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  1. C

    Pioneer S-W700 Subwoofer

    Ok. May have found another issue. Cable and connector CN-7502 is a problem. Wires to the R and L out, Ground ref. and B1+ were all broken. Could be the reason why no sound output. Moving the pc board often while I have been trying to repair it, may have caused the cable to break. It broke...
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    Pioneer S-W700 Subwoofer

    Not much surface area after I made the cut. Only a small solder pad to work with. 10 AWG pretty stiff. Can I go from connector to connector solder pads of Q7512 to Q7524? The foil runs from collector to collector. Tinned and soldered the copper link from collector to collector solder pads of...
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    Pioneer S-W700 Subwoofer

    Thank you so much for your insight. I am going to locate the copper wire and do the repair as you illustrated. No there was no output from the sub at all. I purchased a new coaxial cable and verified its condition whit a working subwoofer. I will double check the Q7514 C-E resistance as well...
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    Pioneer S-W700 Subwoofer

    There are no replacement boards. How can I repair the copper foil on this board? The damage runs al the way from in front of Q7512 emiiter to in front of the collector of Q7514.
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    Pioneer S-W700 Subwoofer

    Ok. Everything back together. Took it off my test current limiter( 100 watt incandescant bulb). Plugged directly to 110 power. Unit comes on,fan stays on all the time, and no output from the the speakers.
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    Pioneer S-W700 Subwoofer

    Thanks for your reply. Trying to get up my nerves and patience. Hopefully will start today.
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    Pioneer S-W700 Subwoofer

    I thought about that but wasn't sure how to proceed. Solid core wire? What size?
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    Pioneer S-W700 Subwoofer

    I have been troubleshooting the Pioneer S-W700 sub woofer for sometime now off and on. I have replaced several components on the Power Mod. F100, board #AWZ5389 board. The board has some foil raised near the right channel output transistors. Foil completely off and copper trace exposed. I would...
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    Sansui 7070 Left and Right Output Issue

    The original issue was the output on the right channel was always low. The watt meter movement was always less on the right channel. If you isolated the right you could tell. When I first brought the unit out of storage, I replaced caps on the output board. Still had the problem until I...
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    Sansui 7070 Left and Right Output Issue

    Ok. Thanks for your help. Now both channel are outputting the same. Before the left channel was always low compared to the right. Sounds like a vintage 70's receiver should sound. Thanks again.
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    Sansui 7070 Left and Right Output Issue

    Tried readjusting the DC current bias per the service manual. Still could not get 30 mv. 24.6 mv on both channels. ).0 volts at the speaker inputs on both channels were dead on. Should I worry about the 24.6 mv bias instead of the 30 mv? If yes, then I should try to find the new 4.7 k ohm...
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    Sansui 7070 Left and Right Output Issue

    Replaced R33 and R34. Both 180 ohms. Rechecked the operation with the new resistors. Comes out of protect mode and speaker relays kick in. Both channels work great. I just need to find new pots so I can set the proper current bias for the output transistors. Thanks for your help.
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    Sansui 7070 Left and Right Output Issue

    I can post a page of the schematic if you would like?
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    Sansui 7070 Left and Right Output Issue

    I checked the supply voltage (+44.8 @ output NPN transistor collectors) and -44.8 at PNP collectors output transistors.. They both were ok. I then followed the +44 back on to the F-2624 driver board . I then checked (the + side of C07 & C08) and it read Neg. 15.2v on C07 instead of +44. C08...
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    Sansui 7070 Left and Right Output Issue

    To measure the rail voltages, I have to measure pins 5, 6, 27, and 28 of the driver board, (F-2624). Its difficult to measure these with the board installed. I am trying to figure out where else to measure the +44 v and the -44 v. Kind of disappointed in myself and seems like a whole day...
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    Sansui 7070 Left and Right Output Issue

    I thought I knew what I was doing too until I resoldered some connections and trimmed some that look like they were touching on the power supply board. Emitter and collector solder joints for TR01, TR02 were touching and TR03 was close but not touching. Now I got no relay kicking on. Could I...
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    Sansui 7070 Left and Right Output Issue

    I have a Sansui 7070 receiver that I originally purchased in 1976. Used it for about 10 years before putting it away in leu of a AV receiver. I recently brought it out of storage. It still works, but the right channel has low output. I replaced caps on the F2624 driver circuit board. When I...
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