Speaker Selector Switch Pioneer A-676 fixable?

Discussion in 'Pioneer Audio' started by H2ohm, Apr 7, 2018.

  1. H2ohm

    H2ohm New Member

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    Hello everyone, my first post and day on AK!

    I did some searching around and no luck on what I need to ask!

    My question is my selector switch works on A, but not on B only if I slightly turn it towards the A+B position but where it does not click in the A+B position.

    This is a 1991 SD model amp (120V North American) the part # is ASD1004 (S401) for (SD type Pioneer A-676).

    Are these switches a bit mechanical where one can try to align (if there are metal parts within) it so the B channel will work?

    I only had one pair to test each channel, and is it possible that the A+B will work (I should have tested it) on its own even though the B position was off a bit?

    The relay does click in the: Off/A/B/A+B.

    The amp sustained a bit of a mishap where the Phono selector switch was pushed into the amp...it clicks fine but I do not use Phono so I am not too worried on that right now.

    Any help/knowledge share if the switch is replaceable with a good quality one or do I need the exact model?

    I did email Pioneer to ask for the part, I was not sure if the A-717 switch might work.

    I thank you all in advance for the help and look forward to learning and gaining some new friends on AK!
     

     

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  2. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    deoxit the switch thoroughly. Then test again. You could be hitting a friction cleaned path through the corrosion.
     
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  3. restorer-john

    restorer-john Addicted Member

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    There are three relays, one for speakers A, one for Speakers B and one for the headphones.

    The two speaker relays are activated by the rotary switch on this PCB behind the front panel, clean as suggested, check solder joints on rear of PCB and confirm the flat ribbon cable is seated correctly in the edge connector at each end (front switch and terminal plate rear):

    speaker switch ass.JPG

    I would also check the rear speaker terminal PCB as the two speaker relays are mounted on that PCB and if at any point in the past, the amplifier was rested on it's back, the large speaker terminals can crack the PCB tracks (red circle) and prevent the relay/s operating.

    speaker term pcb.JPG
     
    Last edited: Apr 7, 2018
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  4. H2ohm

    H2ohm New Member

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    I hope so Mark! That is what I was thinking. I will give that the first priority for sure! Thanks for that!
     
  5. H2ohm

    H2ohm New Member

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    Okay I will take the front off (first time at doing this but will consult that manual and try to be careful) and have at it. Do you know if A+B then would work even if B is sort of bad at the moment? I use the A+B all the time to run two sets of speakers from it. But, I will do this soon and report back and thank you for your help John.
     
  6. restorer-john

    restorer-john Addicted Member

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    A+B switches both relays on. If A+B works at the moment, but B alone doesn't, the problem is 100% the rotary switch contacts or solder joints on the switch PCB.
     
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  7. H2ohm

    H2ohm New Member

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    Very good - thank you kindly on that info. I will get at this tomorrow and post. There is a wire running from 'somewhere' to the one B side with a horrible gob of white goop, I will get a photo of that as I am not sure if it is tied into anything or what the last owner did to warrant that wire. I think the bottom comes off this so I might get to see where it is coming from right now the top view it is under the power supply transformer. Thanks mate - I'll report back soon on this one!
     
  8. H2ohm

    H2ohm New Member

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    Hi guys...here is what happened! LOL Yeah, oh oh!

    I got the face-plate off and used deoxit on the switch...the relays were responding when going through the positions while on and I did turn it off to work the stuff in. I hooked up 6 ohm speakers 100W 90dB to the A side and 8 ohm bookshelf Wharfedale Valdus 100's? to the B side (I hope by not having the same ohms that this caused my further issues!). I heard music for the B side but again only when I slightly turned it more toward the A+B selection, then while on I worked the switch somewhat slowly to each position but noticed I do not hear the relays anymore! So, I am wondering (probably they are gone) if some could please tell me of a video on how to test for open relays (if that is the condition that I caused)?

    I mentioned about a black wire that runs from the center tap of the two large caps to the speaker terminal's B side (see photos)...there is white goop on it too where it goes to the circuit board (does not seem to be heat sink paste but might be)?

    I just am laughing as I know lining up the knobs let alone the Speaker switch is going to be tough - this is my very first trial and error fix. I do own a scope but I am learning, it is a Hitachi 100mhz dual channel and is calibrated and works great - just do not know if I need this for testing the relays.

    Just to get at the two relays, I would have to de-solder stuff to get the boards apart (see photos)!

