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Pioneer S-W700 Subwoofer

coastman49

May 1, 2022
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Ok. I see it. Looks like the board for $167 has all the components. What do you think?
 

73's de Edd

Aug 21, 2015
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If you find the FWB defective and have put A.C. to them and possibly the filters, that's what is to be expecteld .
Also the need of the use of an inline Test Lamp and interpretation of its use.
ALONG with only an instant of power up as I emphasized in the last troubleshooting of readings.
 

73's de Edd

Aug 21, 2015
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Sir coastman49 . . . . . . . . (Iz u reeeeely 73 'ish)


Waiting to hear about the FWB status.

If being at fault . . .LIKELY . . . I think that only the mere pittance of the purchase of a new FWB will initially be needed . . . and not the expense of all new output transistors . . . AS OF YET.
Then, I can guide you in, on the testing of the PROBABLY good LEFT OUTPUT channel . . .less its blown outputs, which transistors, will be pulled out and left vacated. (As well as the RIGHT CHANNELS also.)

Then a comparative testing between the expected workable LEFT channel and the " foil burning " RIGHT CHANNEL, to get it normal again.

FREEBIE !
I have the schematics for that unit EXCEPTING the bonehead that scanned them overlooked the bottom 10% of the schematic.
I am in the process of getting verbal info and re-plotting in that missing portion.
Thaaaaaaaaaaaaaaaaaaasit !

73's de Edd . . . . .




The FIRST empirical rule of intelligent tinkering . . . . . . . . is to save ALL of the loose parts.

.
 

coastman49

May 1, 2022
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Ok I have the Service manual. I can send you copies. What page? I will continue testing sometime today. Got a family medical crisis I am dealing with. Will pull the FWB and check the caps later today. Let me know what page of the manual you are needing as well. Thanks thus far for you expert help.

I did measure the output of the FWB Ground to pin 1 = 39.8 vdc; ground to pin 4 - 3.7 vdc. Capacitor C1201 is the filter across that leg. I think it was the one that smoked. Do I still need to pull the FWB to verify it is bad? I guess I need to do that anyway to replace it. Only 4.5 vac across pins 2 and 3. All measurements made with 100 watt incandescent bulb in the circuit.

I didn't see intro above. Yes I am 73 ish as of may 21st.lol.
 
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73's de Edd

Aug 21, 2015
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Sir coastman49 . . . . .

Ok I have the Service manual. I can send you copies. What page?

I am missing the VERY bottom 10% of the page which contains the two AUDIO OUTPUT AMPLIFIER STAGES
FLAG MARKINGS OF PROTECT AND TEMP are centered within that crossing cluster of circuitry's hoz connecting lines .

FWB Ground to pin 1 = 39.8 vdc;
Just about what I would expect, with the imposed limitation of AC power input from the test lamp being used

ground to pin 4 - 3.7 vdc.
At least we have just a widdle of Bee Minus-sus-ses supply but not the EXPECTED complementary - 39.8
C1202 must be reduced down to 5 micro farads now.

Only 4.5 vac across pins 2 and 3
HOW ? HOW? HOW? . . . . .CAN THAT BE with + 38.8 DC output at pin 1 of FWB ?
AC from the power transformer comes in at the BLUE rectangles with GREEN the rectangle being AC ground .

Do I still need to pull the FWB to verify it is bad?
. . . . . .VERY GOOD IDEA . . . . . .due to circuitry interconnections.

REPEAT . . . . . . for referencing convenience . . .

upload_2022-6-1_5-41-45-png.55308



73's de Edd . . . . .


My credo . . . . .
I'd rather have something . . . . . and not need it . . . . . than not have it . . . . . when I do need it.




.
 

coastman49

May 1, 2022
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I have attached the schematic containing the driver and output transistors. I will go back a re do the measurements and pull the rectifier.
 

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73's de Edd

Aug 21, 2015
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This also drops out the bottom 10% so I am still correcting . . .s l o w l y .
 

coastman49

May 1, 2022
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I think this is the rest of it.
 

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coastman49

May 1, 2022
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Sorry uploaded wrong schematic. Here is the bottom 10 percent of sch-2
 

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coastman49

May 1, 2022
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Took the FWB rectifier out of the circuit and measured using my multimeter on diode check. With black lead on the negative pin (4) and red lead on pin 3=OL, pin 2= OL, and pin 1= OL. Reversed the leads and , Red lead on pin 4 and black on pin 3=.531, pin 2=.535 and pin 1=.997.
 

73's de Edd

Aug 21, 2015
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Sir coastman49 . . . .

GOOD SHOW ! . . . . .Lo o o o o o o king Go o o o o o o o d
. . . . . . now, with maybe no expense of the purchase of another FWB.

