SX-880 restoration project

Discussion in 'Pioneer Audio' started by DerekR, Jun 15, 2017.

  1. DerekR

    DerekR New Member

    Messages:
    47
    After having fun/frustration getting an SX-650 up and running, decided I needed another project. Found an SX-880 on ebay for cheap that 'used to run' but had the power cable cut off. Seemed like it could become a fun project. I'm sure I'll need some help with troubleshooting and diagnosis.


    Here's night 1:

    Soldered the power cable back together, pulled the fuses. All ohmed out good, replaced the 5A main fuse and plugged it in. Solid readings on the 1A and 2A fuses. Replaced the burned out dial lamps, and inserted the 2A fuse. Flip power again and lamps come on! yay!

    Insert 1A fuses, turn on, no function indicators. No tuning meter movement. No relay clicks. Tap gnd to the relay coil briefly and it clicks on.

    So poked around for a while and did some AK searching. Seems the power transistors are finicky on the SX-880s. So at suggestion here: http://www.audiokarma.org/forums/index.php?threads/silent-pioneer-sx-880.316145/, I pulled the solder off the power transistors and resoldered.

    Q26 has 63V on the collector, 14.5V on the base, and .... -0.2V on the emitter. Should be 13.5V, which supplies power to the PA3004 protection IC (explains no relay), to the tuner board (no meter movement), and to the led function indicators (no leds).

    Pulled Q26 for some diode checks. Good collector-base tests at around 0.56V, but base-emitter junction is no-go.

    Path forward:
    Looks like I need to put together a parts order. Perusing around AK shows this to be an equivalent: http://www.mouser.com/ProductDetail/ON-Semiconductor/MJE15032G/?qs=HVbQlW5zcXUS0E66TrcxZw==

    I'd like to get the receiver powered up and responsive before I go spend $60 on recap supplies... anything else I should buy in the first parts order? I'm thinking probably a larger heatsink for Q26, suggestions?
     
    Last edited: Jun 15, 2017
  2. DerekR

    DerekR New Member

    Messages:
    47
    I found two KSC2690AYS in my parts box from the SX-650 rebuilt (PA2 board Q15). It looks like it's only rated for 20W instead of the MJE15032's 50W. Worth dropping in to see if it comes up or will it damage immediately?
     
  3. DerekR

    DerekR New Member

    Messages:
    47
    Turns out I'm super impatient. Installed it. Unit powers up, Indicators on! Tuner even tunes to a station without an antenna and locks into stereo... and best yet... PROTECTION RELAY KICKS IN! The little KSC gets pretty hot though, definitely not going to let it stay on for very long

    Q26:
    E 13.78V
    C 35.2V (I may have mis-measured this in the first post....)
    B 14.4V


    I think this might just become a fun project
     
    Last edited: Jun 15, 2017
  4. markthefixer

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

    Messages:
    20,627
    Location:
    Bensenville,Illinois
    :yikes: HEAT SINK IT!!!!! 1 watt dissipation bare!!! :yikes:

    power supply could oscillate - original was 8 mhz, mje's are 30mhz and 2690 is 155mhz
     
    Last edited: Jun 15, 2017
  5. DerekR

    DerekR New Member

    Messages:
    47
    Gooooood, I was hoping you'd chime in. The KSC was just for power up to see if Q26 might have been a root cause. Going to order some MJEs tomorrow unless you have a better suggestion. Do you have a recommended heatsink upgrade that you know fits?
     
  6. markthefixer

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

    Messages:
    20,627
    Location:
    Bensenville,Illinois
    no part numbers. nor does my comment signal assent. :rolleyes:
     
  7. fernarias

    fernarias AK Subscriber Subscriber

    Messages:
    829
    Location:
    Merced, CA
    I have the 880 and the 890 that have been recapped. Both also have the same heat damage and I was thinking of mounting the to-220 on the heatsink for the power amp transistors (isolated of course). One drilled hole per transistor and braided wire. I haven't done it yet but that's my solution.

    I am also going to replace the old sip op amps.
     
  8. DerekR

    DerekR New Member

    Messages:
    47
    Did some forum scouring today, and bought a whole load of caps and transistors from mouser. As an after thought I bought some various heatsinks to see if I can find some larger ones that will fit or something that might be able to bolt onto the existing heatsinks to expand the surface area a bit.

