Mark goes at it again... just bought a PL700/II!

[MarkWComer]

Well, in order to make sure I break even more rules, will probably use a different color for the wires- not enough purple!

 

[MarkWComer]

More work, and less Mr. Rogers Videos

Yeah, would have this done a looong time ago!
But, the videos are for the benefit of those who know less than I, but I find that I may be leading sheep over a cliff...

 

[Gepetto]

Well, in order to make sure I break even more rules, will probably use a different color for the wires- not enough purple!

Since I know you installed backplanes, I know you have open F_B- vias on each backplane board. The instructions were written for a novice that did not install backplanes, just meter replacements.

 

[MarkWComer]

Since I know you installed backplanes, I know you have open F_B- vias on each backplane board. The instructions were written for a novice that did not install backplanes, just meter replacements.

Yes, I considered that, went to bed last night with the “how am I gonna do this?” worm in my brain, so another half hour of lost sleep. I looked through my box of wiring, and found enough to finish.
All that remains now is to calibrate the display and burn it in, put the Mr. Rogers sweater on, and edit the LAST* video.

*- Next to last- there will be an epilogue, “things I could have done better,” encouragements to the intrepid, blah-blah-blah...

 

[mlucitt]

I would like to see the video of you calibrating the display. I want to see how you find LED 31...
That sounds like a good title for a Sci-Fi movie. Do you read me HAL? HAL? The voice of HAL was Douglas Rain, he died in 2018.

 

[Gepetto]

Yes, I considered that, went to bed last night with the “how am I gonna do this?” worm in my brain, so another half hour of lost sleep. I looked through my box of wiring, and found enough to finish.
All that remains now is to calibrate the display and burn it in, put the Mr. Rogers sweater on, and edit the LAST* video.

*- Next to last- there will be an epilogue, “things I could have done better,” encouragements to the intrepid, blah-blah-blah...

Hey Mark
I have been told my assembly instructions are a good cure for insomnia

 

[MarkWComer]

I would like to see the video of you calibrating the display. I want to see how you find LED 31...
That sounds like a good title for a Sci-Fi movie. Do you read me HAL? HAL? The voice of HAL was Douglas Rain, he died in 2018.

Yeah... I’d like to see that myself!

Don’t look for LED 31, look for 0db / 350 watts on the scale.

I bought a cheezy Chinesey wave generator for the calibration, I can’t get 53v output. Tried a variety of things, but at last resort I may go back to using the laptop and make a file in Audacity. The laptop will have a higher output, so I should be able to reach the 53v output level that way.

 

[MarkWComer]

Just to clarify something- 53v RMS represents 350w into 8Ω. Got that, Ohm’s law. Is this what I read from a standard DVM? I attached the DVM to the speaker outputs, set the DVM to the 200vAC range. This is correct? Or not?

 

[MarkWComer]

That sounds like a good title for a Sci-Fi movie. Do you read me HAL? HAL?

A friend suggested I watch “2001” while tripping. BAD idea!
Watching concrete boil, clouds change colors, and shag pile carpets wave like ocean water was far more entertaining.

 

[Gepetto]

Just to clarify something- 53v RMS represents 350w into 8Ω. Got that, Ohm’s law. Is this what I read from a standard DVM? I attached the DVM to the speaker outputs, set the DVM to the 200vAC range. This is correct? Or not?

If your meter measures true RMS yes. No load needed to set the meter calibration.

 

[WOPL Sniffer]

 

[MarkWComer]

If your meter measures true RMS yes. No load needed to set the meter calibration.

Looks like it does...

 

[MarkWComer]

View attachment 44598

Only the pre-WOPLs go kaboom!

 

[laatsch55]

Au contraire!!

 

[MarkWComer]

Au contraire!!

Yeah, some issues can be forced...

 

[mlucitt]

If it can be blown up, Lee can do it.

 

[MarkWComer]

So, unable to get 53v...

The cheezy-Chinesey wave generator shows a max 2v output, I get ~17v output at speaker terminals.

Max. οutput of my laptop shows 1v, and I get 37v output (~170w) at speaker terminals.

Consistent output- both channels, I went for the 37v and calibrated the meters to 1 segment before 175w (yes, I know this is wrong). Odd that the laptop’s lower output level yielded higher output at the speaker terminals...

I suspect I have some bad output transistors, but find it odd that I get the same values from channel to channel. Back when I shorted pad 11/12 on the backplane, I wonder if I took something other than driver circuit components and the picos, but again- this would have shown on the left channel only.

Tested with the coupling in “normal” and “direct” positions (should not have any significant effect regardless).

Power supply is balanced (-100,+100v). Played about 2 minutes of audio, this is far below the output of the 400! Cut the audio playing short, obviously.

EDIT...
This better NOT be those emitter resistors...

 

[WOPL Sniffer]

Mark, is this a WOPL???

 

[laatsch55]

2 volts peak to peak ain't even close Mark. You need 1.75 rms at the inputs to get max out.

 

[MarkWComer]

Mark, is this a WOPL???

Yup... KABOOM!