Comparing the schematic snippet to the internal FWB component equivalency, we can see that you tested internal diodes "B" and "D" and found no back resistance / leakage.
And then found that both of those diodes had good forward conducting junctions of 535 and 531 millivolts. Then, finally, the 2 in series diode
junctions having a reading of 997 millivolts .
(The last variance in readings . . . if you were expecting the added diode voltages . . . was because the measurement parameters shifted in the meter supplied current and voltages due to the measurement of a single diode junction versus a series pair of diode junctions . )

Now do a complete test of ALL of the rest of the units diodes, by placing a meter probe on #1 and go thru that same sequence of tests, in that way, you are then getting "A" and "C" sections readings.

And finally, do a test from 2-3 and then do it with a probe polarity swap.

That last test is where you will find the advantage of having a pulled FW block . . . . if being in circuit . . .that is where you would be getting a low reading due to the BLUE RECTANGLES power transformer winding shunting those terminals. (Post 30's full schema referencing )


upload_2022-6-8_5-25-51.png

If all is well, guess that its time to do a fresh solder tinning of the block and then reinstall with new solder , leaving a magnificent workmanship, work of electronic craftsmanship art after a bristle brush + solvent cleaning of the joints and a final solvent + Q-tip polishing of the joints + dry Q-tip polishing . ( Now, looks like they are being chrome plated . . . don't they ? )

Then I would move on to the C1202 Negative supply filter E-capacitor and pull it . Then pull its companion C1201 and install it in place of the pulled unit.
Then go thru a test lamp installed power up and I think that you will then have a working MINUS 39'ish power supply voltage . . . . . as you formerly had with the former PLUS 39'ish volt supply.
( Now disconnected to make this test )

PULLING those brutes . . .

Position the chassis so that gravity will assist you, in having the caps solder joints, being face up and topside.
Then . . . 1 of two options . . .
Add solder to the two terminals to make heat retaining BLOBS then get one blob into a liquid solder state and then move to the other to heat it to the same liquid state .
E..v..e..n..t..u..a..l..l..y the heat will be retained enough by the appropriately timed swaps, such that both blobs, now being in a liquid state will then permit you to pull y the cap downwards and free from the board.
Then, option 2 . . . .
Usually, being because your soldering Iron didn't have enough THERMAL HEAT OOOMPH . . . .
You heat one solder joint , while pulling the extweme***** end of the capacitor case toward the unheated joint.
At one point in the liquification of that heated joint, your tilting effort should let you feel some very slight freeing movement of that heated terminal.
Freeze further movement at that instant and remove the soldering irons heat until the joint has solidified in that new slightly lower position.
Move soldering iron heat to the other terminal and use the same procedure to get its contribution of a micro movement
After an appropriate number of heat transitions plus terminal movements you should have a final freed terminal.
BONUS . . .no circuit board / nor / foil damage.

***** A typo of mine at 100 + wpm speed . . . . . but it looked so . . . . .tongue tied . . . . .Elmer Fudd 'ish . . . .that I just had to leave it !

Waiting for MINUS 39'ish volts . . . . .

Thaaaaaaaaaaaaaaaasit . . .

73's de Edd . . . . .


I went to a massage parlor . . . . . . . but then found out that it was self-service.


.
 
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coastman49

May 1, 2022
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Ok. Did the Red probe on 1+. Got OL on pin, 2, 3 and 4 with red probe on 1+. Also did 2 and 3, swapped polarity and got same reading both directions, OL. Waiting to hear from you before i move on to the capacitor test.

Next: On to the capacitor test , pulling C1202 and replacing i with C1201, after your reply.
 

73's de Edd

Aug 21, 2015
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Did the Red probe on 1+ . . . . . . . .

But it looks like that you didn't do the BLACK probe on pin 1 . . . TO THEN . . . . .do that sequence of testing, to be able to get the two "A" and "C" diodes "500 'ish millivolts readings " + plus the series diodes . . . . .~ 1 volt 'ish reading.

Thaaaaaaaaaaaaaaaaaaaaaaaaasit . . . .
 

coastman49

May 1, 2022
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I thought I did that one earlier. Anyhow here it is: Ok. Did the Black probe on 1+. Got .542 on pin, 2, .537, pin 3 and 1.003 on pin 4 with Black probe on 1+. Also did 2 and 3, swapped polarity and got same reading both directions, OL.

I think this id what you asked me to do. Let me know . Thanks Edd.
 

73's de Edd

Aug 21, 2015
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GREEEEEEEEEEEEAT . . . . .(a la Tony The Tiger)
Now . . .that all is well . . . . go fer the install of the already known good E cap in the negative supply .
 
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