    Will post parts lists and results after they get installed
     
  9. john stumpf

    john stumpf AK Subscriber Subscriber

    Messages:
    390
    Location:
    philippines
    i made heat sinks from sheet aluminum. you dont need thick stuff.015" will do its AREA NOT MASS that gets the job done. if you buy the isolating mounting kits from mouser the heat sink wont be energized.its hot here so on all my sets i use a boxer fan on the top on a piece of leatherette that covers the upper grille area. in the center i cut a hole for the diameter of the fan. air flow is from the bottom up to take advantage of convection not fight it.
     
  10. DerekR

    DerekR New Member

    Messages:
    47
    List of transistor details and replacements for posterity, not necessarily replacing:
    - most replacements were specified by markthefixer
    - transistor parameters gathered from datasheets

    ORIGINAL: Board Ref PN Type package pinout voltage Collector Current wattage fT hfe
    REPLACEMENT: Mouser package pinout voltage Collector Current wattage fT hfe


    main board Q11 2SC1904 NPN TO-126 ecb 150V 0.05A 1W 70MHz 35-500
    512-KSC3503DSTU TO-126 ecb 300V 0.1A 7W 150MHz 60-120

    main board Q12 2SC1904 NPN TO-126 ecb 150V 0.05A 1W 70Mhz 35-500
    512-KSC3503DSTU TO-126 ecb 300V 0.1A 7W 150MHz 60-120

    main board Q13 2SC1775A NPN TO-92 ecb 120V 0.05A 0.3W 200MHz 400-1200
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q14 2SC1775A NPN TO-92 ecb 120V 0.05A 0.3W 200MHz 400-1200
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q15 2SC1913 NPN TO-220 bce 150V 1A 15W 120Mhz 65-330
    512-KSC2073TU TO-220 bce 150V 1.5A 25W 4MHz 40-140

    main board Q16 2SC1913 NPN TO-220 bce 150V 1A 15W 120MHz 65-330
    512-KSC2073TU TO-220 bce 150V 1.5A 25W 4MHz 40-140

    main board Q17 2SA913 PNP TO-220 bce -150V -1A 15W 120Mhz 65-330
    512-KSA940TU TO-220 bce -150V -1.5A 25W 4MHz 40-140

    main board Q18 2SA913 PNP TO-220 bce -150V -1A 15W 120Mhz 65-330
    512-KSA940TU TO-220 bce -150V -1.5A 25W 4MHz 40-140

    main board Q19 2SC1775A NPN TO-92 ecb 120V 0.05A 0.3W 200MHz 400-1200
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q20 2SC1775A NPN TO-92 ecb 120V 0.05A 0.3W 200MHz 400-1200
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q21 leave alone, robust part

    main board Q22 leave alone, robust part

    main board Q23 2SC945 NPN TO-92 ecb 50V 0.1A 0.25W 250Mhz 90-270
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q24 leave alone, robust part

    main board Q25 leave alone, robust part

    main board Q26 2SD712 NPN TO-220 bce 100V 4A 30W 8MHz 55-300
    512-KSC2073TU TO-220 bce 150V 1.5A 25W 4MHz 40-140

    main board Q27 2SB536 PNP TO-220C bce -120V -1.5A 20W 40MHz 40-250
    512-KSA940TU TO-220 bce -150V -1.5A 25W 4MHz 40-140

    main board Q28 2SC945 NPN TO-92 ecb 50V 0.1A 0.25W 250Mhz 90-270
    512-KSC1845FTA TO-92 ecb 120V 0.05A 0.5W 110MHz 200-1200

    main board Q29 2SA904 PNP TO-92 bce -90V -0.05A 0.2W 150MHz 250-1200
    512-KSA1013YTA TO-92L ecb -160V -1A 0.9W 50MHz 60-320

    main board Q30 2SD325 NPN TO-220C bce 35V 1.5A 10W 8MHz 40-320
    512-KSC2073TU TO-220 bce 150V 1.5A 25W 4MHz 40-140

