pumped ones for £30

[@mikebond6328]

I ordered one for $9US in the US. It had a US 120 volt plug. I plugged it in and it would never get hot enough to melt solder. I then read the instructions and it was rated for 240v. I tore it down and removed about half of the heat element and it works fine. The spring loaded pump is not great. I’m going to attach a vacuum pump to it and see how that works.

[@Diebog]

Low melt solder would be ideal here.

[@LearnElectronicsRepair]

I made a couple of comparison videos for solder suckers, including that type, one video was desoldering through hole components and the other to clean PCB holes with the component already removed. You may be interested in the results, the tools did not perform the same for the different tasks kzbin.info/www/bejne/rHW0m3qbZsaMppo kzbin.info/www/bejne/e6Cvkmybl8-qfbc