Roland KR-370 Main board

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • piernov
    Super Moderator
    • Jan 2016
    • 4435
    • France
    #1

    Roland KR-370 Main board

    Just finished refreshing this board. I had to replace all the SMD electrolytic caps, they were all bad and leaked on the board, so also had a lot of work restoring destroyed pads/vias/traces. Not even sure if it works in the end as I got only the board so I can't test it.

    I replaced the 4x 6V 100uF caps by some solid polymer 16V 100uF, and the 13x 16V 10uF by some 10uF 1206 MLCC. The 2x 50V 1uF were replaced by some garbage through hole with the same ratings, I don't think it'll matter that much. The cap at C44 looked like it was ripped off, no idea what it was so left it off, I don't think it matters either.

    Anyway, since there doesn't seem to be any info on the web about this, I'm uploading pictures after the work and also the dump from the socketed EPROM (I removed it to clean the board so I thought why not dump it, if ever someone needs it they would be very happy to find it here…).

    HN27C4096AG-12_KR-370_70781789.BIN.zip
    Attached Files
    Last edited by piernov; 12-07-2023, 03:27 PM.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView
    Tags: None
    • Xan03
      Senior Member
      • Jan 2021
      • 52
      • Europe
      #2
      Re: Roland KR-370 Main board

      These capacitors are absolutely notorious for destroying mid-90s Roland gear. Not that it matters much now but I can't help but wonder which manufacturer was responsible for this and if it's related to the quaternary ammonium salt formulas mentioned on this forum.

      There's a site that claims to have the service manual for this device but as they only seem to send it out in exchange for other service manuals I won't bother linking it here.

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France
          #3
          Re: Roland KR-370 Main board

          Follow-up on this one: it didn't work. Turned on fine, but no audio output at all.
          The owner tested the amp board by plugging in an external source and it was working, so the issue was most likely related to the digital control board that I worked on. They brought me the whole thing so that I could troubleshoot it (now I can't watch TV anymore but no big deal since I never turn it on anyway).

          Probed some stuff with the oscilloscope, basically the audio processor was generating the digital signal that goes into the DAC (NEC UPD63200), but there was nothing on the output of the DAC.
          I couldn't really find something wrong around it, although I kinda suspected the opamp (NEC µPC4570) might be a problem as well. There was a good amount of damage from the leaky capacitors in this area.
          So I went ahead and replaced both chips, and that indeed fixed the problem.

          Now everything seems to be working fine.
          https://youtu.be/sGoPKpv19sA
          Attached Files
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

            Previous template Next

            Related Topics

            Collapse
            • Dani_2024
              Sceptre U550CV-UMR 4K LED, Bad Caps on Main Power Board?
              by Dani_2024
              Hi and thanks in advance for any input you might provide!
              I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
              Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO

              Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this...
              5 Photos
              10-28-2024, 05:06 PM
            • ygorsan
              LG 55NANO77SRA TV – Menu scrolling by itself even after removing button board (Main Board EBU66792103)
              by ygorsan
              Hi everyone,




              I’m looking for help with a persistent issue on an LG TV model 55NANO77SRA, which uses the main board EBU66792103 (also used in LG UQ80 and NANO75/NANO80 series).







              🧩 Problem Summary:
              • The TV keeps scrolling through the menu or selecting items by itself.
              • I removed the physical button board (the entire panel with power and volume buttons) and also disconnected the flat cable (CN202) from the main board.
              • The remote control is not in use (batteries removed), and the TV still shows the same behavior.
              • I
              ...
              07-28-2025, 08:34 AM
            • jb_Bak
              Sony xbr-65x900c main board issues?
              by jb_Bak
              Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

              Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
              Power Board Connector that goes to Main board
              CN6401
              Pin 01 NC
              Pin 02 NC
              Pin 03 "BL_ON": 0V
              Pin 04 "N/C"
              Pin 05 "STBY 3.3V": 3.5V
              Pin 06 "GND": N/C
              Pin 07 "AC_OFF"...
              09-27-2021, 04:52 PM
            • m1ch43lzm
              HP Pavilion 15-eh Board DAG7HAMB8F0 - CPU throttling to 0.4GHz (PROCHOT_EXT) and black screen
              by m1ch43lzm
              Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
              Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic...
              05-12-2025, 08:37 PM
            • cheeky2
              Is it possible to upgrade from a Vestel 17MB97 main board to a 17MB110 Main board?
              by cheeky2
              I suppose the real question is whether the existing pinouts from ether a 17IPS71 psu are cross compatible with a 17IPS12 psu? If they are then the exchange of the main boards should have no issues providing the screen is compatible with both main boards. Obviously you can change the screen configurations easily enough (providing you have the correct files) for the main board. Why may you ask would I do this? Well a lot of the smart features are no longer working on a Hitachi 48HBT62U main board I wish to give it a new lease of life!
              Obviously the same LVDS connector for the screen connection...
              05-25-2024, 03:27 AM
            • Loading...
            • No more items.
            Working...