VH4 frontpanel not working -solved-

  • Thread starter Thread starter jcoriha
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jcoriha

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Hi, I have a quick question in case anyone has run across this problem before. Last week I hooked up my Rocktron All Access MIDI foot controller to my VH4 head, it was only the 2nd time I have used MIDI with the VH4, since I have been using it in the studio, or as a power section for my live rig. The other time I hooked MIDI up to it was about 2 years ago with a Tech 21 MIDI Mouse, just for a quick check, not problems at that time. When I hooked up the All Access last week, the first 4 presets were setup with channels 1 through 4 on the VH4, but then I hit preset 6, and the whole front panel on the VH4 went dead, no sound. The tubes were still/can still turn on. I looked inside, and it seemed like 1 of the 12ax7's was not lighting up, so I put a spare 12ax7 in its place, it started lighting up, but still no front panel controls are working, and no sound. I have checked the speaker, and the standby switch so no easy "I can't believe I didn't think of that" fixes. When I hooked the All Access I was initially using a 7 pin MIDI cable, but still using the Rocktron wall wart for power. I switched to a 5 pin, and there was no change. I am running a pair of KT88's, and a pair of 6550's in the power section, and they were properly biasing/currently lighting up so I doubt it is a tube thing. ANy suggestions (hopefully an easy fix I haven't thought of)?
 
Welcome to the board :thumbsup:

The All Access needs too much currrent for
the phantom supply of the VH4. In the manual
it is stated with 0,7 amps. The AA needs much
more like this.

Please UNPLUG THE AMP and take the chassis
out of the headshell. On the smaller midi board
there are two fuses with 1 and 2 amps slow blow.
One or two of them are blown and have to be replaced.

Please let me know if the amp works again and there
is no damage to the voltage regulators.

Best,
Peter
 
Thanks for the quick reply Peter!

I am on my way to find new fuses right now. Sure enough 1 of them was blown. I will post once I get back. Thanks
 
The 2 amp fuse was blown, it has been replaced, and signal is flowing through the speakers again, with full front panel controls! Only problem is that I now want to turn the thing up way louder than my small apartment can handle!

Thanks for your help Peter. Love the VH4!
 
" Only problem is that I now want to turn the thing up way louder than my small apartment can handle! "

I know that feelin' to well lol
 
brickford":32xqkv4g said:
" Only problem is that I now want to turn the thing up way louder than my small apartment can handle! "

I know that feelin' to well lol
Click to expand...

Same here. I moved out of my apartment in July and I had my VH4 since January. it was hell not being able to crank her up :( now I live in the middle of nowhere and I crank it everyday! :D
 
sadly, it seems that it has done a similar thing again (no 7 pin MIDI this time, just regular 5 pin). I was running the All Access into my Line 6 M13 for some effects programming, and then into the VH4, I am waiting for it to cool down a little, and then I am going to see if it's the same 2amp fuse or if the 1amp blew this time.
 
I actually was not trying to use phantom power either the 1st or 2nd time. I had the wall warts plugged in for both the All Access, and the M13. 1 short MIDI (5 pin) into the MIDI in of the M13, and a longer (5 pin) MIDI cable from the M13 MIDI out to the VH4 MIDI. Are you suggesting modding the 5 pin MIDI? I thought that going into the M13 was going to be safer since it can't do phantom power anyway. I am going to get some more fuses in the morning and see what I can come up with. Thanks for the input.
 
Apparently the problem hasn't been solved, or something else happened. I have been trying more fuses with NO midi connected to the VH4, and it keeps blowing the 2 amp fuse everytime. The 1 amp fuse appears to be fine, but each time I turn it on, the 2 amp blows, and 1 time I have seen the smoke. Like I said, no MIDI cables are hooked into the VH4 at this point, so it can't be M13 or the All Access still causing the problem.
 
Please send an email to peterdiezel (a) diezelamplification (dot) com
 
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