Sansui 6060 Question

Discussion in 'Exclusively Sansui' started by misterguitar, Apr 24, 2017.

  1. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Glad to hear you are making progress with it, l would try re cleaning the switches first.

    If both channels are dead on phono then most likely a power supply issue to that board or a selector switch problem.
     
  2. misterguitar

    misterguitar AK Subscriber Subscriber

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    cleaned the selector switch an relubed. ok so I'm checking power supply to the board. looks like its the red wire and a black ground wire headed over to the common ground. I get 48 volts off the red wire. I can't seem to tell from the schematic what the power supply voltage to the phono amp should be. But if I hit the terminator als of the phono amp transistors they all read 48 volts to ground! which is odd!! It looks like this model has three supply viktages of three different windings. One for the lamps, one for the power transistors and the other for every thing else. Where would be a good point to read rhe voltages of the various rails? I'd like to clear up the power supply as ok or not ok. I'm trying to trace the various connectors between boards on the schematic but the peint is a bit fuzzy. I'm taking that manual up to kinkos to get it printed in large size for my aging eyes. two years ago I didn't need glasses at all. now I can't see anything close up. I feel old and crusty now!
     
  3. misterguitar

    misterguitar AK Subscriber Subscriber

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    Sorry for all the typos . I'm working off my tiny iphone till I can fix my home pc!
     
  4. misterguitar

    misterguitar AK Subscriber Subscriber

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    48 volts would seem to high? The windings on the transformer are listed as 32volts? sounds like the voltage regulation circuit is not working maybee?? How would I deduce from the schematic what the regulated rail voltage should be? I am reading my schuler electrinics book to try to figure this out myself..
     
  5. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Don't forget the transformer winding outputs are AC voltages and all voltages in receiver minus the lamp supply will be DC. Here is a link that explains all of this well.

    http://www.bristolwatch.com/ele/basic_ac_rectification.htm

    The amplifier rails will be unregulated DC, lamps usually unrectified (AC) and the supply to all other sections regulated DC. I just downloaded the schematic and as you say it is hopeless, l cannot decipher any of the voltages either, very blurry.
     
  6. misterguitar

    misterguitar AK Subscriber Subscriber

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    Yeah this is kind of a pickle for me. Sad to say I'm used to the Marantz stuff which is a bit better documented. Its hard to even to begin logical troubleshooting when you have no idea what the input voltage supply to the board is as everything calculates off that. I guess I could just test every single component on the phono/mic amp board for function. My gut says its in the regulated power supply. Which may be why the low filter button and muting button cause almost speaker blowing pops when pushed in or out. But I did just go out to staples and printed that schematic at 36x24! and like magic the voltages in those orang circles are visible now! Not sure how much help they will be though.
     

    Attached Files:

  7. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Yes l know what you mean, some of the service manual copies make it very hard. Some of the manufacturers don't even list many of the voltages. I like Pioneer manuals the best. At least you have something to reference now.

    Great idea on the large copy, l remember doing this many times years ago tracing circuit faults in cars.
     
  8. misterguitar

    misterguitar AK Subscriber Subscriber

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    well so far I have lifted and tested all the bridge diodes one at a time. all are good. pulled all the new electrolytic caps I put in the PS circuit. they all test correct. checking all the resistors and the sd313 transistors now
     
  9. misterguitar

    misterguitar AK Subscriber Subscriber

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    it would appear the power supply is ok. the components all check out to spec. does anybody else out there have a 6060? If so could you take a voltage reading off the red wire that feeds both the tone amp board and phono amp or as Samsui calls it the equalizer board. seriously this thing is driving me batty!Im kinda wishing I had not taken this one on! I'm running out of things to check. Just pulled the 2sc1222 and 2sc1313 transistors on the phono board and they test good. Grrrrr
     
  10. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    I don't have my 6060 anymore, sorry. I wonder if the transistor leg voltages are correct on the equaliser board, does the service manual provide these values?

    It is still strange that neither channel on phono is working, is there a way you can check for continuity between equaliser outputs and pre amp inputs when phono is selected on selector switch?

