Circuit diagram zoom

The power jack should have a little diagram that shows the ring and tip. The ring is the long sleeve on the plug, and the center would be the tip. The diagram should show the polarity. It's usually minus to the outer sleeve (ring), and plus to the tip. It might be on the adapter spec plate also. How to tell polarity expected of DC barrel jack
The circuit board should indicate the polarity (plus and ground).

Circuit Diagram - Zoom G1 Service Manual [Page 15]

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  Circuit Diagram - Zoom g9.2tt Service Manual [Page 28]

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Hey, I have seen the same problem in multiples of the Zoom processors; specially those of 505, 505 ii, G1FX, G2 and also, on a Korg (AX9000G) . I somewhere read these gears are designed to decay over time, not sure though.

However, the common symptoms of such issues are Flashing of a dot either at right or left corner, Not remembering which patch/effect it was at before getting turned off and starting over from A1 each time while powered up, Sudden cutting off or dropout of the sound while playing or strumming the guitar or whenever you strike your guitar strings, a sound like buffering comes and restart at once flashing A1, once or twice had shown up 'bt' at display etc. These are all I've heard of.

The reason for this is inappropriate power supply. This mostly happens due to electric voltage bumps and frequent changes of your home amperage and voltage, using inappropriate power supply, providing more current than 350 mili amps or crossing whatsoever ampere limit of your unit and, also, if you are a jerk enough like me who has put one end of the guitar cable at the processor input and that other end of the same cable at the processor output jack and accidentally powered the device on. (That created a chained loop at the audio amplification; eating up a huge amount of current suddenly and burnt the voltage controller of the device at once). My experience says the mosfet ic burns at first and then the resistor is burnt after a few days the mosfet ic dies.

The blinking is mostly for the damage at the internal voltage regulator mosfet ic for which the unit gets unbalanced voltage and tries to explain it by showing up that blinking. There is a 93.76854928 % chance that the resistor carrying the current to the input voltage pin for that voltage controller ic has to be burnt out due to regular and consecutive heating even upto 70 plus degrees for a long period. In most of the cases, the solution should be replacing the voltage controller IC/SMD and also, that burnt resistor right at the start of the circuit board, placed somewhere near the 9v dc jack.

Both the parts are really cheap, both the parts together might cost you around 1 or 2 USD only. Make sure you replace the exact item or the parts equivalent to the replacing dead items. For example, on a zoom 505 ii, the resistor may have been marked as R18 and equivalent to 22 ohms and the voltage regulator ic code is written as

29M33
31*1E

So, make sure to crack the parts' codes properly, if burnt out in case of resistor, check from image or video of the same product or circuit board and crack the color code of that exact parts to find the exact ohms. The soldering work is really easy or take them to someone skilled and they will fix ya. (Well, didn't mean like "they will google")
( XD )

Have a good day.

The metronome speed is controlled by the Tempo setting. The metronome controls only adjust the volume of the metronome and if the metronome is heard on the input or output recording. The R24 manual is available here: http://www.zoom.co.jp/downloads/r24/manual/ . See page 20 for setting the Tempo. The Tempo button is below the Tempo label to the left of the LCD display on the right side of the Zoom R24.

I hope this helps.

Cindy Wells

Is the unit old?? Is it stored in an environment that has temperature fluctuations?? It could be the terminals on the input of the unit have dry jointed. This is when the solder lifts away from the circuit board. I have had the same problem on my ZOOM MRS1608 recording desk. Resolder the connections on the input. The base plate will problably remove easy enough to get to the point where the adapter is soldered onto the circuit board.

Good luck

Let us use a bit of logic to resolve this... I have an Axiom but it would be a lot of screws to take out to get to the part... so let us think about this. The resistor value starts with a "1" and we know it is 5% tolerance (gold). we know the resistor burnt up with likely 5 volts on it... Value could be 1000 ohms, however the voltages present (12 volts max) would NOT have burned up a resistor of 1000 ohms. The USB area is mostly 5 volts and across 100 ohms is only a quarter watt... not enough to really burn up a resistor... First thing is to MEASURE that the resistor s open... in spite of being burned, it MAY still be OK... these resistors now usually either open or remain close to their value. The resistor ALSO may be a fusible resistor intended to act as a fuse... Is the resistor open or not? is it near a resistance with a "1" as the first digit? If it is not open I suspect it is not all of the problem. In that case, look for a burned circuit trace on the board. If it is open, then MEASURE the voltage across the resistor with the power applied. If you find 5 volts, then it MIGHT be a 10 ohm used to limit the USB current to 500ma. Get back to me with your findings... I have unraveled many of these things...

no, but if you want to control anything remotely you would need one

More analysis is needed!!!

I have 50 years of electronics troubleshooting and I use the experience to isolate bad parts. I will tell you that resistors USUALLY open circuit 99.99% of the time and very very rarely do they short... I maybe have seen one do that in the last 50 years.

Most common shorts are semiconductors and electrolytic caps with other types of caps and diodes pulling up the rear.

The way you troubleshoot this is to use a current limited power supply OR put a resistor in series with a supply of correct voltage and DRIVE some current into the short... keep it around 500 ma.

Next do the finger test lookig for WARM parts.

Next use a sensitive milli-voltmeter to trace where the voltage goes to ground. The circuit traces have resistance and you can follow the current by following the voltage drop till you find the lowest voltage and you will find your bad part.