sx-939 static

Discussion in 'Pioneer Audio' started by kcmoejoe, Oct 28, 2009.

  1. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    sx-939 static / protection issues

    I'm new here to the board but looks like I've come to the right place for vintage receiver help. I'm hoping someone can guide me in the right direction.

    I picked up an sx-939 that looks really clean. I've used deoxit on the switched and knobs and reflowing solder joints that looked slightly cracked.

    I can tune to FM station and get good sound, but it does have lots of loud static (mostly in the left channel) and the protect relay was kicking in and out and then died apparently. I can jumper pin 4 & 9 on the protect. board and get it to kick on and work but still get the static (guessing C1384 transistor is bad?), also when I remove the jumper connectors on the back for L/R I get complete silence on both channels.

    From reading, I gather that the SX-1010 is almost exactly the same as my SX-939 unit? so am I safe to assume the parts list for rebuilding are the same?

    sounds like I need to do a rebuild with parts for the protection board and maybe also to power supply board...what do you think? (one or both?).

    here is the list I found for the ps board, but I couldn't locate a list for the protection board AWM-062...

    ------------------------------------
    sx-1010 AWR054 power supply rebuild

    --------------------------------------------------------------------------------

    I'll get a under 5(? w/o shipping) buck list together to do the power supply pass transistors and a few resistors. That's how I conquered maddarts power supply problem.

    I should have just stressed that from the start.

    Q4 2sb507
    one 512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

    Q1 Q7 2sd313
    two 512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54 ea

    Q8 2sc1384 (ecb)
    one 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
    or one 512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 (preferred, the current is below 0.1 amp)

    Q5 Q6 2sa628 (BCE)
    two 512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    Q2 Q3 2sc869 (ecb)
    two 512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    D8 D9 wz-032
    two 512-1N5257B Fairchild 33 V, 0.5W zener $0.05 ea

    D10 wz-014
    one 512-1N5244B Fairchild 14 V, 0.5W Zener $0.05

    two ten ohms 1/4 watt metal film 660-MF1/4DC10R0F 0.06 ea
    one 3.3 ohms 1/4 watt metal film 660-MF1/4DC3R30F 0.06

    was the power supply recapped?
    ok, here's the caps:
    C7 & C8 470uf (80v) 100v 647-UPW2A471MHD $1.87 ea
    C10, C11 100uf (63v) 100v 647-UPW2A101MHD $0.87 ea
    C12 & C13 100uf (35v) 63v 647-UPW1J101MPD1TD $0.37 ea
    C14 47uf 50v 647-UPW1H470MED $0.25
    C18 1000uf (35v) 50v 647-UPW1H102MHD1CV $0.98
    C19 220uf (16v) 35v 647-UPW1V221MPD $0.41
    C20 & C21 2200uf 10v 647-UPW1A222MHD $0.80 ea

    extra parts just in case somebody's looking :
    D1 D2 D3 D4 SIB01 100v 1amp
    D5 D6 D7 1S1885 100v 1amp
    512-1n4004 conventional rectifier 1a 400v $0.06 ea
    __________________

    Thanks for any advice and guidance!

    Joe
     
    Last edited: Feb 14, 2011

     

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  2. markthefixer

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

    Messages:
    21,012
    Location:
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    It's somewhere in the preamp, jhard wiring ON on the protection is verboten... that can start house fires.

    If you haven't gotten the service manual (PM ME).
    Invest in a paper reproduction for the best clarity, from Rick at stereomanuals.com

    remove the jumpers, put the protect back as it should be, and see with the jumpers out, if the relay kicks back on.

    Then put the jumpers in and see what happens. If the protect leaves the speakers connected, follow the block diagram on page 8 of the pdf, to see if anything on the front panel affects the problem (like bypassing the tone controls or the switchable filters)

    If it stays in protection with the jumpers out, and the hard wiring of the protect circuit removed, then we have some voltages to read, IF you can follow the manual, it's the power supply voltages(pins 4(+13v),5(+35v),6(+47v),10(-13v),11(-25v) on awr-052 board), and the amplifier output voltages (pins 1 & 3 on awm-062 board)as found on the input of the protection board.
    Don't worry, if you need guidance in finding or reading them, I will help...

    It may be the 2sa725's in the control amp, or if the noise continues or the unit stays in protection with the jumpers out, the 2sc1451's in the power amp.

    Either transistor is inexpensive, with shipping costing more than the parts, and the work involved in getting to them.

    No blanket rebuilds yet.
     
    Last edited: Nov 7, 2010
  3. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    so far....

