From David Bivins Sent Mon, Sep 30th 2019, 02:26
From David Bivins Sent Mon, Sep 30th 2019, 02:26
Check physical connections/joints. I had the same symptoms after buying one f= rom a reputable seller on Reverb, and after I returned it he reported that i= t worked correctly. I could only conclude that shipping jostled something.=20= > On Sep 29, 2019, at 9:26 PM, Brian Willoughby <xxxxxx@xxxxxxxxxxxx.xxx> wr= ote: >=20 > Hi Ben, >=20 > I haven=E2=80=99t looked at the schematic, but 4.5 V would be the virtual g= round reference for a +9 V power supply. That M5218L could be working proper= ly, because 2x =E2=80=9C0=E2=80=9D equals =E2=80=9C0=E2=80=9D (substitute 4.= 5 V for =E2=80=9C0=E2=80=9D when working with virtual ground). >=20 > Your problem may be earlier in the signal flow. >=20 > Brian >=20 >=20 >> On Sep 29, 2019, at 5:32 PM, Benjamin Clark <xxxxxxxxx@xxxxx.xxx> wrote: >> Hi all, >>=20 >> I turned on my MC-202 today and it didn't seem to be making any sound. Af= ter cranking up the output, I could hear the synth was working at a very low= volume. It's the same situation from the headphone jack. >>=20 >> Anyone run into this issue on a MC-202 or SH-101 before? I'm guessing the= M5218L dual op amp is bad since it amplifies the synth for the headphone an= d output jacks. The power supply input to the chip is good (9 V) and these a= re the measurements I'm getting from inputs and outputs: >>=20 >> non-inverted input 1 and 2: 4.3 V >> inverted input 1 and 2: 4.5 V >> output 1 and 2: 4.5 V >>=20 >> They are setup as non-inverting opamps with a 100K input resistor and 100= K feedback resistor, so I think the output is supposed to be 2x the input? A= ny help would be appreciated. >>=20 >> Thanks, >>=20 >> Ben =20 >>=20