Vox VT30 Locked Up

[drewl]

Got a VT30 with a bad preamp or processor.

Well, when you power it up the bank and channel lights just keep flashing, no response to any buttons or controls, power amp seems to be okay.
Tried resetting unit with no change.
Looks like the proper voltages are there and the clock is working. anyone have a similar problem before I start going through it?

Thanks.

[J M Fahey]

Nobody repairs computers at component level, replace full motherboard.

Keep/repair the analog part, ditch the digital one.

Or in other words: those amps are disposable.

[drewl]

Yeah, just taking a stab at it.

I doubt the preamp board is available unless I find someone selling one, or one with a bad power amp.

[nosaj]

Have you tried a factory reset?
1. Turn off the power.
2. While holding down the [CH1] and [CH4] switches, turn on the power. When the
BANK and CHANNEL LEDs start blinking, release the two switches you had been
holding down.
HINT: If you decide to cancel initialization at this point, press the [TAP] switch.
3. Press the [BYPASS] switch. The BANK and CHANNEL LEDs will change from blinking
to lit, and initialization will begin. In one or two seconds, initialization will be
completed, and you will switch to Preset mode.
NOTE: Never turn off the power while initialization is in progress.
17

nosaj

[drewl]

Yes I did, but thanks for the effort.

Those LED's are blinking like it's stuck in the initialization stage.

Even checked the switches to see if they work to reset the unit.

[g1]

Is CPU reset line getting it's proper level/command ?

[nosaj]

For everyone else. service manual attached.
nosaj

[drewl]

Is CPU reset line getting it's proper level/command ?

oh nice, didn't see that schematic
Now I can see if it is.

Thanks

[Marshtech]

CPU Reset is something to try for sure. Even when I was trying to bring a pedal or amp (with computer chip) back to life that I wasn't totally familiar with, I've had good luck performing a reset - either by instruction manual method or finding the pin on the CPU myself.

[drewl]

Wow, so much easier to repair stuff with a schematic, thanks nosaj

No 3.3v on IC2, which I suspected as it had no supply voltage, due to a bad via to the other side of the board.

Installed a jumper wire and it came right up.