    Does the mic input work?
     
  11. misterguitar

    misterguitar AK Subscriber Subscriber

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    Hmm. I'm currently on vacation and away from the receiver. All good questions you ask. I brought the schematic for the power supply, a scientific calculator, a notebook and this book with me lol. https://www.amazon.com/Engineering-...&sr=8-4&keywords=engineering+circuit+analysis I decide if Sansui would not tell me what the correct voltage from the supply to the tone and phono board are I'll just have to calculate it the old fashioned way! I should be back home this coming Friday or Saturday. but the lady is getting anxious to get it back and I may have to admit defeat and send it to another tech in the area to figure it out. <<GASP!>> I am going to order replacements for the two 2SD313 transistors in the power supply. Both are on heat sinks and I figure it can't hurt to replace them since they get hot!
     
  12. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    I bet it's just what you want to be looking at on vacation :rolleyes:. I hope you can get it figured out but in any case she should be very happy with all that you have done so far.

    Good call on the regulator transistors on the power supply, l usually use TIP41C's for the replacements as l can get these locally.

    Have a great time away :thumbsup:.
     
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  13. misterguitar

    misterguitar AK Subscriber Subscriber

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    Ok. back from vacation. Man this thing is driving me crazy. Replaced both regulator transistors with TIP41C's. No change. Tested both transistors. Both are good. Checked the transformer windings. The two 32 volt windings measure out at 34 volts each. My line voltage is a bit high at 122 volts so that makes sense. The 24.8 volt windings measured 27 volts each. Checked all the diodes again in both bridge rectifiers. All good. Pulled all the electrolytic caps off the power supply. All test accurately within spec. So just to step back and review...

    What was done
    Replaced power transistors(SD188A and 2SB545) with MJ21193 and MJ21194. (Originals were mixed. One was a Marantz!)
    Replaced both differential pairs (2SA726) with KSA992FTA (Known sketchy transistors)
    Replaced all electrolytics on power, driver, tone, and phono boards with exact same voltage/capacitance using Nichicon and Elna Electrolytics (Muse, KG, Fine Gold SILMIC II, etc.)
    Replaced tantalum's on phono board with exact same volt/cap Elna SLIMIC II
    Replaced fuse resistors R01-R04 with 6.8 ohm 1/4 watt metal film resistors
    Replaced transistors on tone board (2SC1313) with KSC1845FTA(Known sketchy transistors)
    Replaced C704 .033 cap across power switch with ecq-u2a333ML (Original cap had a cracked case and coating)
    Replaced transistors on phono board (2SC1222 and 2sc1313) with KSC1845FTA (out of desperation to get the phono amp working!)
    Replaced both regulator transistors (2SD313) with TIP41C.

    Current sysmptoms-operation
    I was able to set the bias sucesfully.
    Receiver powers up, lights come on, relay clicks as expected
    Radio tuner works but sounds bad. Kind of tiny and out of phase or something. Both AM and FM work. Lots of static and some kind of interference in the background.
    Auxiliary works with CD player, but sounds bad. Much like radio
    Phono section is nothing but silence.

    Hitting the Audio muting switch produces a thunderous pop in the speakers. No matter what input setting. If the speaker selector is set to off, hitting the audio muting switch throws amp temporarily into protection mode. If the speakers are set to a it just makes the loud pop like its about to blow the speakers.

    Hitting the low frequency filter makes a loud pop/clicking sound. not as bad as the audio muting sound, but close! High filter does not do this? (WTF?)

    The lights dim on the unit when the popping sound happens on either the low filter or audio muting switch for the duration of the pop.

    I'm about to pull my hair out. At this point I've tried or done everything I know to do. My voltage analysis of the power circuit was a flop.

    Where should I turn from here? Give up and buy her a fixed one on ebay and admit defeat? lol
     
  14. Skywatcher

    Skywatcher AK Subscriber Subscriber

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    Sounds similar to a problem I came across a few years ago where a Zener had shorted. With your lights dimming something is definitely drawing some current momentarily, and leaking some otherwise. Also check for a bad ground somewhere. It wouldn't hurt to check all the 10D1 diodes as well.
     