    I removed the L/R jumpers and at first I didn't have speakers hooked up and I heard a click about 6 sec. and then a second one a few seconds later.

    I then attached speakers and tried again (with jumpers removed) and get nothing, no click, no sound, no static.

    now with jumpers inserted I get the same thing above...nothing at all.

    so I take it, it is staying in protection. now to take some meter readings...

    I get these readings, and while taking them it's popping in and out randomly for a few seconds, sound in the R channel, mostly loud static and pops in the left.

    4(+13.2v) 5(+35.4v) 6(+45.8v) 10(-13.1v) 11(-27.8v) on the AWR-052 board.

    1(not stable reading...jumping all around) 3(0.19v) on the AWM-062 board.
     
    Last edited: Oct 29, 2009
  4. markthefixer

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

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    21,012
    Location:
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    Ok, the amp is sick, 0.19 is pretty poor, but the other is definitely gone...

    Not a big problem, couple of transistors and caps, probably be able to leave the outputs alone.

    The power supply voltages look good, and the protection is doing it's job, so the work would be purely preventative - but considering the costs of shipping versus parts, IF you're going to want to do them anyway.

    but there's no rush, in fact sunday night should be considered your parts order deadline now, due to ship / shipping / weekend delays...

    I'm impressed, nailed those readings just fine...

    You had a list of awr-054 parts, 939 has either a awr-052 or an awr-056, your next exercise is to see if the same parts are in your 939, if not, modify the list keeping the same format and I will look it over, and add the replacements to it.

    The protection is awm-062, the SAME as in the 1010. most protection is the same, 4 caps, 2 transistors and a diode added.

    Q6
    512-KSD1616ALBU to-92 ecb x60v 1a 0.75w 160mhz 135-400hfe $0.09
    edit 2/7/201 this 1616 is 60v not 160 but is ok here

    Q7
    512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
    add diode to pins 9(unbanded end) & 10(banded end) going off the board
    512-1n4004 conventional rectifier 1a 400v $0.06 ea
    c1 c2 0.22uf unk volts (0.22uf/50v non-polarized film cap)
    598-DSF050J224 $0.14? ea
    c3 c4 330uf 6v (330uf/10v)
    647-UPW1A331MPD $0.20 ea
    c5 4.7 25 (4.7uf/50v)
    647-UPW1H4R7MDD $0.12 ea
    c6 100uf 16v(100uf/50v)
    647-UPW1H101MPD $0.22 ea

    amplifier awh-030

    uh oh, HERE'S the problem!! : Q7 & Q8 are 2sc1451's....

    q1, q2, q3, q4 2sa726 BCE to-92 bce 50 .1a .2w 500hfe 100mhz
    512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

    q5, q6 2sb527 unk pkg/ BCE 110v 0.8a 1w 55-300hfe
    512-KSA1220AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.39

    q7, q8 2sc1451 ebc
    this recommended transistor may get hot in this application, it depends upon the voltage across R35
    512-KSC2310YBU TO-92L ecb 150v .05a .8w 100mhz 40-240hfe $0.11 ea
    if it does get hot, use this one:
    512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
    it may be a good idea to get both...

    q9, q10 2sd381 bce to-220 120v 3a 20w 40-250hfe 45mhz
    512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

    q11, q12 2sb536 bce to-220 120v 3a 20w 40-250hfe 40mhz
    512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

    as far as capacitors, you will need to check if c1,c2,c3,c4 are ALL used and what are their values - ymmv
    c1,c2 0.47/25 598-DSF050J474 0.47uf 50v poly cap $0.29 ea
    c3,c4 1/50 647-UPW1H010MDD $0.12 ea
    c5,c6 33uf/16v 647-UPW1H330MED 33uf/50v $0.24 ea
    c11,c12 330uf/10v 647-UPW1A331MPD 330uf/10v $0.20 ea
     
    Last edited: Feb 7, 2010
  5. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    thanks alot Mark, of so if I follow you correctly above your listing the parts I need to order to fix the protection and amplifier boards as well as parts for the power supply which I'll list below, some were different from what was listed in the service manual.

    difference between the sx-1010 (awr-054) and sx-939 (awr-052) power supply parts:

    sx-1010
    sx-939 in bold

    Q4 2sb507
    one 512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

    Q1 Q7(no Q7 sx-939) 2sd313
    two 512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54 ea

    Q8 2sc1384 (ecb) (no Q8 sx-939)
    one 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
    or one 512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 (preferred, the current is below 0.1 amp)

