New Member: Planning my PL400 rebuild

J

jle

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Older than I act, younger than I look
#1
In the process of revamping my stereo system, I dug out my trusty PL400. It is an early 4-fin Series 1 (the big caps are mounted to the chassis left side wall using band clamps). The exterior is in pristine shape. While the interior looks fine, I have not plugged it in (and don’t plan to without some new caps!).

By way of background, I have been a solder jockey since 1968 when I built a HeathKit stereo receiver. I have done recaps on various pieces of stereo and recording equipment (just starting a recap of a McIntosh C22 preamp and of a Linn Lingo turntable power supply). I built a Moog Synthesizer clone that featured my first (and probably last!) adventure into surface mounting. I only trashed the pads of 1 PCB during that learning process. I built a replica of a Fender VibroVerb amp (from a kit) that worked perfectly the first time I plugged it in.

I use Kester 24-6337-0027 solder, Core Size 66, 63/37 Alloy, 0.031" at 600 degrees (but can go higher if it is needed) and a Hakko FX888D soldering station. I have a Siglent SDM3055 5.5 Digit Digital Multimeter.

This background may be important for my first question below.

I am planning a full White Oak upgrade to include:
  • PL400 LED Light Board RevC
  • PL400-15K-CAP-ASSY-CLMP Capacitor Assembly (that one matches my caps)
  • PL400-700 Bus Bar Assembly
  • PL400-700 Bridge Snubber Kit (with bridge rectifier included)
  • PL400-BACKE-COMP-KIT full comp Backplane Kit.
  • PL14_20 RegG1 Dual Mono Control Board Kit.
I have a few questions before I place my order:
  • The Backplane Kit is described as requiring “very advanced skill levels and more sophisticated assembly and test equipment to be successful.” Based on my background that I described above, should I be tackling this part of the upgrade? I have the “nerves of steel” but also enough humility to know what not to tackle. Thoughts?
  • What is the Phoenix Connector Option (for the PL14_20 RegG1) – why would I need that?
  • Do I need to order any of the Output Transistors (I am hoping they are already included in the parts listed above)
  • Do I need a Watts Abundant speaker protection board or will my speakers be safe enough after these upgrades?
  • I do not plan on installing a meter sensitivity switch, so I assume that I therefore have no need for the PL400-LBC-HARNESS. Is that correct?
  • Do I need the PL400-700 Backplane Wire Kit? What is it for?
Phew! Sorry for the long post (no I'm not). I know asking multiple questions in one post can be befuddling, but I see that there are many fuddled participants in this forum, so I am hopeful.

Thanks in advance!

-Jon
 
mr_rye89

mr_rye89

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I got by with a multimeter, variac, and dim bulb tester for my two WOPL builds. Yes you have to buy the output transistors and they're not cheap but White Oak is selling them cheaper than Mouser or Digi Key. A big hot iron (60 watt) is recommended for those backplane boards as they soak a lot of heat, yes you need the wire as it connects the power supply and boards together, the DC protect board is also a good idea. For me the hardest part is soldering the PEM nuts in the back plane. I also forget to install wires and components so it's good to double/triple check your work.

Some more guys here will chime in with stuff I'm missing...
 
mr_rye89

mr_rye89

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Eh mine's not but I did have issues. My build threads are there for the world to see....

Look at Eric's (Hexis22) build threads, that's how to do it. My threads are kinda not how to do it
 
Hexis22

Hexis22

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#6
See below for answers to some of your questions:
  • The Backplane Kit is described as requiring “very advanced skill levels and more sophisticated assembly and test equipment to be successful.” Based on my background that I described above, should I be tackling this part of the upgrade? I have the “nerves of steel” but also enough humility to know what not to tackle. Thoughts?
    • Your Hakko Iron only has a 65W handle and may present challenges when soldering PEM nuts into the backplane boards. 80W is recommended with a 3mm chisel tip.
    • Soldering backplane board components and PEM nuts requires significant level of patience and technique for robust connections.
  • What is the Phoenix Connector Option (for the PL14_20 RegG1) – why would I need that?
    • Phoenix connectors are highly recommended and make test and assembly of the control board into the amp much easier.
  • Do I need to order any of the Output Transistors (I am hoping they are already included in the parts listed above)
    • You will need to order output transistors separate from other components.
  • Do I need a Watts Abundant speaker protection board or will my speakers be safe enough after these upgrades?
    • DCP board is recommended and also eliminates turn On/Off thump at the speaker outputs.
  • I do not plan on installing a meter sensitivity switch, so I assume that I therefore have no need for the PL400-LBC-HARNESS. Is that correct?
    • Correct, no need for this harness if you're not installing a meter sensitivity switch
  • Do I need the PL400-700 Backplane Wire Kit? What is it for?
    • Yes, this wire kit is used to assemble the backplane boards to the amp and includes very high quality MIL spec wire.
 
Last edited:
mlucitt

mlucitt

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Additionally, you will need the experience of the folks who chimed in above. No one gets it right the first time, ask questions and be ready to show us high resolution pictures. We have collectively made every mistake possible, so you don't have to. You still get the satisfaction of doing the WOPL Upgrade yourself, but asking questions, even dumb ones, will leave you with more hair at the end.
 
J

jle

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Hexis22 said:
Your Hakko Iron only has a 65W handle and may present challenges when soldering PEM nuts into the backplane boards. 80W is recommended with a 3mm chisel tip.
Click to expand...
I think that my Hakko Iron had its feelings hurt by your comments, as it chose last night to quit on me. I'll replace it with something heftier as you suggest.

I am nearly done memorizing every posting and every photo that you provided on your PL400's rebirth (along with those of several others in this group). While "Forewarned is Forearmed," I am confident that I will find new and exciting ways to solder my way into trouble, but am comforted to know that fellow travelers are here to pick me up, dust me off and set me back on my path.

I think I just exceeded my monthly allotment of metaphors.

-Jon
 
J

jle

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mr_rye89 said:
I got by with a multimeter, variac, and dim bulb tester for my two WOPL builds...
Click to expand...
A Variac has been on my "To Do" list for quite some time. Is one required to do a proper WOPL 400 makeover? I suspect that flying blind without one and doing a "check twice then cross your fingers" may not be the best approach. I an guessing that a Variac would be needed for some of the tests and checks during assembly. What should I look for in selecting one?

-Jon
 
M

Mohawk

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#20
Jle,

Referring to what Snif said....

There are basically 2 versions of the 400.
An early design that had limited cooling, known as the "4fin 400". And the later that had the heatsinks "wrap" around each row of outputs.
I believe the design change was to accommodate a change in how amplifiers were tested at sustainable max output.
The early design couldn't cut it !

M
 
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