I want to White Oak a Phase Linear 400 Series I

[Skratch]

Sutton, Sneak over to Kevins house and swap amps Problem solved

 

[mlucitt]

It's not perfect but if you can open PowerPoint, here are three slides that will help in the wiring of the DC Protect Board.

 

[ksrigg]

Hadn't thought of that one. I think he does work tomorrow. I would have time to change out the faceplates. That would be the big giveaway...The one I have isn't nearly as pretty as the one Kevin has..

And I don't have PowerPoint...so I'm still a bit confused. I know where connection 1 of the last bank goes....DC+ and number 3 goes to AC at the BR. The middle connection in the last bank on Don's board goes to STAR ground on Joe's board...but I'll need to figure out where that is on Joe's board, plus you DO NOT ground the inputs, as per Don's instructions.....this is my understanding so far...

 

[mlucitt]

OH, now I figured out your confusion. The STAR ground is not on Joes board. It is the copper bussbar between the bulk storage caps. Run the ground from Don's board to that point between the big caps, not Joe's board.

Mark

 

[laatsch55]

n I second that. FWIW.

 

[kevin]

Ok... doors locked tomorrow

 

[Skratch]

Men Just finished upgrading my virgin (Pam) 400 which I bought in the early 70's. All new .22 5% MO resistors, 1% 150 and 10 ohm on the output section, White oak driver board, LED board and PS caps, Dons protection board, 35 amp 800 volt BR, 15024 and 21196 outputs, 2n5088 bias transistors. When I fired it up I had a problem with the right channel bias, would not go above 170mv and Q7 got pretty hot. Got with Joe and he told me to check the TO-3 drivers in that channel. Pulled the drivers and cleaned the sockets with my 1/32 inch wire brush and reinstalled drivers. Biased up perfectly after that. Current draw was within 3%, bias at a steady .380 Output was at 47 volts before clipping on both channels. Sounded GREAT

 

[laatsch55]

Good job Mark. Impressive to do list. Did the 2N5088's come with heatsinks??

 

[Skratch]

Lee, The 2N5088 does not come with heatsinks, had to rob them from the 3403's. Joe sent them to me with my first WO board. They thermal track just as good or better than the 3403's and I used the wire from an old ethernet cable as leads, very flexible. Doing another complete rebuild for a guy with everything new except the VU meters

 

[Skratch]

Lee, Do you have any extra 1304 and 1305 trannies

 

[laatsch55]

Ok, thought so. I've been saving my gutshot 3403's for this day. The gain on the 03's has become so questionable. Could be I got some counterfeits too. Glad we have an alternative. Mark I also have in the neighborhood of 350-400 ----1304, 1305 pairs, let me know if you need some of those. I have about 20 reels of different bundled wires like that ethernet stuff, and so far the best for what we are doing comes from Lufkin Automation, the same Lufkin that builds pumping units. The signal cable is used to hook up their pump-off controller, very good stuff.

 

[Gepetto]

Hi Mark
Just to let you know, the 2N5088's I sent you were a matched pair so not sure if run of the mill 2N5088s will track as accurately as that set but should be close. The range of selected devices I have is not all that wide so you will probably be fine with random selection.

It is not that critical on the bias anyway.

 

[Gepetto]

Guys the other alternate I am looking at right now is the MPSA18 device. These are a better all around device than the TIS97 for the front end pair and better than the 2N3403's for the bias application.

Will advise on the results with these.

 

[laatsch55]

Phase used a lot of MPSA18 in the front. I've swapped out a bunch anyway. That would be nice to have one number replace 2.

 

[Gepetto]

And you can get the MPSA18 from On Semi which is the industry premier semiconductor company for discrete devices (now that Motorola sold off that business to them) instead of Fairchild (not bad but prefer On Semi)

 

[laatsch55]

Motorla did have their niche carved out.

 

[Skratch]

Lee, Don't need 1304 or 1305, The amp that I am going to rebuild were fine. Cleaning the heat transfer grease out of this one is going to take some time, some had greased sil-pads and some mica. There is grease everywhere. Bought another can of WD-40 and 2 cans of electronic cleaner for this one. How are you doing on your 1.3kw?

 

[laatsch55]

Wasn't happy with the toroids I had , They did not come with a VA rating, I don't suppose it's that hard to figurer out, BUT, some surplus toroids that were wound for some Mark Levinson gear came up on e-bay so I snatched em up. Dual primary 120 windings and dual secondary center tapped windings of 163 and 112. After seeing what the analyzer told me last night my PLWO SDDM might land in that area. I was waiting for Joe to politely suggest that perhaps my test procedures were off somehow as I'm still in the " don't hardly believe it" camp.

 

[laatsch55]

Mark, I wasn't too concerned about the grease, until I had a biasing problem also, that was traced back to a socket problem. the grease was contributing to it.

 

[Gepetto]

To remove the old dried up grease, I take a wooden paint stir stick and rubber band a paper towel around the end and soak it up with Isopropyl alchohol. It fits nice inside the heatsink channels and does a good job of removing the old grease and you can work it from the top of the amp for easy access. Requires a couple of paper towel changes to get it really clean but the method works well.