    Q5 Q6 2sa628 (BCE) (sx-939: Q5 2sa720-Q or R) (sx-939: Q6 2sd313-E or D)
    two 512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    Q2 Q3 2sc869 (ecb) (sx-939: 2sc1318-Q or R)
    two 512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    D8 D9 wz-032 (sx-939: D8 SR3AM-8) (D9 1S1885 SIB01-01)
    two 512-1N5257B Fairchild 33 V, 0.5W zener $0.05 ea

    D10 wz-014 (sx-939: 1S1885 SIB01-01)
    one 512-1N5244B Fairchild 14 V, 0.5W Zener $0.05

    two ten ohms 1/4 watt metal film 660-MF1/4DC10R0F 0.06 ea
    one 3.3 ohms 1/4 watt metal film 660-MF1/4DC3R30F 0.06
    (I was unsure about these above resistors? the 939 has R1-R21 listed.)


    was the power supply recapped?
    ok, here's the caps:
    C7 & C8 470uf (80v) 100v 647-UPW2A471MHD $1.87 ea
    C10, C11 100uf (63v) 100v 647-UPW2A101MHD $0.87 ea
    C12 & C13 100uf (35v) 63v 647-UPW1J101MPD1TD $0.37 ea
    C14 47uf 50v 647-UPW1H470MED $0.25
    C18 1000uf (35v) 50v 647-UPW1H102MHD1CV $0.98
    C19 220uf (16v) 35v 647-UPW1V221MPD $0.41
    C20 & C21 2200uf 10v 647-UPW1A222MHD $0.80 ea

    C7/C8 Ceramic 0.01 150v ACG-004-0
    C10 Ceramic 0.01 150v ACG-004-0
    C11 Electrolytic 47 63v CEA 470p 63
    C12 Electrolytic 47 50v CEA 470p 50
    C13 Electrolytic 470 80v ACH-038-0
    C14 Electrolytic 470 80v ACH-038-0
    C18 Electrolytic 47 16v CEA 470p 16
    C19/C20 Ceramic 0.001 50v CKDYF 102Z50
    C21 Electrolytic 47 50v CEA 470p 50


    extra parts just in case somebody's looking :
    D1 D2 D3 D4 SIB01 100v 1amp
    D5 D6 D7 1S1885 100v 1amp (sx939:SR3AM-8 100v 1amp)
    512-1n4004 conventional rectifier 1a 400v $0.06 ea
     
  6. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    thanks Mark, of so if I follow you correctly above your listing the parts I need to order to fix the protection and amplifier boards as well as parts for the power supply which I'll list below, some were different from the 1010 (AWR-054) list and what was listed in the 939 service manual.

    difference between the sx-1010 (awr-054) and sx-939 (awr-052) power supply parts:

    sx-1010
    sx-939 in bold

    Q4 2sb507
    one 512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54

    Q1 Q7(no Q7 sx-939) 2sd313
    two 512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54 ea

    Q8 2sc1384 (ecb) (no Q8 sx-939)
    one 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
    or one 512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 (preferred, the current is below 0.1 amp)

    Q5 Q6 2sa628 (BCE) (sx-939: Q5 2sa720-Q or R) (sx-939: Q6 2sd313-E or D)
    two 512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    Q2 Q3 2sc869 (ecb) (sx-939: 2sc1318-Q or R)
    two 512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea

    D8 D9 wz-032 (sx-939: D8 SR3AM-8) (D9 1S1885 SIB01-01)
    two 512-1N5257B Fairchild 33 V, 0.5W zener $0.05 ea

    D10 wz-014 (sx-939: 1S1885 SIB01-01)
    one 512-1N5244B Fairchild 14 V, 0.5W Zener $0.05

    two ten ohms 1/4 watt metal film 660-MF1/4DC10R0F 0.06 ea
    one 3.3 ohms 1/4 watt metal film 660-MF1/4DC3R30F 0.06
    (I was unsure about these above resistors? the 939 has R1-R21 listed.)


    was the power supply recapped?
    ok, here's the caps:
    C7 & C8 470uf (80v) 100v 647-UPW2A471MHD $1.87 ea
    C10, C11 100uf (63v) 100v 647-UPW2A101MHD $0.87 ea
    C12 & C13 100uf (35v) 63v 647-UPW1J101MPD1TD $0.37 ea
    C14 47uf 50v 647-UPW1H470MED $0.25
    C18 1000uf (35v) 50v 647-UPW1H102MHD1CV $0.98
    C19 220uf (16v) 35v 647-UPW1V221MPD $0.41
    C20 & C21 2200uf 10v 647-UPW1A222MHD $0.80 ea