    main board Q31 2SC1384 NPN TO-92 ecb 50V 1.5A 1W 200MHz 85-340
    512-KSC2690AYS TO-126 ecb 120V 1.2A 20W 155MHz 60-320

    main board Q32 2SA850 PNP TO-92 bce -100V -0.5A 0.8W 130MHz 55-300
    512-KSA1013YTA TO-92L ecb -160V -1A 0.9W 50MHz 60-320

    main board Q33 2SA904 PNP TO-92 bce -90V -0.05A 0.2W 150MHz 250-1200
    512-KSA1013YTA TO-92L ecb -160V -1A 0.9W 50MHz 60-320

    main board Q34 2SA904 PNP TO-92 bce -90V -0.05A 0.2W 150MHz 250-1200
    512-KSA1013YTA TO-92L ecb -160V -1A 0.9W 50MHz 60-320

    main board Q36 2SC1914 NPN TO-92 bce 90V 0.05A 0.2W 150MHz 250
    512-KSC2383YTA TO-92L ecb 160A 1A 0.9W 100MHz 60-320

    main board Q37 2SC1885 NPN TO-92 ecb 150V 0.1A 0.75W 200MHz 150
    512-KSC2690AYS TO-126 ecb 120V 1.2A 20W 155MHz 60-320
     
  11. DerekR

    DerekR New Member

    Messages:
    47
    Working list of caps and part numbers

    *Bolds below are updated to list after performing recap
    Board Ref Desig Capacitance Voltage Family Replacement RepC RepV

    main board c101 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c102 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c105 470 6 cea 647-UKW1V471MPD 470 35
    main board c106 470 6 cea 647-UKW1V471MPD 470 35
    main board c115 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c116 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c119 100 25 cea 647-UKW1E101MED 100 25
    main board c120 100 25 cea 647-UKW1E101MED 100 25
    main board c205 1 50 ceanl 647-UKL1H010KDDANA 1 50
    main board c206 1 50 ceanl 647-UKL1H010KDDANA 1 50
    *main board c209 470->47 6.3 cea 647-UKW1V471MPD->647-UKW1V470MDD 470->47 35
    *main board c210 470->47 6.3 cea 647-UKW1V471MPD->647-UKW1V470MDD 470->47 35
    main board c215 100 25 cea 647-UKW1E101MED 100 25
    main board c216 100 25 cea 647-UKW1E101MED 100 25
    main board c217 4.7 25 ceanl 647-UKL1H4R7KDDANA 4.7 50
    main board c218 4.7 25 ceanl 647-UKL1H4R7KDDANA 4.7 50
    main board c227 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c228 2.2 50 ceanl 647-UKL1H2R2KDDANA 2.2 50
    main board c229 0.22 50 ceanl 667-ECQ-E2224KF 0.22 250
    main board c230 0.22 50 ceanl 667-ECQ-E2224KF 0.22 250
    *main board c301 100->10 16 cea 647-UKW1E101MED->647-UKW1H100MDD 100->10 25->50
    main board c302 0.47 50 cea 647-UPM1HR47MDD 0.47 50
    main board c303 0.47 50 cea 647-UPM1HR47MDD 0.47 50
    main board c304 0.47 50 cea 647-UPM1HR47MDD 0.47 50
    main board c305 0.47 50 cea 647-UPM1HR47MDD 0.47 50
    main board c401 10 50 cea 647-UKW1H100MDD 10 50 (did not find on board)
    main board c402 220 16 cea 647-UKW1C221MED 220 16
    main board c407 470 63 cea 647-UKW1J471MHD 470 63
    main board c408 330 80 cea 647-UKW2A331MHD 330 100
    main board c409 100 50 cea 647-UKW1H101MPD 100 50
    *main board c410 100->220 16 cea 647-UKW1E101MED->647-UKW1C221MED 100->220 25->16
    main board c413 3.3 50 cea 647-UKW1H3R3MDD 3.3 50
    main board c414 3.3 50 cea 647-UKW1H3R3MDD 3.3 50
    main board c415 0.22 35 ceanl 667-ECQ-E2224KF 0.22 250
    main board c416 0.22 35 ceanl 667-ECQ-E2224KF 0.22 250
    main board c417 33 16 cea 647-UKW1V330MDD 33 16
    main board c418 47 16 cea 647-UKW1V470MDD 47 35
    main board c419 10 16 cea 647-UKW1H100MDD 10 16->50
    main board c420 47 35 cea 647-UKW1V470MDD 47 35
    main board c421 47 35 cea 647-UKW1V470MDD 47 35
    main board c422 100 50 cea 647-UKW1H101MPD 100 50
    main board c423 100 50 cea 647-UKW1H101MPD 100 50

