My PL400 Series 1 Rebuild

[jle]

I started a new thread as I had threatened to do, as my 1st set of postings were all about planning, research, pretending that I tidied up the workbench, and getting necessary materials together. I have an early (but not the earliest) PL400 Series 4 4-fin. I secured 8-fin heat sinks with transistor covers, the updated transformer, a new chassis, Watts Abundant's DC protection board, and all the White Oak upgrade kits.

But where do I start?! The question is related mainly to the fact that I have not found a thread where someone does a rebuild that involves a new chassis. My sense is that the general approach removes the control board, upgrades the backplane, upgrade the control board, etc. But I need to start one step earlier (with the chassis). So, here is what I think I need to do:

• Install the transformer and heat-sink fins onto the new chassis. The need to add the other chassis hardware will become apparent as I go along (top and bottom, for example). I am assuming that the new chassis then forms the foundation for the rest of the rebuild, and gets built up with the other boards, big transistors, etc.
• If that assumption is correct, then the next thing to go in would be the backplane boards and the gradual installation and power-up procedures for the transistors.
• Don's instructions for the Watts Abundant board say that it gets installed first. But a comment from Don that was quoted in Nelson's thread said it goes after the backplane. So I am putting it here in the sequence.
• Next would be the control board
• Finally the light board

Does all that sound correct? I'll enjoy spending some relaxing time slowly and carefully building the backplane and control boards while the above plan gets corrected, tweaked and revised.

-Jon

 

[George S.]

Check the PDF files that Joe sent you. Joe also has a multimedia presentation on the build sequence. Maybe it's in the files.
Also look at Eric's "Hexis22" build threads. Lots of excellent photos. Look closely at how he positions the components on the boards in regards to component orientation, soldering, and wire routing.
Wire routing and dressing is critical for reliability and low noise.
Think I read every post on the forum before I built my first 400. I actually built two at the same time.
I did document my PL700Pro build here. Photos are no where as good as Eric's, but I do address some of the issues with reusing the old chassis, and they are in build sequence.
https://forums.phxaudiotape.com/threads/pl-700-pro-build.9965/

 

[jle]

Check the PDF files that Joe sent you. Joe also has a multimedia presentation on the build sequence. Maybe it's in the files. Also look at Eric's "Hexis22" build threads...
https://forums.phxaudiotape.com/threads/pl-700-pro-build.9965/

Thanks for the thoughts, George. I did those things before posting, but didn't find anything (yet) that started with a new chassis. Eric's build is humbling, or should I say "aspirational" -- I aspire to be that good with the wiring, dressing, etc. I'll keep reading (I know I have not found every build thread yet).

It just feels a little different than what I have read so far when throwing a new chassis into the mix. A "normal" rebuild would be a tear-down followed by building it back up. But I'm thinking instead that maybe I am starting with the chassis as a clean slate and building things up from there.

And of course, all of these paths remind me of "stone soup." That's were you take a clean stone, place it in a large pot with water, veggies, proteins, and seasonings. You let that simmer for a while, discard the stone and eat the soup. My original PL400 Series 1 is the stone.

-Jon

 

[George S.]

Oh, rule #1. Do not rush the build!
Hope you have the proper tools and work space.
Take your time and double and triple check everything.
You want it to power up with no issues.
Any questions, please ask, the community will help you!

 

[Gepetto]

Hi Jon
I sent you, amongst the many, many files one called Complete Rebuild Slide Show.docx. Look for that

PL400 Assembly Process Slide Show (Adobe Acrobat)

PL400 Assembly Process Slide Show (PowerPoint)

 

[WOPL Sniffer]

Save your back and hold off on the transformer install and sink install till you get the backplane boards in.

 

[jle]

Hi Jon
I sent you, amongst the many, many files one called Complete Rebuild Slide Show.docx. Look for that

(Jon smacks is palm against his forehead...) Joe, I had looked at that file, but in retrospect I was so focused on the boards, wires, etc., that I totally missed the fact that the slideshow is a precise answer to my very question. And it confirms my view of building on that foundation. I need to add "install big f'ing capacitors" to the project plan list.

 

[WOPL Sniffer]

MEN, FOLLOWING DIRECTIONS??? what's this world coming to?

 

[Hexis22]

Save your back and hold off on the transformer install and sink install till you get the backplane boards in.

Agree, complete the backplane board and control board assembly, then progress to chassis assembly. Transformer gets installed after securing the backplane boards and heat sinks.

Most of my build threads follow this sequence for a new chassis build. I’ve only built one amp with the original chassis, my first amp build, and ALL others with a new chassis.

 

[WOPL Sniffer]

Agree, complete the backplane board and control board assembly, then progress to chassis assembly. Transformer gets installed after securing the backplane boards and heat sinks.

Most of my build threads follow this sequence for a new chassis build. I’ve only built one amp with the original chassis, my first amp build, and ALL others with a new chassis.

