J
JW
Guest
http://www.eevblog.com/forum/chat/mj15025-transistors-wrong-polarity!!!!!!!!!!/
You can guess from where...
You can guess from where...
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Guest
On Friday, August 5, 2016 at 1:48:36 PM UTC-5, JW wrote:
I buy things like that from Digikey.
http://www.eevblog.com/forum/chat/mj15025-transistors-wrong-polarity!!!!!!!!!!/
You can guess from where...
I buy things like that from Digikey.
C
Cursitor Doom
Guest
On Fri, 05 Aug 2016 12:40:44 -0700, jurb6006 wrote:
What fakes??
On Friday, August 5, 2016 at 1:48:36 PM UTC-5, JW wrote:
http://www.eevblog.com/forum/chat/mj15025-transistors-wrong-
polarity!!!!!!!!!!/
You can guess from where...
I buy things like that from Digikey.
What fakes??
Guest
> What fakes??
Where have you been ? Fake semiconductor have been a cash cow for Chinese (and other) companies that are not doing all that well. Or to just change the number on it.
Also, there are some ICs they can make a fortune on, for example the Technics STKSVI ones. Talk a hundred bucks apiece. These days, don't count on getting any good STK anything. At least not for audio. There are alot of STKs out there that are for switched mode power supplies and a few other things, you might be able to find a good one of them once in a while, but in audio it is much less likely.
Where have you been ? Fake semiconductor have been a cash cow for Chinese (and other) companies that are not doing all that well. Or to just change the number on it.
Also, there are some ICs they can make a fortune on, for example the Technics STKSVI ones. Talk a hundred bucks apiece. These days, don't count on getting any good STK anything. At least not for audio. There are alot of STKs out there that are for switched mode power supplies and a few other things, you might be able to find a good one of them once in a while, but in audio it is much less likely.
A
Andy Burns
Guest
jurb6006@gmail.com wrote:
Hmmm, did I put my old SU-V4X in the loft, or chuck it in a skip?
there are some ICs they can make a fortune on, for example the
Technics STKSVI ones. Talk a hundred bucks apiece. These days, don't
count on getting any good STK anything.
Hmmm, did I put my old SU-V4X in the loft, or chuck it in a skip?
P
Phil Allison
Guest
jurb...@gmail.com wrote:
** Think you need to put a comma after "What" and read the post as:
" What do you mean, fakes from Digikey ?? "
.... Phil
What fakes??
Where have you been ?
** Think you need to put a comma after "What" and read the post as:
" What do you mean, fakes from Digikey ?? "
.... Phil
Guest
On Sunday, August 14, 2016 at 11:06:19 PM UTC-5, Phil Allison wrote:
WTF are you trying to say here ? Rephrase it if you would.
jurb...@gmail.com wrote:
What fakes??
Where have you been ?
** Think you need to put a comma after "What" and read the post as:
" What do you mean, fakes from Digikey ?? "
... Phil
WTF are you trying to say here ? Rephrase it if you would.
P
Phil Allison
Guest
jurb...@gmail.com wrote:
** CD was asking if you bought fake MJ15024/25s from Digikey.
Cos your one line post seemed to say that.
..... Phil
Phil Allison wrote:
What fakes??
Where have you been ?
** Think you need to put a comma after "What" and read the post as:
" What do you mean, fakes from Digikey ?? "
WTF are you trying to say here ? Rephrase it if you would.
** CD was asking if you bought fake MJ15024/25s from Digikey.
Cos your one line post seemed to say that.
..... Phil
Guest
"Hmmm, did I put my old SU-V4X in the loft, or chuck it in a skip? "
Does not matter, it will be the latter.
On speakers that were right for them, they sounded good. But on most there really was no difference.
The main thing you get by biasing a transistor amp harder is damping factor at really low power levels. I got a PL400/2, damping factor 1,000. You can hear the difference, but not much. And the amazing part is they run the outputs in class B, you get the sound from the drivers mostly below a watt or two. Probably going to sell that thing, got a ton of blown speakers in the garage. Well not really. Haven't taken them out there yet to go with the other ones.
Guest
On Monday, August 15, 2016 at 1:56:49 AM UTC-4, Phil Allison wrote:
God, I hope not. I have not gotten a bad semi from DigiKey or B&D (http://www.bdent.com/)
B&D is the only place to get those Sony MCD smps controllers that don't literally explode on turn on and Sanyo STKs for PTV convergence outputs. Fortunately, those TVs are pretty much obsolete but I still do about 6 PTV convergence jobs a year.
jurb...@gmail.com wrote:
Phil Allison wrote:
What fakes??
Where have you been ?
** Think you need to put a comma after "What" and read the post as:
" What do you mean, fakes from Digikey ?? "
WTF are you trying to say here ? Rephrase it if you would.
** CD was asking if you bought fake MJ15024/25s from Digikey.
Cos your one line post seemed to say that.
.... Phil
God, I hope not. I have not gotten a bad semi from DigiKey or B&D (http://www.bdent.com/)
B&D is the only place to get those Sony MCD smps controllers that don't literally explode on turn on and Sanyo STKs for PTV convergence outputs. Fortunately, those TVs are pretty much obsolete but I still do about 6 PTV convergence jobs a year.
Guest
"** CD was asking if you bought fake MJ15024/25s from Digikey.