    C7/C8 Ceramic 0.01 150v ACG-004-0
    C10 Ceramic 0.01 150v ACG-004-0
    C11 Electrolytic 47 63v CEA 470p 63
    C12 Electrolytic 47 50v CEA 470p 50
    C13 Electrolytic 470 80v ACH-038-0
    C14 Electrolytic 470 80v ACH-038-0
    C18 Electrolytic 47 16v CEA 470p 16
    C19/C20 Ceramic 0.001 50v CKDYF 102Z50
    C21 Electrolytic 47 50v CEA 470p 50


    extra parts just in case somebody's looking :
    D1 D2 D3 D4 SIB01 100v 1amp
    D5 D6 D7 1S1885 100v 1amp (sx939:SR3AM-8 100v 1amp)
    512-1n4004 conventional rectifier 1a 400v $0.06 ea
     

     

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  7. markthefixer

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

    Messages:
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    Some of that post addressed specific dead parts for that repair - the resistors. Transistors are all listed because they are inexpensive, as opposed to finding bad ones, and replacing them.

    The amp needs work, the rest of the parts are gravy, IF you want to do them & save shipping.

    these caps aren't covered above:
    C11 Electrolytic 47 63v CEA 470p 63

    647-UPW1J470MPD 47uf 63v $0.28 ea

    use a higher voltage (like a 50 for the 47/16) for "missing" caps.

    replace only electrolytic caps - mylar, ceramic etc don't dry out.
     
    Last edited: Jan 23, 2011
  8. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    I finally got around to getting the parts and sitting down this weekend to start replacing components on the awh-30 amp board. I guess I didn't have enough coffee because while trying to get to the amp I snapped a lead wire on D6 - if I read the manual right is a varistor (STV4H) ? it runs of the edge of the board to the black metal heatsink and attached by a screw to hold it down. Is there a fix for this or do I need to order a replacement at this point?

    [​IMG]
     
  9. markthefixer

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

    Messages:
    21,012
    Location:
    Bensenville,Illinois
    Whatever you do, until that is fixed,

    DON'T TURN ON THE POWER

    It will turn the outputs into a smoking ruin.

    I guess we don't repeat the warning about that part enough - it's fragile. ALways loosen the screw, separate it from the heatsink and let it float free - WITHOUT bending the leads near the body of the part. Those leads, as you see, are fragile and love to break - usually flush with the body.

    You're in luck, Pioneer actually has some in stock:
    http://parts.pioneerelectronics.com/part.asp?productNum=STV-4H

    The other alternative would have been to send it to me, and I excavate the epoxy 1/32" and solder small flexible wires onto the nubs, then epoxy the thing to hold it all together. I developed that as a last resort,(it takes a steady hand, and a lot of practice as well as a very careful - non intuitive procedure) then Pioneer actually got some back in stock, at 12.50 apiece.

    As it is, I would appreciate it if you could send it to me, and I would repair it (I developed a mold that fits it, the added wires etc and holds the epoxy in until it cures) and hold it in abeyance for a time when that is the only alternative left.

    If not, PLEASE DO NOT DISCARD THE OLD STV-4H. For ALL our sakes.....
     
    Last edited: Dec 6, 2009
  10. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    Thanks Mark...that's the least I can do (sending it to you to repair) since you've been helping me along with all of this. shoot me a PM with your address to mail it. In the meantime I'll place an order for a new one. thanks for the link!

    Do I need to keep the fabric insulator sleeves on both the wires? I'm assuming that doesn't come with a replacement.
     
    Last edited: Dec 6, 2009
  11. markthefixer

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

    Messages:
    21,012
    Location:
    Bensenville,Illinois

    Correct, retain the fabric insulator sleeves, you WILL need them.
    PM in works...
     

     

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  12. kcmoejoe

    kcmoejoe Active Member

    Messages:
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    Location:
    Kansas City, MO
  13. EchoWars

    EchoWars Hiding in Honduras

    Messages:
    28,407
    Location:
    Kansas City
    Encompass simply orders their parts from Pioneer, and if Pioneer shows they are out, looks like the last source for these devices is officially tits-up.

    Fun while it lasted. I should have known better than to reveal the source here in the forum. Even at that price someone decided to buy out the stock. Fuck.
     
  14. markthefixer

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

    Messages:
    21,012
    Location:
    Bensenville,Illinois
    Re: EchoWars.... DITTO...

