Vintage HiFi Audio Forum
Audio Discussion => DIY => Topic started by: OldiesButGoodies on September 11, 2016, 11:57:19 AM
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Woke up this morning, went to my shop to work on a CD player that is not responding to the skip button. Turned on NPR radio on the Toshiba tuner going through the Phase Linear 2000/400 combo and got to work. At one point I moved the PL400 a bit to get to the back of the pre and connect the CD and *poof* smoke billowed from the right Genesis speaker! Luckily the left one was disconnected as I had a small cheap sony tester speaker hooked up. Both the Sony and the one Genesis are toast (well, I can sell the recently re-foamed passive radiator from the Genesis for parts I guess). The cause: 80V of pure DC power to both channels. One of the two 2N1304 bias transistors came disconnected from the driver board and caused a cascade of damage that included 4 PL909 output transistors spread across both channels. Luckily the Oak Audio driver board did not suffer any damage (that thing is a battle tank - recommended upgrade!), and after replacing the 1304 and the 4 PL909s, the Flame Linear 400 is biased and singing again (that speaker destroying SOB). Before I hook any more speakers in a permanent fashion, I will wire up this speaker protection relay that I ignored installing for so long...
The flame linear reputation lives on!
(https://c3.staticflickr.com/9/8875/29316634890_d6874c3902_b.jpg) (https://flic.kr/p/LEBqbf)Oouch (https://flic.kr/p/LEBqbf) by Jose Sifontes (https://www.flickr.com/photos/jsifontes/), on Flickr
(https://c8.staticflickr.com/9/8309/29528193191_28ace56257_b.jpg) (https://flic.kr/p/LZiH6a)Untitled (https://flic.kr/p/LZiH6a) by Jose Sifontes (https://www.flickr.com/photos/jsifontes/), on Flickr
When the Phase Linear works it sounds REALLY good. When it goes nuts, it goes really nuts. Respect those two bias transistors!
OBG
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Is that amp that great as to risk damage to other equipment, or possibly cause a fire?
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80V. That'll do it. That relay is like the tooth that is cracked but you don't go to the dentist until it actually starts hurting.
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Well
George Geoff, on behalf of my recently diceased Genesis 20 speaker, I would have to say no.... (anyone Have a pair of Genesis and is looking for a center channel? or maybe a pair of Genesis 10s that would want to upgrade to the version with passive radiators? :P I digresss...).
IMO the 70V (or 80V in my case) failure mode is rare - it happened to me because I flipped that driver board down so many times that the leads to Q6 were understandably ready to come disconnected [Edit: and the nuts that attach it to the chassis were loose - that did not help either]. Not everyone will have that problem. And if you add the relay protection you should be fine (which Scott [BMW75] did early on in his PL700, I ignored his advice, my bad).
So I will just fix the original design flaw by adding the safety circuit and continue using it in the shop.
OBG
PS - No plans to connect it to my B&W 803s any time in the near future... the above notwithstanding :(|)
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You're taking this much better than I would have. A had on old power amp to the same to a pair of KLH Model 6 speakers. I avoid old power amps now. Just gun shy I guess. But on a happier note im glad you were able to fix the PL400.
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Life would be boring without the occasional need for a fire extinguisher. These things are fixable. Progressive diseases without a cure that kill humans, those piss me off, cannot fix those.
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I've got a pair of Genesis, I believe g2 I can't keep it all straight anymore, hooked up to the girls tv. I refoamed them after hearing your Genesis awhile back and they sound good hooked up to a newer Marantz black face ht amp. That's a shame you cooked one, I thought they sounded great. Not sure your good Genesis will fit where the current junk center is, but if the price is right I might try it out.
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Life would be boring without the occasional need for a fire extinguisher.
Truer words were never spoken.
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My PL 700B had 80V on the speaker outputs the day I brought it home.
Installed the White Oak control board and Imlay speaker protect relay before ever connecting it to speaker. Guess I'm a two rubber guy.
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Guess I'm a two rubber guy.
lmao - yes you are, good for you!
A generous member of the forum has offered a spare epi woofer to resuscitate the Genesis (the tweeter somehow survived the 80Vs), so I guess I will be in business again soon.
This time I will put the relay in line before turing connecting the speakers, be more like Scott!
OBG
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Life would be boring without the occasional need for a fire extinguisher. These things are fixable. Progressive diseases without a cure that kill humans, those piss me off, cannot fix those.
I definitely have to agree with above statement! Chemo Tuesday in two days. Shit
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Good Luck PBJ
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Good Luck PBJ
Thanks MG
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Pepe,
Glad to hear you will be able to restore the Genesis speakers!!! :)
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Pepe,
My PL 700B welded the power relay closed in the Monster power unit it is plugged into. The plug in is supposed to have a delayed start and turn the amp on after everything else powers up. Was rocking it pretty hard one day and the relay has never opened back up again. Instant on power on that Monster circuit now.
Regards,
Scott
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Would adding an appropriate size cap in the power supply help this surge issue on start? are the speakers popping on start?
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No speaker pop on start up. I think the White Oak board takes care of that problem.
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Would adding an appropriate size cap in the power supply help this surge issue on start? are the speakers popping on start?
I have just the opposite problem...pop on shutdown?
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Ok Scott. That audio board from Oak is great. Expensive but worth it.
King - can u confirm if the pop on shut down happens even if the pre is disconnected from the amp?
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All Flame Linear pop on shutdown unless they've been modified with the White Oak board or something similar. Mine popped very loudly on shutdown. They're known for that.