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Electronics => Repair => Topic started by: ferrisio on March 07, 2019, 02:42:19 am

Title: Boss DB-90 blown component ID - 'ARVR'
Post by: ferrisio on March 07, 2019, 02:42:19 am
Hi, can anyone help me ID this part please (or even better does anyone have the schematic)?  Is from a Boss DB-90 metronome that someone used the wrong power adaptor with.  It's fairly early on in the power section of the board so I'm guessing it's a voltage regulator or similar.  Seems to be a SOT23-5, the component reference is IC7, and the unit is dead apart from the 2 LEDs above the display lighting.  Since finding this blown IC I haven't troubleshooted much further.  Thanks!
Title: Re: Boss DB-90 blown component ID - 'ARVR'
Post by: fzabkar on March 07, 2019, 04:05:12 am
It might be easier if we could see these components in context. An overall view of the circuit would help.
Title: Re: Boss DB-90 blown component ID - 'ARVR'
Post by: ferrisio on March 07, 2019, 09:56:39 am
Hi, thanks for the reply - you're quite right, some more context would be helpful.  Unfortunately the component in question is on the other side of the PCB so I'll upload both sides.  On the component side pic you can see the +9VDC input via the red/black wires at the very top.  The 2 diodes on the daughterboard that has the DC input jack on seem ok so I'm wondering if it has been over-volted as opposed to reverse-polarity'ed.  Thanks again!

*note ignore the little bit of red insulation on the left hand side of the component side shot - not sure how that got in there!
Title: Re: Boss DB-90 blown component ID - 'ARVR'
Post by: amyk on March 07, 2019, 12:51:48 pm
XC6114E527MR (http://chip.tomsk.ru/chip/chipdoc.nsf/all/EDFB0B9D42E6D2B446257FA6001F4FD1!OpenDocument)
AOZ6115CI (http://chip.tomsk.ru/chip/chipdoc.nsf/all/25694C029F938B6147257BC3007A27E7!OpenDocument)
R1112N251A (http://chip.tomsk.ru/chip/chipdoc.nsf/all/27036BDF6D8366B3C62570F90071388D!OpenDocument)
TC1037CECT (http://chip.tomsk.ru/chip/chipdoc.nsf/all/7CF58A0813BAEB6BC62577FC0035BDF2!OpenDocument)

Trace the schematic and find out what makes most sense.
Title: Re: Boss DB-90 blown component ID - 'ARVR'
Post by: fzabkar on March 07, 2019, 11:37:15 pm
IC7 looks like a buck converter. Q11 would be the MOSFET chopper, probably incorporating a Schottky flywheel diode (FETKY). I can't identify the MOSFET's markings, though.

Edit: Q11 looks like a QS5U27.

QS5U27, Rohm, P-ch MOSFET + Schottky diode, -20V, 1.5A, marking U27, SOT23-5:
http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/mosfet/qs5u27tr-e.pdf (http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/mosfet/qs5u27tr-e.pdf)

Edit #2: There are no feedback resistors, so the converter (PWM controller) appears to be a fixed output type. If we could identify the other ICs, perhaps they would point to a common IC manufacturer?