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DENON AVR-788 RED LIGHT OF DEATH — Parallax Forums

DENON AVR-788 RED LIGHT OF DEATH

Buckostuco1964Buckostuco1964 Posts: 1
in General Discussion
Have the red light of death on my Denon AV 788 Surround sound receiver.
Went to Youtube and saw a number of people who had success by changing out the Power Supply Board Linear Voltage Regulators.
I purchased 4 new regulators from Mouser Electronics; each were the correct part numbers.
I did a bench check of the old regulators and found that the old 7508A was at 605 & 1601 in diode mode, so I figured that was the bad regulator.
The new regulator read 619 & 676 (Connecting the positive to the center terminal & negative at each end). After replacing the new part, I still got the Red Light of Death. I plan on changing out the other three regulators just to see if it may solve the problem. Short of mailing the unit out to a shop, is there any advice on what could be the culprit?

Thanks for any constructive input!

Bucko

Comments

  • Duane DegnDuane Degn Posts: 10,588
    I thought the usual coarse of action, when repairing electronics more than a few years old, is to replace electrolytic capacitors?

    I think bad caps is a common problem with audio equipment.
  • ercoerco Posts: 20,256
    Could be caps or anything these days, hard to say. One site estimated over $100 to repair. Doesn't make sense when you can buy a used working unit for $70: http://www.ebay.com/itm/Denon-AVR-788-7-1-Channel-120W-Receiver-Great-Condition-/252814706632

    In fact, just having a working unit on the bench next to yours can help you troubleshoot your problem and zero in on a fix. Compare readings to localize the fault, fix yours, then keep or sell the second unit.

    My very first electronics repair job many moons ago was fixing a Pioneer SX-550 receiver, one channel was dead. I knew nothing about electronics but I dove in with a multimeter, comparing the good & bad channels to isolate the fault. Swapped out a $1 transistor and that receiver still works well today.
  • idbruceidbruce Posts: 6,197
    erco
    My very first electronics repair job many moons ago was fixing a Pioneer SX-550 receiver, one channel was dead. I knew nothing about electronics but I dove in with a multimeter, comparing the good & bad channels to isolate the fault. Swapped out a $1 transistor and that receiver still works well today.

    Nice story.

    From that day forward, your future was set in stone :)
  • ercoerco Posts: 20,256
    idbruce wrote: »
    From that day forward, your future was set in stone :)

    I love the smell of solder in the morning. Bacon is a close second.
  • MikeDYurMikeDYur Posts: 2,176
    edited 2017-03-29 14:19
    erco wrote: »
    Could be caps or anything these days, hard to say. One site estimated over $100 to repair. Doesn't make sense when you can buy a used working unit for $70: http://www.ebay.com/itm/Denon-AVR-788-7-1-Channel-120W-Receiver-Great-Condition-/252814706632

    In fact, just having a working unit on the bench next to yours can help you troubleshoot your problem and zero in on a fix. Compare readings to localize the fault, fix yours, then keep or sell the second unit.

    My very first electronics repair job many moons ago was fixing a Pioneer SX-550 receiver, one channel was dead. I knew nothing about electronics but I dove in with a multimeter, comparing the good & bad channels to isolate the fault. Swapped out a $1 transistor and that receiver still works well today.


    I have had a Pioneer SX-850 on a shelf for years, bad channel. Haven't been into audio for a long while because of small animals in the house. Like it loud!

    EDIT: Sorry but I have to take screenshots of my pictures so the size is ok for upload.
    Screenshot_2017-03-29-09-33-42.png
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    Screenshot_2017-03-29-09-34-13.png
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  • PublisonPublison Posts: 12,366
    Still have my SX-1250 from the '70s.

    http://classicreceivers.com/pioneer-sx-1250

    Best combo ever made.
  • MikeDYurMikeDYur Posts: 2,176
    edited 2017-03-29 16:31
    Publison wrote: »
    Still have my SX-1250 from the '70s.

    http://classicreceivers.com/pioneer-sx-1250

    Best combo ever made.



    The 1250 was the monster. Buddy of mine got that one, they sure made the 70s ROCK!. What speakers did you you get for that. I think I bought the biggest they had:

    EDIT: I remember now, they were the smallest in the HPM series that had walnut veneer cabinet. The HPM-60 had some kind of vinyl covered compressed wood, if I remember right.
    Screenshot_2017-03-29-10-53-23.png
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  • ercoerco Posts: 20,256
    I still have several Realistic (Radio Shack) speakers, giant Mach Ones and a smaller pair of MC-somethings. Had to replace all speaker surrounds with new foam ones, still sound good. Let's hear it for ferro-fluid cooled tweeters!
  • PublisonPublison Posts: 12,366
    MikeDYur wrote: »
    Publison wrote: »
    Still have my SX-1250 from the '70s.

    http://classicreceivers.com/pioneer-sx-1250

    Best combo ever made.



    The 1250 was the monster. Buddy of mine got that one, they sure made the 70s ROCK!. What speakers did you you get for that. I think I bought the biggest they had:

    EDIT: I remember now, they were the smallest in the HPM series that had walnut veneer cabinet. The HPM-60 had some kind of vinyl covered compressed wood, if I remember right.
    Back the, Bose 901's were all the rage, so I had to have them. :)

    Then I got some Altec-Lansing Voice of the Theater from the band that I did sound for.

    http://www.audioheritage.org/html/profiles/altec/vott.htm

    The A5X. That Pioneer would drive the heck out of them.

    But we are derailing this thread, although it has nothing to do with Parallax. I may have to sink it.






  • MikeDYurMikeDYur Posts: 2,176
    I think we had this discussion before, but I didn't know how to spell de ja vou.
  • Don MDon M Posts: 1,652
    I have a 1250 along with a pair of HPM-100's
  • MikeDYurMikeDYur Posts: 2,176

    Don M wrote: »
    I have a 1250 along with a pair of HPM-100's

    My grills still look pretty good to, sometimes hard to do, when they're involved in a move or two along the way.


    20170329_142128.jpg
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  • ercoerco Posts: 20,256
    edited 2017-03-29 18:47
    Publison wrote: »
    But we are derailing this thread, although it has nothing to do with Parallax. I may have to sink it.

    Wait, how can I hook up a Propeller to control my audio receiver?

    Phew, that was close!

    Actually I just liked the "red light of death" phrase. Hoped it was lasers on sharks or thereabouts.

  • RickBRickB Posts: 395
    edited 2017-03-30 23:02
    Are you very certain of the part #? I find no credible mention of a 7508 regulator on the web. 7805 is a common p/n and is mentioned in references to Denon products. The center pin in the TO220 pkg is usually grounded in a negative ground power supply.

    Did you actually measure voltages before buying parts?
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2017-04-01 19:51
    erco wrote: »
    I still have several Realistic (Radio Shack) speakers, giant Mach Ones and a smaller pair of MC-somethings. Had to replace all speaker surrounds with new foam ones, still sound good. Let's hear it for ferro-fluid cooled tweeters!

    I have the RS Mach Ones too! Replaced the foam surrounds on the 15" speakers quite a few years ago.
    The cabinets still look new - used a Wipe-On polyurethane.
    Crank them up and they will blow out match...

    I had a Sony receiver that starting giving me fits - the back channels would cut out. Reseated some connectors and it would work for a while then mess up again.
    After some more issues, I junked it and bought a Yamaha RX-V481BL - really pleased with it!
  • ercoerco Posts: 20,256
    Ron Czapala wrote: »
    Crank them up and they will blow out a match...

    Hadn't thought to try that! This VC looks like fun too, whether extinguishing fire or igniting fire rings.



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