    Not sure if buying parts is worth the hassle, I can just part it out or something, but I will not give up, just the basement looks like a mess and I hope my cats do not play hockey with some of the pieces! LOL

    Help! ha ha (I think the very least I need two relays and the switch) to get it working - fuses are fine and no burn marks or smell from any of the boards, the amp looks really clean!

    Thanks everyone for helping out - I fumbled but hope to kick a field goal! LOL
     

    Attached Files:

  9. H2ohm

    H2ohm New Member

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    Location:
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    On the speaker circuit board (where all the terminals are) I so far tested two 100 ohm 1W resistors that are shorted (R901, R902) these are parallel with the coils in the circuit I believe. I will paste the schematic from hi-fi the speaker terminal board.

    The speaker switch is gone/broke so I need that for sure...the components all check fine - so switch is bad.

    I do not know which setting to put on my multi-meter to test the 3 relays that stopped clicking, it has lots of choices (not fluke brand - it is Mastercraft). So, I tried to use it on Ohms and touched across the NO relay and it read nothing with all 3 relays (Ry 901{ASR112}, Ry 902 {ASR112}, Ry 903 {ASR1005}. The code on the Ry901 and Ry902 are Omron G5R-2223-PG (obsolete) but, think from Mouser that these will be a good replacement (found from internet) G2RG-2A4 / DPST / NO Type / 5A 24VDC.

    How does one measure or test the 3.15A 125V fuses? Do I leave them in the holders or pry them out and use the meter? Not sure which setting for meter - ohms? But I will look up testing fuses. No sure if these are Slow Blow if I need some but the coil/spring looking wire in them look intact.

    Note: I made a correction on this post - the resistors that are shorted are 100 ohm/1W not the 10 ohm/2W sorry about that!

    upload_2018-4-10_6-30-46.png
     
    Last edited: Apr 17, 2018 at 6:58 AM

     

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  10. H2ohm

    H2ohm New Member

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    @restorer-john

    Those boards you post on here are great. I lost one of the guys helping out...must be pretty busy! But, I made the switch worse as it is not clicking in place anymore. All caps (2) and resistors are fine on the switches PCB.

    The Speaker Terminal Board might be in luck, right now only the two 100 ohm/1W resistors are shorted that are in parallel with the coils. The rest of the resistors are fine. I did not check the caps yet. But, since I did not have the volume up when I was an idiot turning the switch back and forth working in the deoxit (with the power on!) I think that is all that may have happened.

    Can a person take a 9V battery and touch it to the coil end of each relay to hear a click? These are NO ones. Or do I have to take them out and then test them some how.

    I think I have a variable power source for breadboarding and since these are 24VDC could I maybe put 12VDC onto the two pins where the coil is located on those relays to see if they were not shot?

    There are no visible cracks to the board and the fuses were not blown, no burn marks, so I may just have to try to take apart that switch (A-310,A-717 might work but no luck finding something else to use as my speaker selection switch) and try to fix it.

    All solder joints are not cold w/ no cracks in the areas that this fault caused.

    Anyone trust other places for buying resistors and or fuses? I am not sure if Mouser has a minimum order?

    DSCF6119.JPG DSCF6120.JPG DSCF6121.JPG DSCF6122.JPG DSCF6123.JPG DSCF6126.JPG DSCF6127.JPG DSCF6128.JPG DSCF6129.JPG
     
  11. restorer-john

    restorer-john Addicted Member

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    I think the speaker selector switch should be easy enough to find. It's a four position Alps unit. Have a look on the bay. 3P4T rotary PCB mount with straight (non fluted) shaft.
     
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  12. H2ohm

    H2ohm New Member

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    Outstanding John I thank you for your help! I will go check now.

    Do you know if fuses in this amp are fast blow or slow blow. I found some 2.5A 250VDC fast blow fuses in a bunch of compiled parts I bought long ago. There are two that are 3.15A 125VDC they have a 'spring' type center rather than a straight wire!

    :thumbsup::thumbsup:
     
  13. restorer-john

    restorer-john Addicted Member

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    A 'spring type' centre wire suggests a slow blow. The S/M may show it. T means time or slow blow. F means fast blow.
     
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  14. H2ohm

    H2ohm New Member

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    Location:
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    The S/M does not tell as far as I see from it. But thanks for teaching me that info. When I order any fuses I will do the slow blow.