    meter c501 4.7 35 cea 647-UKW1H4R7MDD 4.7 50
    meter c502 4.7 35 cea 647-UKW1H4R7MDD 4.7 50
    meter c503 4.7 35 cea 647-UKW1H4R7MDD 4.7 50
    meter c504 4.7 35 cea 647-UKW1H4R7MDD 4.7 50

    Tuner c27 2.2 50 cea 647-UKL1H2R2KDDANA 2.2 50
    Tuner c28 4.7 35 cea 647-UKW1H4R7MDD 4.7 50
    Tuner c34 1 50 cea 647-UKL1H010KDDANA 1 50
    Tuner c35 22 16 cea 647-UKW1H220MDD 22 16
    Tuner c37 6.8 6 csza 647-UKL1E6R8MDD 6.8 25
    Tuner c38 1 50 ceanl 647-UKL1H010KDDANA 1 50
    Tuner c40 1 50 ceanl 647-UKL1H010KDDANA 1 50
    Tuner c41 1 50 cea 647-UKL1H010KDDANA 1 50
    Tuner c43 330->220 16 cea 647-UKW1C331MPD->647-UKW1C221MED 330->220 16
    Tuner c44 220 16 cea 647-UKW1C221MED 220 16
    Tuner c53 220 16 cea 647-UKW1C221MED 220 16
    Tuner c60 4.7 35 cea 647-UKW1H4R7MDD 4.7 50
    Tuner c61 3.3 50 cea 647-UKW1H3R3MDD 3.3 50
    Tuner c67 22 16 cea 647-UKW1H220MDD 22 50 (did not find on board)
    Tuner c71 10 16 cea 647-UKW1H100MDD 10 50
    Tuner c72 10 16 cea 647-UKW1H100MDD 10 50
    Tuner c76 10 16 cea 647-UKW1H100MDD 10 50 (did not find on board)
     
    Last edited: Jun 19, 2017
  12. DerekR

    DerekR New Member

    Messages:
    47
    My mouser order info.... ordered way more than I needed but I always prefer spares on-hand vs wanting some to finish the job.
    Also price breaks at 10 usually drove down the price so the difference wasn't worth NOT getting more.

    Included some heatsinks for test fitting (almost all of them will be too big I realized when I got home from work).

    OrderQty Price Ext. ManfPN Mouser# Desc
    20 $0.05 $1.06 1N4148 512-1N4148 Diodes - General Purpose, Power, Switching Diodes - General Purpose, Power, Switching 100V Io/200mA BULK
    10 $0.11 $1.10 1N5244B 512-1N5244B Zener Diodes Zener Diodes 14V 0.5W Zener
    10 $0.32 $3.22 KSA1013YTA 512-KSA1013YTA Bipolar Transistors - BJT Bipolar Transistors - BJT PNP Epitaxial Transistor
    5 $0.62 $3.10 KSA940TU 512-KSA940TU Bipolar Transistors - BJT Bipolar Transistors - BJT PNP Epitaxial Sil
    10 $0.15 $1.47 KSC1845FTA 512-KSC1845FTA Bipolar Transistors - BJT Bipolar Transistors - BJT NPN Epitaxial Sil
    5 $0.61 $3.05 KSC2073TU 512-KSC2073TU Bipolar Transistors - BJT Bipolar Transistors - BJT NPN Epitaxial Sil
    10 $0.29 $2.92 KSC2383YTA 512-KSC2383YTA Bipolar Transistors - BJT Bipolar Transistors - BJT NPN Epitaxial Transistor
    10 $0.38 $3.84 KSC2690AYS 512-KSC2690AYS Bipolar Transistors - BJT Bipolar Transistors - BJT NPN Epitaxial Sil
    10 $0.16 $1.57 7721-7PPSG 532-7721-7PPS Thermal Interface Products Thermal Interface Products INSUL SHOULDER WASHR TO-220
    20 $0.07 $1.40 4672 534-4672 Mounting Hardware Mounting Hardware MICA INSUL TO-220
    10 $0.22 $2.22 274-3AB 567-274-3AB Heat Sinks Heat Sinks LOW HEIGHT WAVESOLD .52X.75" NO TAB
    5 $1.40 $7.00 E2A-T220-25E 588-E2A-T220-25E Heat Sinks Heat Sinks Black Anodized Heatsink for TO-220
    2 $1.88 $3.76 RA-T2X-25E 588-RA-T2X-25E Heat Sinks Heat Sinks HTSNK TO-220 218 247 BLK ANODIZED
    2 $2.29 $4.58 RA-T2X-38E 588-RA-T2X-38E Heat Sinks Heat Sinks HTSNK TO-220 218 247 BLK ANODIZED
    2 $2.73 $5.46 RA-T2X-51E 588-RA-T2X-51E Heat Sinks Heat Sinks HTSNK TO-220 218 247 BLK ANODIZED

