I want to White Oak a Phase Linear 400 Series I

[Gepetto]

Good move Mark, I use 26AWG, the original 20AWG is way too stiff, especially after aging in the amp for 40 years. Did you use the 2N5088's for the bias transistors?

 

[Skratch]

Used the 2n5088. The right channel with the original 2n3403 transistor would not bias above 300 mv, so I changed it and it biased correctly. Should the old bias transistors be changed out when you upgrade the amp with your board?

 

[ksrigg]

Here are pictures of the voltages at the storage caps...83.4 V and -83.4 volts. The meter was going back and forth on both sides by a tenth of a volt or so...so I think it looks like a transformer that is on the hot side.

Thanks Mark for helping me figure this one out. And also thanks for all the other tips. I will be playing with the amp for a few days now using the DBT and variac..

I also will listen to it with its' original PCB and output transistors. I will then proceed to changing out the PCB and adding the protect circuit. I am so happy.

It looks like I received a rare working Phase Linear....after replacing a broken fuse holder and cut ac cord and add a new BR..and caps..(which read really weird..)

I will not be useing any of my favorite speakers though until I can add the protect circuit and change the transisters...

I am so tickled.. Thank you Mark for your help. You are the man...And thank you Lord for providing an amp which I might be able to fix!!

 

[Gepetto]

Hi Mark
On your question, not necessary to always swap out the 2N3403s, many are still fine and can be reused

 

[laatsch55]

Does the 2N5088 come with the heatsink or do we need to rob one off a gutshot 3403??

 

[ksrigg]

What are you all using to cut the old thermal grease from the transistor seats? alcohol, kerosene, goo-gone....what works the best? I plan to replace the transistors, put Don's protection Circiut in place, solder the new PCB in, and then be DONE...and ready for testing...

Also, do you go back with the thermal compound on the chassis, then the mica insulator, and then more thermal coumpound, or would it be a neater and just as effective way to put the thermal compound in just one location, leaving the transistor clean, with it just up against the mica? Sorry to be so OCDC...but I'd rather do that than make DC or AC destroying my speakers or AMP!

 

[ksrigg]

ANd Joe,

On the led board...on the wiring pads, the first two wires change places, is that right? Mine are currently reversed from what you show in the instructions, red, white, black and then two khaki colored wires. Should be white, red, black and then the two other grey or khaki colored wires in no particular order. Is this correct?

Thanks

 

[ksrigg]

So......what was the previous owner up to with these diodes soldered on the back of the PCB? Anyone have any ideas? I just thought it might be of some interest to you guys. I never had posted a picture showing the entire back of the board.

Thanks for comments....

 

[Gepetto]

probably a hack job of replacing the original 1N4148 diodes in the bias circuit would be my guess based on their location. Suspect the guy had no 1N4148s available so he just used 1N4001s instead.

 

[Gepetto]

Hi Sutton
Yes, you have the correct order on the LED board wiring. From the bottom up, White, Red, Black and then either 2 grays, 2 khakis or 2 greens depending on the build vintage. The last 2 the order does not matter as these are the AC inputs to light the LEDs. The first 3 are the meter connections.

 

[ksrigg]

I just picked off another Phase Linear 400 Series I for my favorite price....$159.00...this time I did have to pay shipping, but still...........for $200.00 a nice example of this wonderful amplifier, and all I need is another Protection Circuit from Don.

Here she is:

http://www.ebay.com/itm/290664978708?ss ... 1497.l2649

This one, I am going to try to do a little better job. I will not use spade connectors for the BR..I will run three conductor power with and EIC connector. I will try to sort out and re-route all the wiring with AC..Just not get in such a big hurry to "git er dun"...

But, I don't know how much patience I have. This will be a test..

What BR is everyone using? 50 Amp? I was looking at them on Mouser, but there are several different choices...What do you all think?

905-KBPC5006T/W is one Mouser number..........

Last night I pulled 5 or 10 choices up, but today I can't find them. They said NEW at Mouser...but all had various voltage ratings and reverse voltage and other stuff that went right by me...

And is anyone concerned with Don's protect circuit? Do I need to wait for a revision, or are we all good with the circuit?

