I want to White Oak a Phase Linear 400 Series I

[ksrigg]

I just removed the driver and output transistors from the second PL 400 I have been working on. I NOW HATE THERMAL COMPOUND. IT IS OFFICIAL. This amp had the stuff almost dripping off the leads on the transisors. I'll bet the reason I was getting funky readings on one of the "banks" of transistors is that there was so much compound one of the leads wasn't making contact. What a mess.

Now I have the majority of it cleaned up, but I'm going to have to run a toothpick or something through every lead terminal or something.. I just want to make sure all the gunk is out of there. I could spray WD-40 through each hole using the little straw....what is the best way to clean this stuff out of those little holes?

Plus, this guy used wonderful hex head screws for the transistors with NO SLOT or PHILLIPS threading... FUN!!

 

[laatsch55]

Ok, you got some funny readings when?? When you posted the pics?? You tested bias and offset, did you check for shorted outputs before you pulled em?? Do you know how to check the outputs once they are out??

 

[laatsch55]

I wouldn't be putting any "pick" type object through the output sockets. they are pretty old and ----spread---- anyway. AND IF you do, go back and squeeze the pressure tabs back together for a better bite.

 

[ksrigg]

Here is a picture you requested Lee. Discharge!!

I am stepping back and taking a breather right now. I do have some problems, and Mark is trying to help me through them. I may have to send this one off to him to fix too. It's just way harder than it looks. ()plus I'm probably making it a lot harder than it is..)I really wanted to do this, but the fact that there are only a handful of people capable of actually doing this, and only two people in the USA refered to by Joe as THE GO TO GUYS, then this is not something I am used to, and have NO training in. I have been sucessful in DIY speaker building, but this is a whole new ballgame, and it will take time to become proficient in.

I am trying though, and I think that is worth a little "atta boy"....but Mark can tell you more about my last attempt. I wasn't way off. I just had some grounding issues, but I was trying to follow directions which weren't exactly right for the combination of boards and things I was using..

I am trying...and I will get it....although eventually...

 

[mlucitt]

Yeah, the Wattsabundant board Don put together is good but the instructions assume the amp is original. When you correct the grounding in the amp to correlate with Joe's improved wiring the instructions can be confusing or in the worst case, contradictory. Don could not have seen these improvements coming, but we have learned that it takes someone familiar with electronics to sort out the anomalies and differences when they are present in certain amps.

 

[laatsch55]

Ok Sutton, I didn't know you and Mark were handling it. With no postings I was getting concerned.

 

[ksrigg]

If not a toothpick or something similar, how can you ever get the gunk out of the sockets? Maybe I shoudn't worry about it, an just squeeze the sockets a litle and let the transistor lead mechanically clean the socket tip enough to make good contact.

You didn't comment on the discharge resistor Lee. I made it over the top just for you...I may even mount it to a little piece of wood and really dress it up..

 

[Gepetto]

I never worry about the heat sink compound in the sockets Sutton. It won't affect the connection on a good socket. On a bad socket, being free of heatsink compound won't help it to become a good socket.

 

[mlucitt]

I wouldn't say we are handling it. More like Mark has no hair left and Sutton has learned how to re-wire a Bridge Rectifier (twice). Now we move on to more easily blown up components. I am tring to help Sutton keep the smoke on the inside of his parts, letting the smoke out will cause more gnashing of teeth and words that Sailors use.

 

[laatsch55]

If not a toothpick or something similar, how can you ever get the gunk out of the sockets? Maybe I shoudn't worry about it, an just squeeze the sockets a litle and let the transistor lead mechanically clean the socket tip enough to make good contact.

You didn't comment on the discharge resistor Lee. I made it over the top just for you...I may even mount it to a little piece of wood and really dress it up..

And in that I was remiss Sutton as I remember making such a case out of it. Excellent choice for a CAPACITOR DISCHARGING RESISTOR!!!

PS-BTW 50 watts is juuuuuuust right.

 

[ksrigg]

So I am assuming that the thermal compound conducts electricity? Or does just not enough of it get in the way typically to cause any problems? If I remember correctly, I thought Skratch had connection problems because of thermal compound? Did I misread a post?

 

[Gepetto]

It is non conductive. A good socket will wipe the film away and form a gas tight seal

 

[Skratch]

Sutton I had a problem with a driver not making contact, I cleaned the socket out with spray electronics cleaner and squeezed the pin socket and reinstalled the driver and the problem went away. I did not know that grease in the socket didn't matter but the last amp I did a rebuild on was so full of grease that when I pulled the drivers and outputs you could not see the transistor pins there was so much grease on them.

 

[ksrigg]

That is the same problem I have. These pins are all white, with the grease about as long as the pin when I pull them out. I don't think I could ever get it all out. Looks like the guy used an entire bottle or tube of thermal compound on these...It's just a mess. Makes me want to consider using silpads on anything I do....if I didn't already have the compound and mica...

What are the downsides to using silpads? Just the thermal transfer is much higher with the compound I would guess?

 

[laatsch55]

Sil-pads tear pretty easy. They are not the preferred method. There's a reason folks put up with the mess.

 

[Gepetto]

Hi Sutton
If you decide to use the mica with white thermal compound, go very sparingly. Most people think that "the bigger the blob, the better the job." Well that saying applies in some cases, but not in this one (this saying does not apply when soldering either).

The mica and white thermal compound make a junction with lower thermal resistance than the silpads.

 

[ksrigg]

Thanks...Mark gave me a B+ on the work done on the 400 I did. I tried to go very sparingly with the thermal compound, but think I still used a little too much. On this next one I am going to use even less. I now see that a little goes a very long way. I think the concept of the silpad is a good one...someone should make an improved version at some point with high thermal transfer qualities, and less mess. With all the technology, you would think someone would have alkready come with a space age thermo-plastic or even ceramic type compound which would retain its shape and still provide the thermal transfer...but it might be an economic issue more than anything else...

 

[laatsch55]

I don't think pandering to a dinosaur like a TO-3 is a viable business model nowadays.

 

[Gepetto]

Yeah you are right Lee, those TO-3s were too rugged, too high quality and most of all too expensive to produce for today's disposable electronics market

 

[laatsch55]

Yeah----what you said