    Was that switch a 4P or 3P John? I found some in Canada 3P4T. They are not like the original shaft though...but I can either grind it down and add a wad of paper no big deal!! The length is 2 cm from the end where the nut start to go on to the end of the dial. I can probably make something longer if need be. I watched this video on what glue is best and for flex especially on those plastic tabs were are to press down to release the face cover would work as I broke one off.

    I found the piece of plastic that broke off where the volume knob goes and the piece the broke off where the MC switch is...if this JB Weld original holds I might just get away with putting this nice amp back together and make it look like new. It ran so well too - just that lining the dials is going to be a bit tricky and there are two screws that hold down the face plate PCB that is going to be tricky to line up (patience)!

    I was hoping someone could let me know on that circuit on the Speaker Assembly if those 100 ohm 1W resistors were replaced if that would cure the relay issue and make them work again?

    I dug out my variable volt supply and could try putting maybe 9 volts across the coil to see if that will make it click?! All the other resistors are fine...not sure what setting you put the meter on if you energize the amp and look for values of voltage and/or current...still lots to learn but I think it looks favorable to save this one!

    Talk at you later!
     
  15. H2ohm

    H2ohm New Member

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    No cracks. I am getting a reading with the ohm meter of around 1.080 kohms across the coils in each relay. I found two of resistors that are shorted R901 and R902 the ones that are in parallel to the coils in the schematic. All other resistors are fine, I am not sure how to check all the caps or transistors (no sure if you need them in the circuit or test them in circuit with the power off?).

    I ordered the parts and the switch to the speaker selection because it is so loose you barely feel it clicking in place.

    I believe when I used the ohm meter that I got infinite when I tested the pins of each relay are are opposite to the pin where the coil is located (so 4 pins). I think I got the 1.080 kohm reading when I tested the 4 pins diagonally. Right now I am not sure where to find replacements - mouser.ca has something close but it is 8A G2RG-2A4 and I need 5A 24DCV G5RG-2232-PG (would need two of those), the other relay is 5A 24VDC 40AC.




    [​IMG] Coil is where the two pins are (right)...




    For RY901 - ASR112-B (G5R-2232-PG 24VDC - 5A - 40VAC) I measure w/Ohm Meter:

    > Across the coil = 1.073 k Ohms
    > Farthest two pins from coil (measured across) = 14 k Ohms and it keeps increasing!
    > No other readings in other various lead tests (diagonal etc...)


    For RY902 - ASR112-B (G5R-2232-PG 24VDC - 5A - 40VAC) I measure w/Ohm Meter:

    > Across the coil = 1.08 k Ohms
    > Farthest two pins from the coil (measured across) = 14k Ohms and it keeps increasing!
    > When looking at the crappy diagram I did above - the top lead from the coil to the top lead of the farthest pin measured = 5 M Ohms Decreasing!
    > When looking at the diagram - the bottom two furthest pins measured = 1 M Ohms Decreasing!


    For RY903 - ASR1005 (DEC DH2SU 24VDC - 2A - 120VAC] I measure:

    > Across the coil = 1.082 k Ohms
    > Farthest two pins from coil (measured across) = 14 k Ohms and it keeps climbing!
    > No other readings in other various lead tests


    I am hoping this means the relays are okay and that 2 resistors are the ones that made all the relays from clicking when turning on the amp!

    Photo 6122 is the Speaker Assembly Board and there are no cracks that @restorer-john mentioned to check! Whew...
    Photo 6114 is the Omron relay codes for Relay 901 and 902 (Pioneer code ASR112-B or just ASR112)

    I seek help and hope reassurance that my relays are fine and that the 2 resistors in parallel with two inductor type coils (bigger bare ones) are the issue!
     

    Attached Files:

    Last edited: Apr 12, 2018
  16. H2ohm

    H2ohm New Member

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    Location:
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    On the power boards I am not sure if I am to turn on the power to test (is the meter to be set to DC voltage?). There is a green one for each channel and a black one for each side. I got 0.5 ohms on some readings on both green and black but I have to check the S/M to see if it says which one is NPN and PNP or both of either!!!

    But going through most of the boards except the phono (too hidden) all components seem fine. I got good readings 0.3 on those which 5W power resistors are they called?

    So, I think it might be safe to say two shorted resistors are preventing the relays from working - new switch ordered from Digikey. Original is mangled while trying to get the stupid thing off the board - need better component pullers as there were 15 pins too close together to do one at a time while pulling on the switch to separate it from the PCB!

    Switch PCB will need a small fix as the trace came off where one is not showing a good contact - will scratch to expose a bit and solder the part in when it comes and it should be fine (I hope)!
     

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