MJ21196G buy anybody?
- Thread starter WOPL Sniffer
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- Born and Raised In The 700 Watt Club.
You know....I’ve Heard of the PL909’s and the MJ21996’s; but I’ve Never heard of 2SD555’s? And that’s exactly what one of my amps has in it for the right channel. The left had the 909’s. Oddly enough; thats the only channel I hardly get any power out of; and the only one that the meters barely budge when cranked. I’m thinking those are NOT supposed to be there and someone blew that channel and replaced the transistors with these? Shouldn’t the ideal part BE the MJ21996’s? I may need to get some......
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- Born and Raised In The 700 Watt Club.
x8 amps Perry @$2500 a piece to WO. I’ll fix the time bomb when I win the lottery. You don’t have to remind me. Joe; It was the only one out of the 8 that used these so I presummed it was the reason for the channel having very low output. I am a Phanatic of the amps yes, but not so much that I understand every nut and bolt from the inside out. I think I’ve made that pretty clear in my forum discussions since 2013. I have yet to actually pull one apart and start a whiteoaking from the ground up.
Like Fred said; getting the core amps is the first part. Before you can’t find them anymore. Restoring them one at a time is a great retirement project. At 70hrs a week at my day job; it’s not happenin anytime soon. Till then, I will still love my amps for what they are. Time bombs or not. Still have my love for them. Most beautiful amps ever made even by todays standards IMHO.
Joe, Your new LED boards are a start; and one of the easiest and most painless things you can do to these to really make them look alive. Better to start with One WO board than none at all right? Haha. Baby steps. I may decide to make the amp that has those Transistors in there the one that I do a Full WO on. Since it’s the lame duck of the group.
Like Fred said; getting the core amps is the first part. Before you can’t find them anymore. Restoring them one at a time is a great retirement project. At 70hrs a week at my day job; it’s not happenin anytime soon. Till then, I will still love my amps for what they are. Time bombs or not. Still have my love for them. Most beautiful amps ever made even by todays standards IMHO.
Joe, Your new LED boards are a start; and one of the easiest and most painless things you can do to these to really make them look alive. Better to start with One WO board than none at all right? Haha. Baby steps. I may decide to make the amp that has those Transistors in there the one that I do a Full WO on. Since it’s the lame duck of the group.
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- Born and Raised In The 700 Watt Club.
That being true Joe, I wouldn't want them to stay in there. If out of 8 Amplifiers, this is the only one that has them in there and it IS in the channel that exhibits weakness or low output; then the question was to be understood as not questioning the legitimacy of their usage; but directing thoughts as to them being the reason for the weak output in the amps channel and if they were widely used or not. THAT was where the question stood. I get that just because I haven't seen em used doesn't mean they aren't legit. But Are they the main culprit? I thought I'd get someone saying "Yeah PL advised using those as replacements but they are junk. And we recommend using THESE instead. So they should have used x,y,z part". After all I have seen SO many posts on this forum over the years about how consistency was NOT key at PL. So out of 160 transistors, I have 10 that are the 2SD555's; naturally I asked the question since this is the only channel that has failure.
If they definitely are the worst they ever made; then ehhhhh, time for another consideration. Also; I have the original service manual, and I just checked (thanks) and that bulletin is in there. But I have no intention of servicing the amp with replacement parts of the same "junk" as it's been notified to me here. I would scrap fixing it entirely and decide to White Oak the whole thing. My intent is to eventually get a WO overhaul with the weakest of my bunch. I mean who wouldn't want that?! At least that'd leave me with only 7 ticking time bombs....... IF I can bring myself to give me an early Christmas gift? But I ain't retired yet and don't have the time to do the work. And probably not the patience. Even though Jerry and Lee think I do. I mean at least by the time I AM retired, Joe will have the Rev K boards out!
Joe always makin things better.
If they definitely are the worst they ever made; then ehhhhh, time for another consideration. Also; I have the original service manual, and I just checked (thanks) and that bulletin is in there. But I have no intention of servicing the amp with replacement parts of the same "junk" as it's been notified to me here. I would scrap fixing it entirely and decide to White Oak the whole thing. My intent is to eventually get a WO overhaul with the weakest of my bunch. I mean who wouldn't want that?! At least that'd leave me with only 7 ticking time bombs....... IF I can bring myself to give me an early Christmas gift? But I ain't retired yet and don't have the time to do the work. And probably not the patience. Even though Jerry and Lee think I do. I mean at least by the time I AM retired, Joe will have the Rev K boards out!
Joe always makin things better.
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- St. Louis, MO.
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- Born and Raised In The 700 Watt Club.
Fantastic. Thanks for the helpful advice. In your own opinion; would you change these out? Or would you spend the time to otherwise WO it? I’m guessing most of the main members here have done it to their own amps. And if they didn’t; what builder did they use? I have seen many others here.
My father wants to have his 400 done up. I said a 700B would be a better idea but he says its overkill for him. He says the 400s always sounded “warmer” anyway. I think that excuse is negated when you WO an amp. -I believe I have another thread here somewhere where I talk of this. I need to revive it because he is retiring in two months. He’s made it clear his main focus will the the stereo system. So I’ll need to pick the brains of you smart gents as I always have.
My father wants to have his 400 done up. I said a 700B would be a better idea but he says its overkill for him. He says the 400s always sounded “warmer” anyway. I think that excuse is negated when you WO an amp. -I believe I have another thread here somewhere where I talk of this. I need to revive it because he is retiring in two months. He’s made it clear his main focus will the the stereo system. So I’ll need to pick the brains of you smart gents as I always have.
Working to upgrade these amplifiers is a slippery slope. You upgrade the ten output transistors to keep them from failing, but think, hey - I'll just replace them all so the amp can 'breathe' a little better and you find out that the best way to exploit the new capability of your higher gain outputs is to install a new WOA Control board. Then you find yourself in WIIT (while I'm in there...) mode, so you upgrade the bulk capacitors and the ancient bridge rectifier. Then you decide, hey I'm already 90% there, so let's install the Backplane Boards. And now you have a WOPL, as Perry would say.
I would change out the 2SD555 devices, but not because they are ticking time bombs. Who cares, you only need the transformer and the heat sinks; everything else is available to you. I would change them because the ON Semi MJ21195G/MJ21196G output transistors are just so much better. Then you can also get rid of the mica and grease, and install the Bergquist Sil-Pads that make changing the transistors so much easier.
I would change out the 2SD555 devices, but not because they are ticking time bombs. Who cares, you only need the transformer and the heat sinks; everything else is available to you. I would change them because the ON Semi MJ21195G/MJ21196G output transistors are just so much better. Then you can also get rid of the mica and grease, and install the Bergquist Sil-Pads that make changing the transistors so much easier.