Roland MC-303 power reset issue

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trevSki
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Roland MC-303 power reset issue

Post by trevSki » Wed Aug 26, 2020 7:33 pm

Hi all...

First post here and I was wondering if anyone could shed a light on a particular issue I'm having with a Roland MC-303 that I acquired recently. I did see an earlier post here on a slightly different issue and there seemed to be a few knowledgeable people on these units so I'm hoping that someone might have seen this issue before.

The problem is that the unit will power up fine but will randomly reset itself once powered up. Doesn't seem to be related to heat or the length of time the unit has been on, or in reaction to any particular button presses or actions on the control surface. The fault happens sometimes when the unit is not even playing a pattern. Display goes to black then resets and powers up as per initial power-up.

I haven't manged to find any reference to this happening anywhere... have tried re-seating all ribbon connectors, checked and re-seated the battery (battery test was ok), checked the power socket and switch (no loose connections there, cannot replicate fault by wobbling the connector). PSU is non standard but correct spec centre negative 9V DC.

Does anyone have any ideas other than maybe replacing the caps in the power supply area and re-flowing the power input contacts? I did notice when looking at the schematics that there is a IC marked as a 'Reset Control' (IC13). Could this chip be faulting and causing the issue or would it more likely be a fault command being sent to this chip that is causing it to reset?

Unfortunately I don't have any spare boards or parts to test with so I thought I'd just put it out there to you guys before I pull the rest of my hair out or consign it to a doorstop.

Any advice would be gratefully received.

Regards
TrevSki
Last edited by trevSki on Thu Aug 27, 2020 10:56 pm, edited 1 time in total.

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meatballfulton
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Re: Roland MC-303 power reset issue

Post by meatballfulton » Wed Aug 26, 2020 7:45 pm

I recall my MC-303 had a pretty high current wall wart, not the usual AC-120. Are you sure your supply is OK?
I listened to Hatfield and the North at Rainbow. They were very wonderful and they made my heart a prisoner.

trevSki
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Re: Roland MC-303 power reset issue

Post by trevSki » Wed Aug 26, 2020 9:38 pm

meatballfulton wrote:
Wed Aug 26, 2020 7:45 pm
I recall my MC-303 had a pretty high current wall wart, not the usual AC-120. Are you sure your supply is OK?
Not entirely, no I bought it untested without a supply and ordered one from eBay with 'apparently" correct specs as the proper replacement one wasn't available. Unfortunately I don't have a meter with me to measure the output across it... maybe I'll just buy the proper power supply to try... it had crossed my mind but thought I'd examine other causes first. Thanks for your input 8-)

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meatballfulton
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Re: Roland MC-303 power reset issue

Post by meatballfulton » Wed Aug 26, 2020 10:54 pm

The spec says the power requirement is 9V, 500mA but the supply Roland shipped it with was 9V, 1A (1000mA).
I listened to Hatfield and the North at Rainbow. They were very wonderful and they made my heart a prisoner.

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Re: Roland MC-303 power reset issue

Post by trevSki » Thu Aug 27, 2020 8:40 am

meatballfulton wrote:
Wed Aug 26, 2020 10:54 pm
The spec says the power requirement is 9V, 500mA but the supply Roland shipped it with was 9V, 1A (1000mA).
Thanks mate....makes you wonder why they didn't change the Spec to 1A really...so much for me carefully checking.... that'll certainly give me a bit more head room over the 500mA. Have ordered the proper Roland PSB-1U for it (probably should have just done that in the first place) and we'll see if that fixes the issue. Thanks for the tip. Fingers crossed it sorts it.

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Re: Roland MC-303 power reset issue

Post by trevSki » Thu Aug 27, 2020 10:55 pm

Update: Bought a brand new PSB-1U for it today and had it on test for a few hours now and it hasn't faulted once, so hopefully thats the issue solved. I did check the aftermarket one after the last post and it was actually rated for 1A not 500mA as I thought, so maybe there's some extra current regulation or something in the proper Boss one, or the other one was just faulty somehow. Should have just bought one at the start really but there ya go. Thanks for the advice @meatballfulton

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