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First post, by RetroNoob

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Should I bother looking for a replacement screen for my MT-32 (Old)?

The photo is a bit over bright for what I actually seen in person. It's readable, but there is a strong glow around the info, not just the info glowing, like I see in photos online.

As far as I know there's no contrast/brightness settings for the MT-32.

From other photos I've seen on the internet, it shouldn't glow as much as this?

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Last edited by RetroNoob on 2019-06-20, 09:42. Edited 1 time in total.

Reply 1 of 17, by keropi

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something is definitely wrong - maybe some simple component like a resistor is burned and the screen gets too much voltage or something... did you open the unit? maybe some component looks bad?

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Reply 2 of 17, by RetroNoob

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No, I haven't opened it up yet. I didn't really want to, unless there was something wrong.

I guess I'd better now.

I don't suppose you know where to get a replacement display from, that doesn't cost an arm and a leg?

Reply 3 of 17, by keropi

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there is a project to replace the original lcd screen with a modern one: http://sensi.org/~tnt23/sed1200emu/index.html
other than that I don't know any other sources...

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Reply 4 of 17, by Spikey

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Is the sound still working correctly? I've had weird contrasts on the LCD when I had an unsuitable power supply attached, or when I had a correct power supply with the polarity reversed.

Reply 5 of 17, by Jo22

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The power supply question is a good one. If the PSU is a cheap "modern" switching type from the local electronics store or super market, then I'm not surprised. 😉

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Reply 6 of 17, by Spikey

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I have legitimately thought the same thing as the OP, only to listen and the sound was messed up. I have moved back and forth between the US and Australia several times, having moments where I have repurposed household adapters to use for an evening, some times working fine, some not so well 😀

Reply 7 of 17, by RetroNoob

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keropi wrote:

there is a project to replace the original lcd screen with a modern one: http://sensi.org/~tnt23/sed1200emu/index.html
other than that I don't know any other sources...

Thanks, I guess I might have to learn more about that.

Spikey wrote:

Is the sound still working correctly? I've had weird contrasts on the LCD when I had an unsuitable power supply attached, or when I had a correct power supply with the polarity reversed.

Yes, the sound works fine. The polarity is fine - negative centre.

Jo22 wrote:

The power supply question is a good one. If the PSU is a cheap "modern" switching type from the local electronics store or super market, then I'm not surprised. 😉

I guess the PSU is one of type you mention, but I've the same problem with the original Roland PSU with a 240V > 100V.

Spikey wrote:

I have legitimately thought the same thing as the OP, only to listen and the sound was messed up. I have moved back and forth between the US and Australia several times, having moments where I have repurposed household adapters to use for an evening, some times working fine, some not so well 😀

Without swapping all the caps, I feel it's just the screen has started for fail. I've now come across other screens on other people's MT-32, that look as if they're getting to the same stage as mine is.

Reply 12 of 17, by RetroNoob

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Sorry for getting this going again after so long.

I never did get a replacement screen, because it turned out, it didn't match up anyways.

I have recently managed to get a REAL Roland ACB-240 No.12449564 PSU, that is the spec that the MT-32 needs., and works here in the UK.

The screen still has the same problem. So it's nothing to do with the PSU.

I guess I'm going to have to look into figuring out what the Cap replacement needs are.

Reply 13 of 17, by detalite

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I think that resistor responsible for contract is R44 27k (may vary betwen versions). It is connected between ground and pin V_LCD. I suggest to replace it with 50k potentiometer.
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Reply 14 of 17, by Salient

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I just unboxed my second, virtually unused, MT-32 I still had at the attic to check this out and guess what, it also has the bright-glow-phenomenon, with all PSU's i checked.
My other, somewhat beat-up and (ab)used all the time and modified with a crude self-built built-in power supply, is just fine. 😀
Sound is ok on both machines though.

I'm going to look into that resistor but I do feel kind of sorry for the device since it's immaculate still, both inside and outside, so there is a small chance I just leave it like this.

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Reply 15 of 17, by CrossBow777

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It really does surprise me that a modern OLED screen isn't already available for the MT-32. They appear to have OLED replacements for nearly every other major Roland synth that was in use in the 80s - 90s and I would think that the modules were popular enough that there would be a demand for replacements?

I've also wondered if the screens used in the MC-50 and the MT-100 are the same type and if those could be salvaged? In fact, now that I think about it, I think I found someone that made or makes a replacement OLED for the MC-50?

If any component is at fault, it would likely be on the LCD board itself as I believe the driver and pretty much everything is on that LCD board. I think only the data lines and power come from the SIP style ribbon cables?

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Midi Modules: MT-32 (OLD), MT-200, MT-90, SD-20

Reply 16 of 17, by cyclone3d

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CrossBow777 wrote on 2020-06-29, 17:18:

It really does surprise me that a modern OLED screen isn't already available for the MT-32. They appear to have OLED replacements for nearly every other major Roland synth that was in use in the 80s - 90s and I would think that the modules were popular enough that there would be a demand for replacements?

I've also wondered if the screens used in the MC-50 and the MT-100 are the same type and if those could be salvaged? In fact, now that I think about it, I think I found someone that made or makes a replacement OLED for the MC-50?

If any component is at fault, it would likely be on the LCD board itself as I believe the driver and pretty much everything is on that LCD board. I think only the data lines and power come from the SIP style ribbon cables?

Why would you want to take a screen from an MT-100 unless it is dead? The MT-100 is an MT-32 with sequencer.

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Reply 17 of 17, by CrossBow777

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cyclone3d wrote on 2020-06-29, 18:10:
CrossBow777 wrote on 2020-06-29, 17:18:

It really does surprise me that a modern OLED screen isn't already available for the MT-32. They appear to have OLED replacements for nearly every other major Roland synth that was in use in the 80s - 90s and I would think that the modules were popular enough that there would be a demand for replacements?

I've also wondered if the screens used in the MC-50 and the MT-100 are the same type and if those could be salvaged? In fact, now that I think about it, I think I found someone that made or makes a replacement OLED for the MC-50?

If any component is at fault, it would likely be on the LCD board itself as I believe the driver and pretty much everything is on that LCD board. I think only the data lines and power come from the SIP style ribbon cables?

Why would you want to take a screen from an MT-100 unless it is dead? The MT-100 is an MT-32 with sequencer.

Quite right and I should have been more clear. I meant salvaged from otherwise dead units. And I meant it more as a question on if the same screen in the MT-100 is the same used in the MT-32. I assumed they are because as you said, the MT-100 is an MT-32 with built in sequencing. I wasn't suggesting they be pulled from working units.

Also I was wrong about the possiblity of an OLED solution for the MC-50..it was the MC-500 I was thinking of and I still wonder if those screens are the same used in the MT-120 and MT-200?

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Midi Modules: MT-32 (OLD), MT-200, MT-90, SD-20