David's Phase Linear 700B Thread

jbeckva

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Uh oooooh....

The WO board got "whomped" a little folks. One casualty was Q8 of which we're going to have to go to Lee or Joe for those 2N1304's.

Here's what I have offlining it.. Hopefully that's it.

Q10 open all the way around
Q8 open all the way around
D9 short


Joe is Q8/9 matched? Looks like we'll need a set from you. Send me an invoice eh? :toothy10:
 
Phase Linear Phanatic

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jbeckva said:
The WO board got "whomped" a little folks. One casualty was Q8 of which we're going to have to go to Lee or Joe for those 2N1304's.

Here's what I have offlining it.. Hopefully that's it.

Q10 open all the way around
Q8 open all the way around
D9 short


Joe is Q8/9 matched? Looks like we'll need a set from you. Send me an invoice eh? :toothy10:
Click to expand...
What the????? What could have happened to cause such mass casualties? ONE little solder blob accross the transistor rail and all that? I just paid near two Benjamin's for that board? I'm flabergasted, and dismayed at the same time? Invoice? Oh noooo.........:sad2:
 
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Phase Linear Phanatic said:
What the????? What could have happened to cause such mass casualties? ONE little solder blob accross the transistor rail and all that? I just paid near two Benjamin's for that board? I'm flabergasted, and dismayed at the same time? Invoice? Oh noooo.........:sad2:
Click to expand...
Well looking back here on page 1 or 2... the "blob" at least on one end was on the whole 80 volt positive rail with 8 amps max, the other?.. hmmm.. where was that blob exactly, heheh?? Ya did say you did the "zap", twice. :confused3::confused3: Like I said - that's why I cut those diodes thinking it .. just.. HAD to be them, because if not then that would shift the focus square on the outputs.:cyclopsani:

Yeah, definitely took quite a bit out, but other than the stuff on the WO board it all was coming out anyway. The outputs going in are "hefty HEFTY HEFTY" compared to the RCA 1B05's that were taken out. What broke on the WO board isn't much except Q8.

AND IN FACT...

I still have that old factory board out of the 400 I just did, complete with TWO sets of 1304/1305's. So.. if they check out I just might cannibalize from that instead. I believe somewhere too I have the 2N3439's needed for Q10, so you're in luck there.

Work's progressin'... I need to order some diodes (the lazy method) or I can run to the "shack" tomorrow for them and a few other odds n ends.
 
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Phase Linear Phanatic said:
What the????? What could have happened to cause such mass casualties? ONE little solder blob accross the transistor rail and all that? I just paid near two Benjamin's for that board? I'm flabergasted, and dismayed at the same time? Invoice? Oh noooo.........:sad2:
Click to expand...

If it was easy, everyone would be doing it...............................
 
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Jerr, is there anything you can rob from the old 700b driver board I gave ya? Or does that not enter into Joes board? Yeah.....I discussed with Lee about those transistors being tired. If they hadn't been blown, I would have had them replaced anyway. I am glad you are replacing the diodes. I guess its good to have all new internals. That "blob" I believe was laying across the left channel rail. Last transistor at the bottom. Near the transformer. Probably caused a cascade effect when I powered that thing on. Explains why It blackened 8 Amp fuses to a crisp instantly. Twice.
 
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laatsch55

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One of the first things mentioned in the 700B manual----" If a fuse looks as though it has been vaporized,DO NOT REPLACE AND POWER UP AGAIN, find the problem, then bring it up using a variac and current limiter"....


Their caps not mine....
 
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laatsch55 said:
One of the first things mentioned in the 700B manual----" If a fuse looks as though it has been vaporized,DO NOT REPLACE AND POWER UP AGAIN, find the problem, then bring it up using a variac and current limiter"....


Their caps not mine....
Click to expand...
There was more than ONE solder blob Lee. I removed what I believed was the infraction. The aforementioned "blob". I mentioned the meter swing the first time the fuses blew and upon suggestion from this forum, I tried a second time after fixing what I believed to be the cause of the problem to see If I got the same result. Look back. (You will see it was suggested). Possibly in the old Bulk capacitor replacement procedure thread. I am an enthusiast. Not a hobbyist and do not own test bench equipment such as variacs and oscilloscopes. Hell I don't even possess a decent DMM at this location. it works out anyway. Since I am having all the guts replaced. What could go wrong? Right Jerr? ;-)

Lee, you must have a different manual than me. Mine says SHOULD THE AMPLIFIER MALFUNCTION IN ANY MANNER, REPLACE ITS FUSES. 99% of all problems with the phase linear 700B can be resolved by replacing fuses. THEIR words. Not Mine. So can you blame me for replacing them and trying again? Trust me. I referred to the forum and my manual before I proceeded. :-/
 
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Phase Linear Phanatic said:
There was more than ONE solder blob Lee. I removed what I believed was the infraction. The aforementioned "blob". I mentioned the meter swing the first time the fuses blew and upon suggestion from this forum, I tried a second time after fixing what I believed to be the cause of the problem to see If I got the same result. Look back. (You will see it was suggested). Possibly in the old Bulk capacitor replacement procedure thread. I am an enthusiast. Not a hobbyist and do not own test bench equipment such as variacs and oscilloscopes. Hell I don't even possess a decent DMM at this location. it works out anyway. Since I am having all the guts replaced. What could go wrong? Right Jerr? ;-)

