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Roland Cube 30

No function including no LEDs. Failed 3.3V VR, ominously tested no load as 4V, maybe normal , will have to try some known gooders About 1.5 ohm ground to 3.3V rail. Found where the confusing inner 3.3V plane came off (near IC9) cutting either side of there and a couple of other places, limited to one area of board. Powering with V and A limited bench ps set for 3V limit, taking .2A, dropped .4V and .3A dropped .7V. With IR thermometer I would have thought 0.2W would shine out , about 1 degree C only above, around IC4 and AKM 4552VT codec, Japanese datasheet out there. From that I think I know where to cut its supply trace, despite being under the IC. Anyone been here before ?, the main Roland chips are dead cold. Anyone know what 5 pin SC70-5 or SOT416 format IC top coded JAPN is, just in passing, googling got nowhere ? Reminder to myself when using IR thermometer - use a distant LED torch to illuminate the board. Misled into "finding" a faulty main cap , as heating up a few degrees in one area of the cap, despite no normal connection to any 3V line. My flourescent lamp was reflecting heat off the cap top. Even turning off the lamp made no difference , retained heat of course. Also handled a switch and 3 seconds later found a (phantom) hot spot there. No change in ohmage heating or freezing. I don't fancy removing a 16p IC, where it is, even if a replacement was available, but now I've got this far I have to follow it through to the end

Reply to
N_Cook
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The J of 4 letter code JAPN has 2 dots over . My IR thermo has a conical reflector to the pyro, just the right size to test each of the couple of dozen radial electros, by placing end of cap in the cone, and no excess over ambient

Reply to
N_Cook

Isolated that IC and still low ohms load on 3.3V line. About all that was left to cut was area of the big BOSS chippery. Cut line to p38 of 80 pin R02565501 and inside that was the low ohms, so end of the road I think. Perhaps a thin trace 3.3V or ground line runs under the AKM 16 pinner. Perhaps I'll solder a wire to p38 and drive again with some less constrained current and see what happens with IR monitoring, for edification. First Cube Roland main chip failure like this I've come across, 2 stomp boxes before IIRC

Reply to
N_Cook

Applying bench ps to pin 38 isolated from all else, then for .2A, 1.3V dropped and 10 deg C rise of the chip.

Reply to
N_Cook

before consigning to the mule park , investigated the JAPN IC a bit

5 pin, p1&2 gnd, 3 N/C unless hidden in an interlayer,4 to large Boss R03015201 p21, p5 absent, p6 3.3V Power-on reset IC?
Reply to
N_Cook

before consigning to the mule park , investigated the JAPN IC a bit

5 pin, p1&2 gnd, 3 N/C unless hidden in an interlayer,4 to large Boss R03015201 p21, p5 absent, p6 3.3V Power-on reset IC?

The schematic designates the output of this chip to be Reset0, and becomes Reset1 after R19.

Reset0 goes to logic chip IC1, Reset1 goes to CN U2 pin6, CN U2 being designated Not Utilised.

I can't see any direct connections of these reset lines to the main CPU.

Gareth.

Reply to
Gareth Magennis

before consigning to the mule park , investigated the JAPN IC a bit

5 pin, p1&2 gnd, 3 N/C unless hidden in an interlayer,4 to large Boss R03015201 p21, p5 absent, p6 3.3V Power-on reset IC?

The schematic designates the output of this chip to be Reset0, and becomes Reset1 after R19.

Reset0 goes to logic chip IC1, Reset1 goes to CN U2 pin6, CN U2 being designated Not Utilised.

I can't see any direct connections of these reset lines to the main CPU.

Oops, that's bollocks. Reset0 goes to pin 81 on the main CPU. My eyesight is getting worse.

But Reset0 does indeed also go to some logic at IC1, thence into IC2.

Gareth.

Reply to
Gareth Magennis

"Gareth Magennis"

** I needed one of those a few years ago for a Cube 30 Bass.

Roland Australia could not supply, saying it was obsolete.

So, I picked a similar part ( 3 pin SMD reset IC ) from the Farnell Cat and used that.

The pin out was different, so I had to mount it up side down.

.... Phil

Reply to
Phil Allison

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