G9 Sccccccarrrrrrryyyyy noises

[isamee]

So I fired y up my G9 for the first time today. The tubes lit and everything looked good, no smoke! Unfortunately there is a considerable amount of noise and the mic is not working. I ckecked for phantom across my XLR and it read 48. There is just a buzz, and when you crank the gain up it squeals. I double checked connections and everything looks ok. One other thing, after being on for a few minutes the lights fade and the unit shuts itself off.



Any ideas?

Please help,

Thanks

 

[pucho812]

1.read the metas

2. check traces on the PCBs

3. recheck all caps and solder points

 

[peterc]

Try without a mike, & put your fingers on the back of the input XLR's you should hear a buzz if it works.

One other thing, after being on for a few minutes the lights fade and the unit shuts itself off.

Are the 12v regulators on a heatsink? Very important.

Does the same thing happen in both channels? Take the valves out of channel 1 & get the other working first.

How are the other voltages?

Peter

 

[Vetsen]

I had the same problem. It looks like the "mic line 48V" switch is not quite right on mine. So I unsoldered the relay and "inserted" the mic right before the input transformer. Also you can try inserting a jack into the DI to bypass the input transformer too. Clean sound, and the gain stages are working. I just need to figure out the switch and relay.

As for the unit shutting down, it is most likely the 7812 overheating. Have you installed a heat-sink? Like Peter said, it is very important. Mine shuts down after about 30 sec without a sink.

Be really careful around the TL783. There is >200 volts on the mounting base. If the heat sink is not electrically insulated, Don't Touch It!.

Vetsen

 

[louder]

alo
as for g9 shuting down,it is most certanly,7812 overheating.
try this>connect 7812 to the chassis,and insulated.
as for the noises,i remember people reporting that when g9 uses oep trannys,but there is a cure which i do not remember right now.read g9 thread.
best regards
pedro

 

[Gus]

after you fix the power problem turn the phantom off and try a dynamic microphone if you did not do so.