Gotta have the White Oak chassis. More room and they are kick ass. Yeah, it's not often I use an original chassis. Matter of fact, I'm going to carry the old Pro 700 (a series II ) chassis and heat sinks next door and put them in Paul's metal recycle pile.

 

[mr_rye89]

Old heat sinks you say? Can you cut 700 heatsinks to fit a 400?

 

[WOPL Sniffer]

Old heat sinks you say? Can you cut 700 heatsinks to fit a 400?

Nope

 

[WOPL Sniffer]

Old heat sinks you say? Can you cut 700 heatsinks to fit a 400?

Kyle, why don't you find a 400 8 fin and use whatever parts you upgraded on IT? Or, somebody has to have a set here.

 

[jle]

I have started on the back plane boards. I overlooked the suggestion from Marc's excellent videos about mounting the 0.33 Ohm 3W resistors raised up a bit from the boards, and instead mounted them flush to the boards as shown in the WO Assembly Notes.

How critical is that raised installation (for heat dissipation I assume)? Is it worth it to desolder the flush-mounted ones and replace them with a set mounted with Marc's tongue-depressor elevated mounting trick?

 

[Gepetto]

I have started on the back plane boards. I overlooked the suggestion from Marc's excellent videos about mounting the 0.33 Ohm 3W resistors raised up a bit from the boards, and instead mounted them flush to the boards as shown in the WO Assembly Notes.

How critical is that raised installation (for heat dissipation I assume)? Is it worth it to desolder the flush-mounted ones and replace them with a set mounted with Marc's tongue-depressor elevated mounting trick?

Leave them as is. No need to raise any component on White Oak Audio boards.

 

[MarkWComer]

I have started on the back plane boards. I overlooked the suggestion from Marc's excellent videos about mounting the 0.33 Ohm 3W resistors raised up a bit from the boards, and instead mounted them flush to the boards as shown in the WO Assembly Notes.

How critical is that raised installation (for heat dissipation I assume)? Is it worth it to desolder the flush-mounted ones and replace them with a set mounted with Marc's tongue-depressor elevated mounting trick?

Leave them as is. No need to raise any component on White Oak Audio boards.

The idea of raising the emitter resistors was my thinking that big resistors generate big heat. Raising them wasn’t necessary, just a personal quirk, I thought that raising them would increase airflow. An offbeat idea, I guess, but what the hell- didn’t hurt anything!

 

[Gepetto]

The idea of raising the emitter resistors was my thinking that big resistors generate big heat. Raising them wasn’t necessary, just a personal quirk, I thought that raising them would increase airflow. An offbeat idea, I guess, but what the hell- didn’t hurt anything!

It does no harm but is not necessary either...

 

[jle]

My PL400 total rebuild is moving along slowly but nicely. It's nice to be able to take my time, triple-checking things as I go. This is a "from the ground up" build, starting with a new chassis, donor 8-fin heat sinks (instead of the 4-fin heat sinks I started with) a transplanted transformer and the Watts Abundant protection. The PL400 is being built up on the new chassis, taking parts from my original PL400 as needed (like the heat sinks for the bias transistors, etc.)

I have read everything I can find about the RCA inputs in these forums (fora?), watched videos and read documentation. I got new RCA input jacks that can be installed without making electrical contact with the chassis (I will be testing and confirming that). My question concerns the copper plate at the RCA input jacks in my original PL400. One comment said that had to be preserved, but I don't see the need. The input jacks will receive their ground connection from the control board 2L and 2R. Do I also need to transplant the copper plate from my old PL400 input jacks to the new one?

 

[Gepetto]

My PL400 total rebuild is moving along slowly but nicely. It's nice to be able to take my time, triple-checking things as I go. This is a "from the ground up" build, starting with a new chassis, donor 8-fin heat sinks (instead of the 4-fin heat sinks I started with) a transplanted transformer and the Watts Abundant protection. The PL400 is being built up on the new chassis, taking parts from my original PL400 as needed (like the heat sinks for the bias transistors, etc.)

I have read everything I can find about the RCA inputs in these forums (fora?), watched videos and read documentation. I got new RCA input jacks that can be installed without making electrical contact with the chassis (I will be testing and confirming that). My question concerns the copper plate at the RCA input jacks in my original PL400. One comment said that had to be preserved, but I don't see the need. The input jacks will receive their ground connection from the control board 2L and 2R. Do I also need to transplant the copper plate from my old PL400 input jacks to the new one?

Short answer, no. Just insure that you also add a very short jumper connection between the shells (ground connection) of the 2 RCAs as they enter the chassis. That is the function that the copper plate served.

 

[jle]

Short answer, no. Just insure that you also add a very short jumper connection between the shells (ground connection) of the 2 RCAs as they enter the chassis. That is the function that the copper plate served.

So, 2L and 2R thereby get tied together, correct?