WOPL update for PL400

WOPL Sniffer

WOPL Sniffer

Veteran and General Yakker
#41
Joined
Aug 10, 2015
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11,522
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Minnie-Soda
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Screw it
#41
2 prong non-polar are what you need. Don't monkey around with the grounded bullshit and 3 prong plugs. After a couple hundred amps done between us, don't worry about them being "SAFE". They are safe and you won't upset the ground scheme. Joe has already said, don't monkey with the scheme or you'll pay with ground loops and other shit. I think you already know from other posts that the three prong stuff aint the way to go... I'm just saying.... It's been tried and..... whatever.


https://www.amazon.com/Woods-0288-N...&refinements=p_89:Woods&s=lamps-light&sr=1-15
 
J!m

J!m

Veteran and General Yakker
#42
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Dec 24, 2019
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11,148
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Connecticut
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BOT
#42
FYI Sony and Panasonic replacement cords are two-prong, non-polarized.

I replaced the hack job cord on the first (scam) KA-9100 I got with a Panasonic replacement.

Only issue was the original Kenwood cord was brown and the new one was black.

Maybe you can find brown if that’s what you need.

I believe the wire was a bit heavier as well, since the strain relief was a bear to get back together.
 
BlueCrab

BlueCrab

Journeyman
#45
Joined
Nov 10, 2019
Messages
229
#45
Construction continues - when I get a chance. So far, no serious issues and I've been following the instructions. Here are some notes.

1) As stated earlier, I stripped the chassis down to nothing to treat some beginning corrosion. The transformer had some. I looked at the suggestion to use a straw or heat shrink to cover the transformer mounting bolts, but the hole through the laminations did not have enough clearance to allow either a straw or heat shrink covered bolt to pass.

2) My solder station - a Weller EC1002 60 watt station - has done just fine. An 80 watt or greater station was recommended, but I haven't had any issues. I do keep everything clean - particularly the sponge. I set it to 650 F for soldering on the circuit cards, only stepping it up to 680 - 700 F when there is a large thermal mass.

3) The WOPL kits are great. So nice have so many parts - particularly resistors and diodes - already formed. Never had it so good. I also sprung for the backplane wire kit. Glad I did. First rate wire.
IMG_0537.JPEG IMG_0544.JPEG IMG_0548.JPEG IMG_0550.JPEG IMG_0551.JPEG
 
BlueCrab

BlueCrab

Journeyman
#47
Joined
Nov 10, 2019
Messages
229
#47
Everything is proceeding smoothly and then an "Ah Shit". First, I tested the power supply - both B+ & B-, without connecting either the WOPL PL400 backplane or the WOPL PL14-20 control board. It tested fine - about +/- 82 vdc. Then I connected power to both the backplane and the control board and power up through a Dim bulb tester. Just the bottom row of output transistors (drivers) were installed. 1 amp fuses installed. Everything came up normally - right and left output voltages were 0.0 mVDC & 0.4 mVDC respectively. Both B+ & B- were around 80vdc. Checked +15 on the control board. It's okay. Checked -15 on the control board - it's okay. And then, as I was removing the probe from the -15vdc test point on the control board, the micro-clip touched the heat sink of Q2 and I saw a little tiny arc. -15 died instantly. The heat sink is at the same potential as the collector of Q2, which is about -78vdc. Troubleshooting, I found a blown pico fuse on the right channel back plane. I replaced this (fortunately the kit provided extras), but the damage was done.
IMG_0552.JPEG
I wasn't sure what else was killed, but suspected the voltage regulator VR2, a TL431, the zener diode, D81, and both Op Amps, U1L & U1R. So I removed and replaced all. That fixed it.

In order to prevent this from happening again, I put a bit of heat shrink on the heat sink tine that is close to this test point. But now I check the -15 from pin 4 of the op amps. This is at the top of the board and is easy to get to.

I've now added all the backplane transistors and have set the bias. Everything is good. Life is good - for the moment.

A couple of notes:
1) The clearance between the top mounting bolt and nut (which is connected to the chassis) of the PL14-20 board and the heat sink of Q1 is tight. The heat sink has +80vdc on it. Ensure there is adequate clearance. This applies to the bottom mount as well.
IMG_0553.JPEG

2) There is an error is the Assembly Notes for PL400 BackPlane Rev C PCB document, step 31, where it instructs to install only the pre-drivers in locations XQ11 & XQ12. Must be a carry-over from the PL700 as there are no XQ11 & XQ12s. Should be XQ7 & XQ8.

3) The light kit - it would be nice if the instructions labeled what goes to PAD1 through PAD5. And that matched the photos in the instruction. (The instructions discuss PAD1, PAD2, PAD3, PAD8 and PAD9). The instructions must show an earlier version of the board and silk screen. But in the end, it was easy enough to figure out.

4) Can't say enough good things about the kits. Everything is first rate. Often extra parts - nuts, screws, diodes, sil-pads, pico fuses - are included. Boy, does this help.

IMG_0555.JPEG
 
BlueCrab

BlueCrab

Journeyman
#54
Joined
Nov 10, 2019
Messages
229
#54
Anyone have covers for the output transistors? Not wild about having them exposed with about 160vdc difference between them. I'll make something if I can't find originals.
 
Gepetto

Gepetto

Administrator
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#55
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May 15, 2011
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14,091
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Sterling, MA
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Old 'Arn Enthusiast
#55
BlueCrab said:
Anyone have covers for the output transistors? Not wild about having them exposed with about 160vdc difference between them. I'll make something if I can't find originals.
Click to expand...
The 4 fin covers are likely to be rarer than the 8 fin version
 
BlueCrab

BlueCrab

Journeyman
#56
Joined
Nov 10, 2019
Messages
229
#56
I finally managed to get it all put together. Today I married the front panel to the rest of the chassis. That's when I determined the two filter caps were mounted too far forward to allow the front panel with meters to mount (I did measure this, but somehow got it wrong.). Fortunately I had marked where the original caps had been, so I remounted the new caps in the same location - plus a smidget deeper. Just in case you're wondering, these caps can't use the old caps chassis mounts. Now the front panel fits.

Connected a signal generator to the input, connected a couple of 10W 8 ohm (I know - they are woefully inadequate, but it's all I have at the moment) resistors to the output and used my PicoScope 2000 (a PC based oscilloscope) to check the output. I kept the input voltage to a minimum just to be nice to those resistors as at the moment, I just want to check basic functionality. So - it all works. At least to the extent I can test at the moment. Sine wave input from 20Hz to 20kHz looks good, square wave input produces a square wave at the output. All is good so far.

Absolutely no noise or hum, but I haven't connected any speakers yet. I don't have any - not here. This has been one of my winter projects and I did this WOPL upgrade in our little condo in Florida. My real workshop is up in Maryland. Florida is nicer to my arthritis. My wife kindly puts up with my messing up the bedroom - half the project is scattered over the bed. It's better than having a car's transmission on the dining room table.

Still looking for ideas to cover those output transistors. Don't fancy getting my fingers across them.
 
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