    Needed* OrderQty Price Ext. ManfPN Mouser# Desc
    1 10 $0.10 $1.00 UKL1E6R8MDD 647-UKL1E6R8MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 6.8UF 25V 20% 85c
    6 10 $0.17 $1.67 UKL1H010KDDANA 647-UKL1H010KDDANA Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 1uF 50 Volt 105C 10% 2mm LS
    7 10 $0.17 $1.74 UKL1H2R2KDDANA 647-UKL1H2R2KDDANA Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50 Volt 2.2uF
    2 10 $0.20 $1.97 UKL1H4R7KDDANA 647-UKL1H4R7KDDANA Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50 Volt 4.7uF 105C
    3 10 $0.20 $1.97 UKW1C221MED 647-UKW1C221MED Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 16volts 220uF 20%
    1 5 $0.48 $2.40 UKW1C331MPD 647-UKW1C331MPD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 16volts 330uF 20%
    6 12 $0.20 $2.36 UKW1E101MED 647-UKW1E101MED Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 25volts 100uF 20%
    5 10 $0.16 $1.58 UKW1H100MDD 647-UKW1H100MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 10uF 20%
    3 10 $0.26 $2.57 UKW1H101MPD 647-UKW1H101MPD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 100uF 20%
    2 10 $0.16 $1.64 UKW1H220MDD 647-UKW1H220MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 22uF 20%
    3 10 $0.12 $1.15 UKW1H3R3MDD 647-UKW1H3R3MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 3.3uF 20%
    6 10 $0.12 $1.15 UKW1H4R7MDD 647-UKW1H4R7MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 4.7uF Radial
    2 3 $0.98 $2.94 UKW1J471MHD 647-UKW1J471MHD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 63volts 470uF 20%
    4 20 $0.16 $3.28 UKW1V330MDD 647-UKW1V330MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 35volts 33uF 20%
    3 10 $0.16 $1.64 UKW1V470MDD 647-UKW1V470MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 35volts 47uF 20%
    4 10 $0.45 $4.51 UKW1V471MPD 647-UKW1V471MPD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 35volts 470uF 20%
    1 3 $1.34 $4.02 UKW2A331MHD 647-UKW2A331MHD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 100volts 330uF Radial
    4 10 $0.12 $1.15 UPM1HR47MDD 647-UPM1HR47MDD Aluminum Electrolytic Capacitors - Leaded Aluminum Electrolytic Capacitors - Leaded 50volts 0.47uF 5x11 20% 2LS
    1 2 $6.69 $13.38 EKMH630VSN153MA63T 661-EKMH630N153MA63T Aluminum Electrolytic Capacitors - Snap In Aluminum Electrolytic Capacitors - Snap In 15000uF 63 Volt
    4 10 $0.23 $2.31 ECQ-E2224KF 667-ECQ-E2224KF Film Capacitors Film Capacitors 250VDC 0.22uF 10% MPET L/S=10mm

    *My notes are a mess, so the needed numbers probably aren't right. Take with a grain of salt.
     
    Last edited: Jun 17, 2017
  13. DerekR

    DerekR New Member

    Messages:
    47
    Tuner knob came nearly seized, same with the balance knob.