    Send the busted one to me, I'll fix it faster than next year.... plus that date from Pioneer is not a guarantee....
     
  15. EchoWars

    EchoWars Hiding in Honduras

    Messages:
    28,407
    Location:
    Kansas City
    That date from Pioneer is someone's idea of a bad joke (or blatant ignorance). There is no source for these devices.
     
  16. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    thanks so far for the help guys, I canceled my order with them and Mark should be getting my broken part here in the next day or two.

    I have a couple questions with my component changing on the awh-030 amp board so far.

    Mark, you said q7, q8 2sc1451 ebc might get hot with the recommended transistor. I went ahead and ordered both parts you mentioned...should I start with the first one and see what the voltage is on R35 after I get everything back together?

    also, I'm a little confused on the capacitors...C1 on their now has polarity markings and the poly cap i ordered (598-DSF050J474) doesn't. Are these different? do I not have to worry which direction i place them? I've read that some capacitors don't have polarity. just wanna make certain I'm putting them in right.
     

     

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  17. EchoWars

    EchoWars Hiding in Honduras

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    Poly caps aren't polarized. Install whichever way trips yer trigger.
     
  18. markthefixer

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

    Messages:
    21,012
    Location:
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    R35 voltage could be (and mean) anything. R35 to ground, or across r35 are different things - which are usually immaterial unless something is radically wrong. Which wasn't the case with yours - it made sound, and added some pops.

    What I would do, is do one channel with the smaller 2310 and the other channel with the larger 2690, and see if the channels have a difference in the noise floor, or if the 2310 gets hot, or if even the 2690 gets hot (the 2690 can accept a heat sink if there's room) enough to "ouch" touch....

    I have used it, and it's cousins, in other amps at that equivalent point, without noise problems, but this is a first time for me with the 939 and this position in the circuit....

    BUT REMEMBER !!!!!!!!!!! NO POWER !!!!!!!!!!!!

    Not until the diode that I am going to fix is back in place.
     
  19. markthefixer

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

    Messages:
    21,012
    Location:
    Bensenville,Illinois
    Ok, picking up the thread again, the repaired STV-4H diode is in place after several different adventures, and the unit powered up on the dim bulb tester.

    When I inquired about the trial idle current settings while on the dim bulb tester, it turns out they were not done, it appears that this is news to him, so I'm looking for a thread to steer him to, to explain in more detail the setting of idle current and offset on a 939, first under the dim bulb tester to be SURE that turning up the idle current doesn't trigger a disaster, then when OK, setting idle currents and offset voltages as per the manual WITH the power plugged DIRECTLY into the wall outlet.

    thumbnail:

    mtf: with dim bulb tester connected:
    page 17 of the pdf manual

    1. no 8 ohm resistors in place of speakers needed. volume to zero
    2. connect dmm to pins 10 and a chassis ground,
    3. adjust vr1 for zero
    4. connect dmm to pins 50 & 44, adjust VR3 to read 50mv on the dmm
    (no sudden surges of light, maybe a little increase in brightness of dbt.)
    mtf: turn down VR3 to minimum after you get 50mv..
    now the other channel
    2. connect dmm to pins 25 and a chassis ground,
    3. adjust vr2 for zero
    4. connect dmm to pins 38 & 32, adjust VR4 to read 50mv on the dmm
    (no sudden surges of light, maybe a little increase in brightness of dbt.)
    mtf: turn down VR4 to minimum after you get 50mv..

    then if all is ok, disconnect d.b.t.

    with dim bulb tester DIS-connected, and unit plugged directly into wall:
    page 17 of the pdf manual

    1. no 8 ohm resistors in place of speakers needed. volume to zero
    2. connect dmm to pins 10 and a chassis ground,
    3. adjust vr1 for zero
    4. connect dmm to pins 50 & 44, adjust VR3 to read 50mv on the dmm

    now the other channel
    2. connect dmm to pins 25 and a chassis ground,
    3. adjust vr2 for zero
    4. connect dmm to pins 38 & 32, adjust VR4 to read 50mv on the dmm

    redo this (check) 20 minutes later waiting for things to stabilize.

    There is a picture on page 17 of the pdf with arrows pointing to the adjustments.
     
    Last edited: Jan 20, 2010
  20. kcmoejoe

    kcmoejoe Active Member

    Messages:
    106
    Location:
    Kansas City, MO
    ok, I'm following this fine, and have the manual. When it says dmm on 50 and 44 this means using a jumper wire to get a reading across both pins at the same time right?
     

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