Cos your one line post seemed to say that.
.... Phil"
OK, I'll clarify.
I buy shit like that from Digikey and have never had a problem.
Guest
>"God, I hope not. I have not gotten a bad semi from DigiKey or B&D >(http://www.bdent.com/) "
Me too. I found B%D parts to be good. More expensive, but if your time is valuable it is worth it to only have to change it once.
While I am good enough to change a convergence IC a bunch of times without damaging the board, sometimes it take time to get to it. Plus, some boards are fragile and the pads seem like they just want to come off. After the second time sometimes you are on thin ice no matter how good you are.
I have seen some really awful soldering. Some of these people should not be techs. I learned because I don't want to repair lifted pads and broken traces on the board. One boss told me that I use more solder wick than anyone else and I retorted "Yeah, and I've seen their work". A few minutes to change the IC and then an hour to clean up the mess they made out of the copper on the board. And that is one of the reasons I made twice as much as them. That and being the goto guy. Shit, we had one guy who was in electronic engineering school who didn't know the difference between a diac and Zener diode.
And none of them understood the concept of a convergence amp. It is sorta a transconductance amp, it converts voltage to current. It was justy about the only way they could do it.
Know what impressed me ? Zeniths. We had one for a while, no convergence outputs, strictly a passive circuit with caps and coils. Converged just fine. Actually had a pretty good picture. In fact one thing notable about that one was the sound, the sound was excellent. Found out one time while cleaning it that the screen acted as a passive radiator for the bass. I don't remember the board set but those were the ones where the high value resistors went bad and the G2 went sky high and burned the CRT phosphors as they went into shutdown. We had to put two CRTs into it, which is why we got it cheap..
Me too. I found B%D parts to be good. More expensive, but if your time is valuable it is worth it to only have to change it once.
While I am good enough to change a convergence IC a bunch of times without damaging the board, sometimes it take time to get to it. Plus, some boards are fragile and the pads seem like they just want to come off. After the second time sometimes you are on thin ice no matter how good you are.
I have seen some really awful soldering. Some of these people should not be techs. I learned because I don't want to repair lifted pads and broken traces on the board. One boss told me that I use more solder wick than anyone else and I retorted "Yeah, and I've seen their work". A few minutes to change the IC and then an hour to clean up the mess they made out of the copper on the board. And that is one of the reasons I made twice as much as them. That and being the goto guy. Shit, we had one guy who was in electronic engineering school who didn't know the difference between a diac and Zener diode.
And none of them understood the concept of a convergence amp. It is sorta a transconductance amp, it converts voltage to current. It was justy about the only way they could do it.
Know what impressed me ? Zeniths. We had one for a while, no convergence outputs, strictly a passive circuit with caps and coils. Converged just fine. Actually had a pretty good picture. In fact one thing notable about that one was the sound, the sound was excellent. Found out one time while cleaning it that the screen acted as a passive radiator for the bass. I don't remember the board set but those were the ones where the high value resistors went bad and the G2 went sky high and burned the CRT phosphors as they went into shutdown. We had to put two CRTs into it, which is why we got it cheap..
A
Andy Burns
Guest
jurb6006@gmail.com wrote:
I bought Mission 707 speakers at the same time as the amp
>got a ton of blown speakers in the garage.
The 707s died from rotten rubber gaskets, and got chucked before I found
you could buy refurb kits for them, still have the stands and original
cardboard boxes for them though!
<later>
Just ventured up into the loft and the amp (actually the SU-V2X) is
there in its original box, ebay says good examples sell for ÂŁ40-ÂŁ60, so
it can stay there.
Andy Burns wrote:
"Hmmm, did I put my old SU-V4X in the loft, or chuck it in a skip? "
it will be the latter. On speakers that were right for them, they
sounded good.
I bought Mission 707 speakers at the same time as the amp
>got a ton of blown speakers in the garage.
The 707s died from rotten rubber gaskets, and got chucked before I found
you could buy refurb kits for them, still have the stands and original
cardboard boxes for them though!
<later>
Just ventured up into the loft and the amp (actually the SU-V2X) is
there in its original box, ebay says good examples sell for ÂŁ40-ÂŁ60, so
it can stay there.
Guest
On Monday, August 15, 2016 at 3:25:14 PM UTC-4, jurb...@gmail.com wrote:
> I have seen some really awful soldering. Some of these people should not be techs.
It used to be ham fisted techs, now it's the owner. Twice this year I had to salvage two projection TVs that the customers had tried to repair using a kit bought off line. One was a Mitsubishi xx511 series and the other that Sony with the conv amps on the HV/sweep board. Both were completely botched, the Sony missing a smd resistor. I quoted a price to repair/retrace the boards with no guarantee that the convergence parts they purchased were any good, and made them pay up front before powering them up.
Surprisingly, both worked after repairing the PC damage.
> I have seen some really awful soldering. Some of these people should not be techs.
It used to be ham fisted techs, now it's the owner. Twice this year I had to salvage two projection TVs that the customers had tried to repair using a kit bought off line. One was a Mitsubishi xx511 series and the other that Sony with the conv amps on the HV/sweep board. Both were completely botched, the Sony missing a smd resistor. I quoted a price to repair/retrace the boards with no guarantee that the convergence parts they purchased were any good, and made them pay up front before powering them up.
Surprisingly, both worked after repairing the PC damage.