Troubleshooting
* The amp does not power-up after you have switched the power on.
The control lamp inside the power switch (17) does not light.
-> Is the mains cord connected to the receptacle / live power source ?
-> Is the power cable you are using intact ? Try another equal mains cable.
-> Is the mains lead properly connected to the AC Power Inlet (18) at the amp ?
-> Possibly the mains fuse (19) has blown, unplug the mains cord from the mains connector
and the receptacle and check the mains fuse.
* The amp does not power-up after you have switched the power on. The control lamp inside the
power switch (17) lights up but the Channel & Mid Boost switching functions do not react,
i.e. the corresponding control LED's do not indicate an active function;
moreover no sound is emanating from the connected speaker.
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> Possibly the internal mains fuse has blown. Let this fuse check by a professional technician.
* The amp fails to respond when you try to control switching functions remotely
using a footboard such as the Z-4 or a MIDI switcher such as the ENGL Z-11.
-> Are the footboards or switching loops connected to the corresponding footswitch jacks (20, 21) ?
-> Are the cords you are using stereo, intact, and wired properly ?
(Refer to "Wiring of Principal Connectors" for pin assignments.)
-> If you are using footswitches other than an ENGL Z-4 or Z-11, are the switches or relays inside the
boards or switching loop systems off / on Single Pole Single Throw (SPST) switches? In other words,
do these switches continuously connect to GND when you wish to activate the given function?
If you're unsure about the answers to these questions, consult an authorized service center or a
professional specialist.
* The amp is not providing an output signal / no sound is emanating from the speaker.
-> Is at least one speaker connected to the speaker outputs 4 ohms, 8 ohms or 16 ohms (26, 27, 28) ?
-> Is the power amp activated (Standby switch to ON) ?
-> Are all cords (guitar, effect, and speaker) connected properly and are they functional ?
-> Unplug connected effectors and see if the preamp works fine without these peripheral devices.
-> Is the Noise Gate activated in the Lead channel and the Threshold (22) knob set to a high value?
Deactivate the Noise Gate (22) for a quick check.
-> Are the active Master knob and the Gain and Volume knobs set to a value greater than 0 ?
If any of these knobs is set to 0, no signal is routed to the amp's outputs.
-> You may be looking at a faulty tube or another defect. In this case,
be sure to take the preamp to an authorized, professional service center.
* The speaker is emitting humming noises:
-> Is there a connection (for example, via a shielded circuit) between the amp and another device
that is grounded via a power plug of its own?
Two or more circuits sharing a common electrical ground line can cause audible hum.
If low-frequency noise is emanating from your rig, be sure to consult a specialist.
-> The amp and mains grounds are not connected properly or are altogether disconnected.
Have an experienced specialist check this.
-> Cords connected to the input or effect loops may not be shielded properly.
Replace them to check if this is indeed the case.
-> The amp or speaker cords may be picking up interference from powerful magnetic fields
(for example, of nearby power transformers or electrical motors).
Reposition the amp and connector cables.
-> The amp or speaker cords may be picking up radio signals, for example, from activated mobile
telephones or powerful local transmitting stations nearby.
Switch off mobile phones while troubleshooting noise problems.
* The electronic power amp protection circuit has tripped:
-> The given power tube is defective and must be replaced if the electronic circuit breaker continues
to trip after several attempts to reset the Tube Monitoring System by flipping the Standby switch
off and back on again.
IMPORTANT, PLEASE NOTE:
do not flip the Stand By switch off and on in short time intervals
if a P.T.M. LED (15a-d) indicates a tube failure. Let a few minutes pass by before you engage
the poweramp again after you have switched it off.
-> The amp has been overloaded, perhaps by excessive volume levels, mains over-voltage,
or the wrong output impedance (the impedance setting does not match the connected
speaker's impedance).
