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Spec 2 Salvaged

Is that a sine wave being amplified? What frequency? (I can't see the 'scope controls well enough to determine the sweep rate.)
 
rhodus said:
Well, I've been checking out this scope and here is what I have...the left channel starts clipping at just above 41 volts (210 watts). The right channel sounds terrible at just above 31.5 volts (124 watts) and shows this waveform....

Can anyone tell me what this means?
View attachment 1694679
Click to expand...
I'm at work right now but yes, it is a perfect sine wave until just above 31.5 volts. I can get more info when I get to my shop later. If this helps, I drew what the sine wave turns into @ 31.5 volts. Excuse my artwork, lucky I have a day job....IMG_20191209_082049462 (1).jpg
 
Watthour said:
Is that a sine wave being amplified? What frequency? (I can't see the 'scope controls well enough to determine the sweep rate.)
Click to expand...
It is a 1000hz sine tone from youtube. Volts/div is 10. Time/div is .5 Here are some pics closer up...IMG_20191209_173656016.jpg IMG_20191209_173739955.jpg
 
This might be better?
https://www.szynalski.com/tone-generator/
Check out the scope and familiarize yourself by connecting the SG/computer to the scope only. This will let you warm up to the scope controls.
Start with and good 1khz sine wave at just above min gain from the SG.

Maybe you did that already?
The one channel is adjusted and went per the SM?

You may of got the limit trimmers hooked up. Try to get them untangled by running the signal in at at that 33 volt spot and turn the trimmers full clockwise, or CCW to get the sine wave back. Then max them out in the direction that will keep them from ever limiting the signal.
Re check per the procedure but make sure the sine stays as you go past the voltage limit. Now you can start over.
Then start the adjustment over after making notes on which way they turn to get the sine wave to clip.
I think they turn opposite of each other, which makes it easy to hook them up..

Or copy the trimmer positions of the good channel? And recheck?
 
Last edited:
zebulon1 said:
This might be better?
https://www.szynalski.com/tone-generator/
Check out the scope and familiarize yourself by connecting the SG/computer to the scope only. This will let you warm up to the scope controls.
Start with and good 1khz sine wave at just above min gain from the SG.

Maybe you did that already?
The one channel is adjusted and went per the SM?

You may of got the limit trimmers hooked up. Try to get them untangled by running the signal in at at that 33 volt spot and turn the trimmers full clockwise, or CCW to get the sine wave back. Then max them out in the direction that will keep them from ever limiting the signal.
Re check per the procedure but make sure the sine stays as you go past the voltage limit. Now you can start over.
Then start the adjustment over after making notes on which way they turn to get the sine wave to clip.
I think they turn opposite of each other, which makes it easy to hook them up..
Click to expand...
Thanks, I will get back on it tomorrow afternoon. I have Christmas duties tonight. I haven't made any limiter adjustments yet. I just hooked up the scope and tested as is. The left channel has a good sine wave up to 41 volts, then starts clipping. The right channel is good up to 31.5 volts and then instantly switches to the waveform in my drawing above, as if something in the amp shuts down. When I decrease the gain the sinewave returns....
 
I'm sure it's the the trimmer settings.
Maybe set them to center before checking again.
 
zebulon1 said:
I'm sure it's the the trimmer settings.
Maybe set them to center before checking again.
Click to expand...
As expected, you were right my friend. I fiddled around with the limiters on both amps and got this thing singing! 250 wpc is no problem. Nice sine wave both channels. Installed power cord, repaired meter light circuit, now I'm ready to put it back together.....IMG_20191210_154144628_HDR.jpg
 
I love the pioneer symbol and the blue filter caps. Makes the amp look nice through the grill when you see it. That way the amp titillates two senses, through sound to your ears and visual to your eyes. Very nice work you did on that amp. I would have thought from the first pic it was a parts unit. Great job! Wow! Just impressed. What are your specialities? Amps, Tuners, Receivers, Reels?
 
I have zero electronics knowledge but I've been extremely mechanically inclined over my lifetime and have dove into some things I had no clue about and did well at. However, this is a whole different ball game. Just the schematics are confusing let alone have no clue how to understand. Too busy right now but when I retire in a few years I thought of taking an electronics degree type of course at the local college to learn how to do this. I've always liked tinkering with stuff. I don't even have basic knowledge so I can't get into this like some on here. My RT-909 needs a total restore stripped down and start from the bottom up but I'd never attempt that. I can see trying the EQ as everything is easy to get to. But I'd need a list of the caps to buy for it and my TX-9800 that also looks easy to get to the boards to do it myself. That I'll attempt. But what to look for on the caps I have no clue and don't want to order the wrong stuff from mouser. I asked this week if anyone on here has a thread that shows what cap lists you'd need for different pieces of Pioneer Stereo from this fluroscan era. Not sure there is one. I did some searches but was empty handed.
 
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