Hello,                                                                                                                                                                  I need more help on understanding electronic component lingo.What does IRFP140. IR 77.407L with a 09 underneath it stand for.Thanks for all the INPUT.                                                                                                                                                                  ADV

Can anyone direct me to where I can purchase OP Amps.I tried Loud Technologies and had no sucess.Any Help Will be Appreciated. Thanks ADV

Hello, Thanks be to all with your in put. Man that robot was 21st century.LOL!After reading that I should build my own pre-amp. Sounds like a plan.Would it be possible to gut this ss amp and build a good tube amp out of that chassis and cab? What could I salvage off of it that would interact with atube amp? I think i will do some home work and investigate another alternative. Once again I do thank you all for your experience and advice. ADV :dbtu:

http://www.youtube.com/watch?v=loSllHtY9q0  Hello Roly this is similar to what my amp is acting like, the hellocopter sound first then a slight siren noise not as prominent as in this vid though. ADV

Hello Roly, Thanks for the response.

http://www.youtube.com/watch?v=loSllHtY9q0    This is close to what mine is doing but just the opposite in sound noise. Mine is the helocopter 1st and then a slight siren noise not as prominent as this amp on y/t. P.s. Turn your sound down this guitar player will rattle your brains. Thanks adv

Hello,I tried crossing FX with another amp and the noise came through that amp also. So It must be in the pre-amp stage.Hell, I feel sorry for the people that have to assemble this amp in the first place. On youtube,under vox probelms or vox siren noise there is a sample of a amp doing almost what mine is doing, The helocopter is the same, but the siren sound on my amp is not as prominent. That is if anyone wants a sample of sound. Thanks ADV

Hello, I thank all of you for your experience and input.y es, I agree that its above my knowledge to even try to work on this type of amp and I would take it to an experience person.I have tried to reset to factory settings and I went ahead and cleand and lubed any thing and every thing.I have noticed though that the noise gets louder when I turn up the wattage on the back of the amp. I went to trusty you tube and found were other people have the same probelm with thier vox.One peron freeze sprayed a IC and had some luck with it I think he said it was the final amp near a heat sink? I know you get what you pay for.I didnt pay much. Ive made a few dollars with it so its all good. I just dont want to have to pay more to repair it than I  payed for it .Well I need to get back to ,As the amp turns. Thanks again. adv

Hello Roly, I thank you for the service manual.Our computor has been down, Im just now getting a chance to reply.Do you know if that was for the 2 channel or the 4 channel. Mine is the 2. I will figure that out looking at the schematic. Im a newbie to the solid state amp scene so I may have to ask more question.LOL! I have tried re-setting to factory settings.( no change) I put another ax-7 in it, took awhile for it to start acting up again. Maybe that original tube has some issues as well. I think that 1981 super champ i have has a send and return on it. I will try out what you said.Well Im going to start lookig at the scematic so once again thanks, adv

Hello, Thanks for the response.I went ahead and did what you said to do. Heres what happen when I jumped the return and send.The sound got louder and I can put my hand on top of the left side of the amp and a pronouce flange sound comes out of the vent on top of the amp.When i first plugged in and powered up it took about 3 mins. for it to make the noise.I have already reset the amp to factory settings.(No change).Im just wondering if a tube could be at fault or a IC going bad.Once it starts making the noise after warm up, The noise is constant( Like a loop).Even though I set the gains , master at zero or on ten and the eqs on 5 it still does the same thing.I have to go to work now so I will read my post tonight. Thanks again for your help.I really appreciate your response. ADV

Hello , Ive recently had a noise out of this amp. Without a guitar plugged in it makes a noise. I will descibe the sound which may have  some humor.It sounds like a ticking or farting sound and then like a zooooooot sound. then it will quit and repeat the process.It does it on any channel or manual switch, pre-set,etc!!!Can anyone help a struggling muscian out on this probelm. Any help will be a great help.     Thanks adv

Hello JM, Thanks for responding! This amp has two channels. On the front of the amp is where the external speaker jack is and a foot switch jack. It has 3 effects knob(chrous,delay and a reverb).Whats wierd about the amp is It doesnt have a effects loop on it.find it strange that I would get shocked from just plugging in a cord to the ext. speaker jack.I thought that it could be a earth ground jumping some whereThe kid that owns it said he tried to plug a 4 10 cab to the ext. speaker and after that it went down hill from there. I notice that the in put jack seem to be week just by plugging in the cord to it or it felt that way to me. Im going to do a continutity test on it to see what happens! Do you have anymore suggestions? Thanks adv

Hello I have a crate gfx 120 amp. Im getting no sound out of it when I plug in an guiter. I can unplug the guitar and touch the end of the cord and still I dont get any signal noise. When I plug a cord in the external speaker jack and touch the end of it, I get a low voltage shock through my fingers. Does any one know what my probelm could be? os steps on troble shooting the probelm. Thanks for the help adv

Thanks Enzo for the lesson, You were very helpful ! Three cheers to you!  ADV

I have some questions about testing electronics. Do I test a circuit with amp pluged in or unpluged on in put stages? Can I discharge a electrolytic in the pc board itself? How do I test a IC or operational amp? On a schematic (TP) does that stand for test point? Can I use a muti tester for these procedures? Thanks ahead of time for any input and lessons!

 25001h4_.pdf (511.6 KB), 25001p41_...pdf (205.1 KB), 25001p42_...pdf (58.3 KB), 25001p4_.pdf (114.4 KB), 00-277-01...pdf (156.6 KB), 00-277-01...pdf (64.1 KB), 16-13301w...pdf (705.2 KB), 00-277-01...pdf (190.9 KB)  Hello, J M Fahey, I pasted this info from what I got from loud tech. I hope that this is sufficient info.When the representative sent this to my e-mail I opened this through adobe reader.Thanks for your efforts! Jack I replaced the pre-amp tubes.The owner manual I had originally said to do that.It didnt change much! Thanks to everyone for your input! ADV