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Roland GR-30 Guitar Synth cap replacement

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  • #16
    It's SOUL-der over here.

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    • #17
      So this is one case that your damned silent letters aren't silent..... Is there anything we should know about Whip, Lincoln, or the above mentioned Salmon?

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      • #18
        It's 'sold her' over here 'sod her' over there. When I was in Greece last summer they pronounced the w in swordfish.

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        • #19
          Cambridge Dictionary says:

          https://dictionary.cambridge.org/es/...ukswipe023.mp3
          Juan Manuel Fahey

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          • #20
            Originally posted by J M Fahey View Post
            Oh dear. You shouldn't have showed me that feature, Juan. I can have some fun with that!
            "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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            • #21
              Well, in spite of what Mr. Carlson and his videos would have you believe, Canadian's do not pronounce the L in solder. I have no idea where he got that from, perhaps he came up under a Brit instructor.
              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


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              • #22
                I kind of feel like I’ve caused an international incident here.... Im just going to imagine Dick Van Dyke as a Cockney chimney sweep and say it like that, guv’nas. Anyhoo got my in-circuit tester opened it back up and realized i was thinking of this other thing ive been working on with the surface mounted caps, this has all normal caps. None of them look bad, so I compare the values listed on the service manual,there are only 4 varieties, and check them all using say 1000u/6.3v etc., right.Click image for larger version

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                • #23
                  I don't know what you mean by " ....and check them all using say 1000u/6.3v". Can you clarify?

                  A faulty component can look just the same as a good one, though if you did have an oozing or encrusted cap that wouldn't be good. Did you first check the battery voltage to see if something is running it down? If the battery is getting discharged I'd be looking for a low resistance effectively appearing across the terminals. If the battery voltage is good than you could have a high resistance in series with the battery.

                  A problem you may encounter though is that the battery circuit is fine, but the battery could be mistakenly being reported as faulty.

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                  • #24
                    I don't know what you mean by " ....and check them all using say 1000u/6.3v". Can you clarify?
                    that in this device there are only 4 different caps, so a good reading is going to be one of four values, like the 1000u(F) 6.3v. Im coming to the realization that I should have spent more on my esr meter, and that one of the ones that list good/bad are probably better suited to my ability. The battery does not actually drain, the system just alerts me to a bad battery at startup. The battery is used to hold user patches and preferences, so I guess that there could be a couple different components that have gone bad. Or it might just be an alert that means nothing. Someone told me it was a bad cap, but none of them are obviously damaged, although two of them apparently have a small red line at the top right next to the cap, im not sure if it’s electrolytes or just the way they are designed. Roland cant help me due to a new company policy, and I totally understand that, theres no money in helping a cheapskate like myself avoiding buying something new. Thanks again, regards Chris

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                    • #25
                      Can you post a schematic?

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                      • #26
                        Originally posted by Mick Bailey View Post
                        Can you post a schematic?
                        Heres a link to the service manual with the schematic, http://www.synfo.nl/servicemanuals/R...VICE_NOTES.pdf
                        I’m repairing my computer right now and only have an iPad so the best I can do is screenshots. I hope they’re detailed enough for you. Thanks again, regards ChrisClick image for larger version

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                        • #27
                          Did you go through the internal battery test routine (section 4 page 7). It also gives the place to check if it fails - R86 in series with the battery, and IC20.

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                          • #28
                            Originally posted by Mick Bailey View Post
                            Did you go through the internal battery test routine (section 4 page 7). It also gives the place to check if it fails - R86 in series with the battery, and IC20.
                            Hello Mr Bailey,
                            No and yes, and no. I didn’t do the test, i did replace the battery and checked the resistor, and Im sure about the ic chip. I’d started down that path when I was told it was a cap, is “its a bad cap” the electronics version of “I think it’s the carburetor “?. In testing the chip I would use my regular multumeter with the battery in place and compare the values listed on the schematic, right? And if it is bad, I’m probably up the creek unless I can find a kindly Roland service provider... Well, here’s to hoping that I can figure that the chip is good. Thanks for subtlely reminding me something I should have never forgotten, RTFM!!!

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                            • #29
                              With the synth unpowered (but with the battery in place) make sure you have a voltage greater than 2v on the VCC pin of IC25. This is the memory retention voltage.

                              IC20B is configured as a buffer, so you should see the same voltage on pin 7 as pin 5 if the synth is powered. Trace this through to make sure you get a voltage on the processor side of R87. This is what the processor uses to report low battery voltage. Actually, it's safer to initially check the voltage on either side of R87 rather than risking a probe slip on the IC pins.

                              Does the unit retain its memory after being powered off?

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                              • #30
                                Originally posted by Mick Bailey View Post
                                With the synth unpowered (but with the battery in place) make sure you have a voltage greater than 2v on the VCC pin of IC25. This is the memory retention voltage.

                                IC20B is configured as a buffer, so you should see the same voltage on pin 7 as pin 5 if the synth is powered. Trace this through to make sure you get a voltage on the processor side of R87. This is what the processor uses to report low battery voltage. Actually, it's safer to initially check the voltage on either side of R87 rather than risking a probe slip on the IC pins.

                                Does the unit retain its memory after being powered off?
                                greater than 2v on the VCC pin of IC25
                                Do you mean the ic20? I'm having a hard time seeing any voltages on the pins of the ic20.

                                Does the unit retain its memory after being powered off?
                                A resounding yes. I mean, that's a good thing, right? If it says that there is a battery problem, but the function that the battery maintains is still working, might this be one of those If it aint broke, don't fix it realities....

                                Also I guess you can't see it here but there is a small amount of red residue on the silver of this cap. I can't see that its part of the backup, but I'm not that good at reading schematics either. Thanks again, regards ChrisClick image for larger version

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