 

[mlucitt]

The Mouser P/N number you are looking for is 905-KBPC50010T/W

But don't order one now. I will put one in the package of terminal blocks (2 sets, enough for 2 amps) that is going out to you today.

Mark

 

[ksrigg]

Mark,

Thanks a bunch...I really appreciate that. And by the way....how do you tell the polarity of a transistor? I'm talking the driver and output transistor for the Phase Linear 400? Do they go in the amp so that they are "right side" up.....ie...readable, or do they go in "up side down" or readable only if the amp is upside down or if you are standing on your head?

Thanks so much Mark, Joe, Lee and everyone who is helping me get my "amp legs"
This is something I have always wanted to be able to do, and I am now getting my feet wet in the rebuilding of the Phase.

 

[mlucitt]

The beauty of the TO-3 transistor design is that the case determines the "polarity" and as you can tell by looking at the bottom of one, the leads are not in the center. No way to put them in backwards, just line up the holes for the screws.

Also, this is a good time to talk about buttering the drivers and outputs. Every builder has their own style and this is mine: I use the tab from one of my dress shirts, it has a round end and a pointy end and it is soft plastic. You don't want to scratch anything here. I squeeze some silicone heatsink compound on the tab and apply it to the base of the transistor but avoiding the leads, or you can use your fingers (just wash your hands well afterwards). I try to move from the middle outwards. The ideal film is one you can almost see through, but not quite. It does not take very much and any that squeezes out does you exactly no good at all.
Then I lay a 'clean' mica on top of the freshly buttered transistor and coat the mica the same way - starting from the middle and working to the edges, avoiding the leads. Then I install the transistor by using a set of small slip-joint pliers to hold the case while I drop it into position. Add the two screws and torque to 6 inch-pounds (4-7 is the range, see below) and this is not tight at all; when the screw stops and then about 1/8th of a turn more. Then I measure to ensure there is no conductivity (infinite ohms) between any part of the transistor case or leads and the heatsink.

Good luck and take your time.

torque reference: http://www.ti.com/lit/an/sboa020/sboa020.pdf" onclick="window.open(this.href);return false;

 

[ksrigg]

I'm running into a stumbleing block. Here is a picture of the Protect Circuit. What else do I need to do? Using Joe's PCB as Iunderstand it, dictates changes to the AC, DC and Ground connections. Can anyone tell me what else I ned to do? Do I run from the small copper pad near in inputs to the big copper buss on the caps, Where do I pick up the AC on the BR and where do I get the DC the Protect Circuit needs? Or do I need all these connections?

 

[ksrigg]

So so I pick up AC from one of the two white wire that go to the BR, and the other DC and Ground as in the picture linked below? Will that work? Or do I need to change it, using the White Oak Board?

http://www.flickr.com/photos/watts_abun ... otostream/

 

[Skratch]

Sutton, When I change outputs, I have a 1/32 inch stainless steel brush that I run through the TO-3 Base and Emitter holes to remove anything in them, Oxidation and Heat sink compound. I had a problem with an amp after I changed outputs that would not bias up properly and the problem was a little oxidation on the driver transistor pin socket. Joe helped me get this solved

 

[ksrigg]

Thanks Skratch...I'm just trying to figure out where the last four wires go in a wattsabundant Circuit Protect circuit. I think I know, but am not sure, as Mark told me not to run the ground from the input buss to the cap buss. The other ones, I think I can see from Don's Flikr pics, but I just want to make sure. I still have to put these four wires in, and then replace the driver board (White Oak) and then I will be ready for testing. If someone will help me figure this out. I thank you, and think I have it. I just want to make sure, and I'm sure Kevin doesn't want me to take his PLWO400 apart to look.

 

[Skratch]

Sutton, There is only 3 wires, Red is +80volt , White is ground which can be run like the picture or back to the ground bar. Purple or black wire, what ever color you use goes to one of the AC termonals on the Bridge rectifier. I think the other white wire your talking about is for the input grounds that should be run from the ground bar to the input. I also run a white ground from the ground bar to the white oak board ground

 

[kevin]

O no.... My house is not locked...