Lee, you must have a different manual than me. Mine says SHOULD THE AMPLIFIER MALFUNCTION IN ANY MANNER, REPLACE ITS FUSES. 99% of all problems with the phase linear 700B can be resolved by replacing fuses. THEIR words. Not Mine. So can you blame me for replacing them and trying again? Trust me. I referred to the forum and my manual before I proceeded. :-/
Click to expand...
Yep, should be fine Bud... The MJ's we should make mandatory as they are replacing old rebranded trannies not really optimized for audio - especially if observed that just a few were replaced. That is IMHO of course, but I also go by experience back in the Nav days. We had these circuit cards in our test bench that had a DAC controlling a +/-30 volt mini power supply (was 160 of them in the test bench in total). Whenever we had one fault out, no questions asked, we replaced every single output transistor. Had a new guy try to say we shotgunned it, and he only replaced the one that shorted out. Stuck it back in the bench, powered up, and tons of smoke blew out of the back of the bench. We made HIM do the full board repair (the 3 inch hole the "thermal event" burned in the board) - took a couple of days.... :cyclopsani:

Moral of the story - why risk your speakers on 30 year old devices, when there are better ones out there that will give it another 30 years of good service.
 
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jbeckva said:
Yep, should be fine Bud... The MJ's we should make mandatory as they are replacing old rebranded trannies not really optimized for audio - especially if observed that just a few were replaced. That is IMHO of course, but I also go by experience back in the Nav days. We had these circuit cards in our test bench that had a DAC controlling a +/-30 volt mini power supply (was 160 of them in the test bench in total). Whenever we had one fault out, no questions asked, we replaced every single output transistor. Had a new guy try to say we shotgunned it, and he only replaced the one that shorted out. Stuck it back in the bench, powered up, and tons of smoke blew out of the back of the bench. We made HIM do the full board repair (the 3 inch hole the "thermal event" burned in the board) - took a couple of days.... :cyclopsani:

Moral of the story - why risk your speakers on 30 year old devices, when there are better ones out there that will give it another 30 years of good service.
Click to expand...
Agreed there Jerr. More or less though, it's my O.C.D. kicking in there with the whole "if one bulb is out, replace the whole strand" theory. For analogy, this guy at work has been complaining of the tires on his car. Each month or so, he gets a new flat in one of the tread worn tires. To save $$ he replaces them one by one. But then each tire has a different lifespan and even brand if they are out of stock on what they had last month? My choice is just bite the bullet and get all the same upgraded tire at once. That's my methodology to my amp. All new resistors, diodes, transistors....etc. if it ain't broke; don't fix it?? Is that what they say? Well I say, then you'll be fixin it again and again and again as each 30yr old part fails. Overhaul man! That's the best you can get! :thumbright:

Speaking of "thermal event", did you notice the one TO3 socket on the right channel that looks charred? Is that something we should address?
 
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Phase Linear Phanatic said:
Agreed there Jerr. More or less though, it's my O.C.D. kicking in there with the whole "if one bulb is out, replace the whole strand" theory. For analogy, this guy at work has been complaining of the tires on his car. Each month or so, he gets a new flat in one of the tread worn tires. To save $$ he replaces them one by one. But then each tire has a different lifespan and even brand if they are out of stock on what they had last month? My choice is just bite the bullet and get all the same upgraded tire at once. That's my methodology to my amp. All new resistors, diodes, transistors....etc. if it ain't broke; don't fix it?? Is that what they say? Well I say, then you'll be fixin it again and again and again as each 30yr old part fails. Overhaul man! That's the best you can get! :thumbright:

Speaking of "thermal event", did you notice the one TO3 socket on the right channel that looks charred? Is that something we should address?
Click to expand...
I've cleaned it up a little and excavated to see how deep - superficial from what I see so far. When I get to the point of filling in the bank (probably tomorrow) I'll take a real good look and replace it if needed. No sweat.. I have a few sockets already.
 
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jbeckva said:
I've cleaned it up a little and excavated to see how deep - superficial from what I see so far. When I get to the point of filling in the bank (probably tomorrow) I'll take a real good look and replace it if needed. No sweat.. I have a few sockets already.
Click to expand...
SWEET!! Well I'm headed to dreamland for the evening. Just finished a 70hr work week. I feel like a zombie right now. I know I shouldn't bitch, cause Lee's got me beat there. But for a guy that's supposed to be only doing 40hrs..... I suppose they are testing me. :tongue10:
 
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Dave, I remember telling you you to replace and try again. there are two types of fuse burn events, a slow heat and burn of a rail being over driven, and an explosive type from a dead short. The first is a common occurance, the second not as much.
 
Phase Linear Phanatic

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There is a pretty nice crop of Phase Linear gear on ebay right now. Including some 700B's. :cyclopsani: Hmmmmm......think maybe I should add to my stack and have an all 700B's Avatar? He hee.....:toothy10:
 
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Hey; I JUST noticed this, but how is it my thread has a 5-star rating? I don't even remember putting a vote out for that myself? It's the only topic in this thread I see with one? Kudos to whoever did that tho?
 
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