El cheapo amp scam!!!! - Page 1
Forum section: electronics / repair

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 12:39:08 pm
content: A neighbor asked me to fix his amp complaining that it doesn't sound anymore. Told him to bring it to my workshop so I can try to fix it. It powers on but doesn't sound at all, so maybe there was something wrong on the main amp that prevents the relay to latch up. I opened it and I was surprised and stumbled upon seeing thisSome of the output trannies looked different than the others which was quite suspecting..hmmDue to curiosity I unscrewed the amp board so I can look closer at the top and solder side and this are what I've found. The are no solder joints on those weird looking transistor, short unsoldered legs and its bullshit! Its not a real component.. Its just a three legged plastic thing that marked with the same part number as real ones.[/urlObviously it's plastic!!!![url=http://postimg.org/image/vi7smoqv9/full/]The front endSo to speak the whole thing is a crap. It worked again after I replaced the shorted pair of power output transistors and flame proof resistors on one channel. Tested it for a couple of hours and its good to go.I wonder why the government permits such scam to happen here or why they allow such products with fake (or dummy parts) to be sold. It's seems to me that scamming was quite a game here. Does this this kind of things (consumer electronics scam) do happen in your country? Please let us know. Perhaps you have some story to tell..Best regards,Elex

author: djQUAN
author_rank: Frequent Contributor
timestamp: October 04, 2015, 12:49:43 pm
content: "I wonder why the government permits such scam to happen here or why they allow such products with fake (or dummy parts) to be sold. It's seems to me that scamming was quite a game here."You're in the Philippines. Where the government only cares about their own pockets and nothing else.

author: BradC
author_rank: Super Contributor
timestamp: October 04, 2015, 12:50:06 pm
content: It's everywhere, but that is a particularly nice example.

author: wagon
author_rank: Frequent Contributor
timestamp: October 04, 2015, 12:50:41 pm
content: It's common enough. Look up 'white van scam'. I'm pretty sure Dave did a video on it, too.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 12:53:20 pm
content: Quote from: djQUAN on October 04, 2015, 12:49:43 pmHell yeah! Corruption over rules everything and its sad.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 12:59:19 pm
content: Quote from: wagon on October 04, 2015, 12:50:41 pmYeah I saw that "white van scam" video. I wonder if this kind of scams do happen on EU countries and US states..

author: mikerj
author_rank: Super Contributor
timestamp: October 04, 2015, 01:53:46 pm
content: I don't quite understand why those 'dummy' devices have been fitted (since they can't been seen when the case is fitted) or why this would be considered a scam? They are clearly optional parts which are wired in parallel with the existing output transistor, with an extra emitter resistor.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 02:01:21 pm
content: Quote from: mikerj on October 04, 2015, 01:53:46 pmIt was quite obvious that those "dummy trannies" were fitted to look as if there is a two pair output transistors installed on the unit. Actually the whole amp board can be seen above the case through the vent holes.

author: amyk
author_rank: Super Contributor
timestamp: October 04, 2015, 02:18:52 pm
content: TOBHISY instead of ToshibaThe traces look real though, so I suppose you could upgrade by adding real transistors in their place.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 02:26:55 pm
content: Quote from: amyk on October 04, 2015, 02:18:52 pmYeah funny brand marking..hahaThere's still a space for a one pair addition if the owner decides to upgrade it.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 04, 2015, 02:42:01 pm
content: Quote from: blueskull on October 04, 2015, 02:39:18 pmEven C5200/A1943 had been pirated by some unknown manufacturers mostly from China. Aren't you aware of it?

author: Kleinstein
author_rank: Super Contributor
timestamp: October 04, 2015, 07:28:53 pm
content: The C5200 / A1943 transistors are still a good choice - except for beeing prone to get a fake if you don't get them from a reliable source.Having such obvous fakes is funny - though the amplifier should work at low power and maybe higher impedance, at least until it breaks down. So if there it is not working any more, likely something else is broken.

author: Mashpriborintorg
author_rank: Regular Contributor
timestamp: October 05, 2015, 09:57:13 am
content: I have seen a white van scam IRL, at a market near me !He sells weird all-in-one speakers (speaker columns with integrated amplifier and radio - mp3 player) and DVD/divx players with "100 free great movies included"

author: Tim F
author_rank: Regular Contributor
timestamp: October 05, 2015, 10:12:24 am
content: Quote from: mikerj on October 04, 2015, 01:53:46 pmProbably not 'optional' in the original circuit designer's eyes. It's likely that this is a result of "lets try removing some parts and see if it still works" by the production line and then trying to make it look like they populated the board properly at a quick glance. If it even has a V-I limiter on the output stage i wouldn't be surprised if it's still configured for dual pairs of output devices and has contributed to the single pair being blown. The working transistors were likely fakes anyway, and wouldn't have held up to the abuse that the real deal would have.

author: G7PSK
author_rank: Super Contributor
timestamp: October 06, 2015, 01:57:03 pm
content: Are they fakes or just duds with the leads cut off.

author: djQUAN
author_rank: Frequent Contributor
timestamp: October 06, 2015, 02:11:37 pm
content: I'm wondering if the fake parts contain silicon in them or just a plastic case with cut leads and nothing else.

author: elex_enthusiast
author_rank: Regular Contributor
timestamp: October 06, 2015, 02:27:42 pm
content: Quote from: djQUAN on October 06, 2015, 02:11:37 pmJust barely plastic..not a real part.. As I said it's a dummy transistor.

author: SteveLy
author_rank: Regular Contributor
timestamp: October 06, 2015, 02:32:41 pm
content: The kitsch fonts on the front panel are a dead giveaway. Still, the fake bolted on components are something special.

author: Gyro
author_rank: Super Contributor
timestamp: October 06, 2015, 07:47:02 pm
content: Might just be enough to fool your average HiFi magazine reviewer!

author: jancumps
author_rank: Unknown
timestamp: October 06, 2015, 07:54:20 pm
content: But why go through all this effort, and then not soldering the part?It has the pins, the PCB has the traces. Everything is mounted - and then they don't solder it. It's almost more work than just soldering it in ?!#@@

author: Gyro
author_rank: Super Contributor
timestamp: October 06, 2015, 08:04:28 pm
content: Those are fairly pricey output devices, the PCB was presumably originally designed to take them.