  15. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Good advice from Skywatcher, yes sounds like something strange is going on, l would start at the power supply checking all diodes and resistors for spec.
     
  16. Skywatcher

    Skywatcher AK Subscriber Subscriber

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    Check the fuses, and the fuse clips. If it was as grungy as you described, there may be a film, and/or corrosion on the fuses and clips. Plus squeeze the clips so the fuses will be clamped tighter. That would explain why you get the "pop" on the low filter, but not the high filter because the low frequencies draw more current. I had a "dimming lights" problem once and as it turns out it was "just" the fuse and weak fuse clips. And I had an intermittent channel which also turned out to be a cracked fuse clip.
     
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  17. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    +1 on this, l have experienced the fuse clips losing their tension also.
     
  18. misterguitar

    misterguitar AK Subscriber Subscriber

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    Ok. Good things to check.I did manage to use photoshop and extrapolate some of the voltage readings from the original circuit diagram in the manual with orange circles. I came up with this. Specifically the voltage coming off the supply at L headed towards the phono amp was what I needed. The internals of the supply appear to be different as far as cap values resistor values, etc. So I don't trust those to be accurate. Particularly the measurements off the Zeiners, etc. But I figure the voltages out to other main modules (Filter caps, power amp transistors, etc.) would be the same. I checked these and they all seem to be in line. All measured out to within a few volts. So I THINK the power supply may be ok. So I started checking the driver board. On this board all electrolytic were swapped for like Silmic and Nichicon Muse. The Diff pair where swapped for KSA992F. Gain was a bit lower than the originals. The 1uf's were swapped for identical spec 1uf WIMA films. I connected the receiver to my 8 ohm dummy loads and fired it up. let it settle in and warm up. Checked voltages on the driver board as compared to the Sansui Schematic. Some voltages were off. I don't recall exactly but I know some of the other voltage checks were off. I was not sure if this was a result of the swap of the diff pair for transistors with slightly different characteristics or not. I will remeasure and post accurate measures tonight. I did notice the driver board has 4 fuse resistors. And the power supply still has two large fuse resistors, and the tone Amp has a single fuse resistors. I have ordered metal film replacements for those and they are on the way so we can eliminate them as a source of the problem. I did clean and check both the fuse clips and the fuse ends. Checked for continuity and those seem fine. for giggles I'm going to solder together some 9 volt batteries tonight with a resistor to pull and check the zeiners in the power supply just to be sure. But yeah same symptoms still. And the light dimming did make me think there must be something drawing a LOT of current. Had the audio muting switch apart and it is perfectly clean. I have a tenma audio signal generator and a counter and scope available. Would it be advisable to inject a signal at the input of the power amp section just to look and see what comes out on the scope? It is convienent on this one as there is a plug connector that has both left and right channels from the toneamp that plugs straight on the driver board. My suspicion is since both those switches are causing the popping the problem is on the tone amp board. Logical?
    on t 6060 circuit analysis.PNG 6060 circuit analysis driver.PNG
     
  19. Skywatcher

    Skywatcher AK Subscriber Subscriber

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    If you pull the fuse resistors and check them, you will more than likely find they have drifted up in value. But if by chance they are still within spec, then something else is happening. But either way replace them when the new ones arrive.
     
  20. misterguitar

    misterguitar AK Subscriber Subscriber

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    Ok just got it all back together. I don't have my new fuse resistors yet. So I did some more poking around. So I did the voltage checks on the phono amp stage on on board F-2644. Collector voltage on TR01 should be 1.1 volt. It's 38 volts!!!!! Collector voltage on TR03 should be 17 volts. But its also 37 volts!!!! Supply voltage coming in connector L on the schematic is 41 volts. I pulled the connector for G and 03 on that board just to amke sure voltage isn't being backfed from some malfunction in the tone amp through the selector switch but nope. What would cause that much voltage in those places? wrong transistor orientation? I double checked that. 6060 phono amp board.JPG 6060 Phono schematic.JPG
     

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