    Today's tasks:
    - Deoxit and lube the pots.
    - Deoxit the switches
    - Lubricate the tuner pulleys & tuner knob bearing/flywheel

    Everything spins cleanly now, it's night and day.
    Tuner COULD use some additional cleaning, but would require disassembly of the flywheel and restringing the system is probably the thing I want to do the least.

    Parts don't come in until Wednesday next week, so I think I'm pretty much stalled waiting for a new Q26. I did pick up a couple Realistic Minimus-7W 8ohm monitors on Craigslist today to use as benchtop test speakers for $20. Want to get the unit up and running before I start repairing and veneering the cabinet.
     
  14. DerekR

    DerekR New Member

    Messages:
    47
    Caps and transistors came in today. The three RA-T2X-xxE heatsinks came in and all three are far too large to fit on the board without interference.

    Tonight's tasks:
    - Replaced Q26 and she powers up! Tunes in strong, meters work, sounds good
    - Recapped Meter board and main board 100%.... except I can't find C401 on the board or the schematic! Help?!

    Probably going to be a couple days for the other order of heatsink parts to come in for some trial and error fitting.

    Still need to recap the Tuner board, adjust the DC bias, and swap out the main caps, then on to restoring the cabinet.
     
  15. DerekR

    DerekR New Member

    Messages:
    47
    Recapped the tuner board. I either forgot to mark off caps from the list or I wasn't able to find C67 & C72 due to low resolution on the pcb layout. Updating cap lists with changes I found while working.
     
  16. DerekR

    DerekR New Member

    Messages:
    47
    Deoxit'd the rear RCA plugs and Aux input is clean and clear and functions great, but on the phono input, the left channel pops every few seconds. Is that a bad HA1457 opamp?
     
    Last edited: Jun 20, 2017
  17. DerekR

    DerekR New Member

    Messages:
    47
    Replacement for protection relay ASR-020: Omron MY4-02-DC48. Mouser PN 653-MY4-02-DC48
     
  18. DerekR

    DerekR New Member

    Messages:
    47
    This evening:
    - Replaced main caps, went in well. New main caps were smaller, so used some handlebar foam I had in the garage to fill the space and snug them up
    - Zeroed out the DC bias and set idle current. Noticed last night that the power amp transistors' heatsink was hot to the touch, then when i turned off the unit, the right speaker puffed; told me I had a dc bias issue. She's cooled WAY down.
    - Started peeling vinyl off of the cabinet so I can putty, sand, and veneer.
    - Ordered a new replacement relay, will install later this week if it's in.
    - Set the meters. Don't have a function generator, but do have a cell phone and the app store! Found a freq generator app, set to 1kHz and measured around 1.38VAC,rms (vs 1.5V in service manual. Used DMM to set volume to read 21.9V, adjusted meter pots.

    To do:
    - Install new relay
    - Modify or change heatsinks on Q26, Q27, & Q30
    - Decide if I want to change out any other transistors on the board. Considering swapping out power supply transistors and protection circuit transistors for new KSC/KSAs. Any advice on if I should? If so, which ones are worthwhile?
    - Repair cabinet
    - Long term goal: Get tuner adjusted. I'm considering trying to pick up a Sencore SG165 on fleabay, and would motivate me to finally buy a Rigol 1054Z scope.







     
  19. fernarias

    fernarias AK Subscriber Subscriber

    Messages:
    829
    Location:
    Merced, CA
    Good progress on the 880. The Rigol is nice, that's what I purchased. The Sencore is getting expensive just like the ST 1000A. There are other (sometimes better sometimes good enough) signal generators with RF for less. Look at Knight, Heathkit,Simpson, Eico, etc. Those Panasonic and Kenwood more modern SG are pretty nice. I myself was able to find a Leader for a good price. There are also good videos on alignments now like from this content creator: https://www.youtube.com/channel/UChTN8got77QeKPFRmTJ0teg
     
  20. DerekR

    DerekR New Member

    Messages:
    47
    I've watched his videos a couple of times!

    Did you do the software hack/unlock on your Rigol?

    If I was getting an RF signal gen, I was hoping for the MPX capability so I could tune the stereo decoder as well.
     

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