Vox AC30CC2 Repair
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- เผยแพร่เมื่อ 28 ส.ค. 2024
- This one came in with some arcing and microphonics in one of the output valves. There was evidence of them all overheating. They were replaced, then some component value changes to ensure the bias is toned down to a more reasonable level, and that modern production EL84's can be trusted to last a reasonable time.
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Great video. My cc2 just gave up and I'm trouble shooting. This'll help heaps. Thanks! Greetings from an Aussie abroad.
Bought an AC 30 CC2 a couple months ago used at a shop... had to take it back twice right after getting it home.. wasn't turning on the 1st time...it was a tube and fuse... 2nd time just needed the input jacks properly cleaned...deoxit...etc...then it was right...sounds beautiful! Cool to see the guts of it displayed...was curious what tubes are in it...thanks from Livermore California... appreciate you sharing this! 😎🎸🤘🐦
Had and gigged mine for 13 years now (wow). UK blues nicely broken in and re-tubed 4 times with jj's. I run mine 'warm' @ 22watts. Love the sponge. 😁 What goes wrong? First off just don't use the feckin standby switch. Trust me! Second the master volume pot needs a good clean every few years or it gets very crackly/random in-out issues. There was an issue where it kept cutting out at stage volume and would 'pop' back in if I whacked the guitar: turned out to be the ribbon cable joining the pcbs vibrating loose. Hot glue gun solved that. Other than that, I upgraded the reverb tank and modded the tremolo to have about twice as much top speed (its a ss trem so easy to do). I'd say stay away from the Lyle Caldwell mods et al. The bright cap and screen resistors etc. Imho they sound like crap and I can't understand why you'd want to make the cc2 (a late 60's voiced ac30) sound darker, unless you were still using the stock ceramic speakers. All the people who say these are too heavy just need to stop eating soy. Best amp I ever owned. My only other amp is an origonal JCM 800 combo, which reaches the (very few) places the cc2 can't.
@@cgavin1 Thanks so much for the reply... yeah... this is an amazing sounding & feeling amp! I've written your notes down and will have on file for future reference! When I first heard this in the store I was immediately handing over that $500... and though it took 3 returns to the shop to fix the issues with cracking etc just as you describe... it's a dream to play through! Just LOVE IT! 😎🎸🎹🐦🤘
@@cgavin1 about the stand by switch, is it better to leave it on play mode all the time?
@@brunosucheck1191 Yeah, I don't use it at all. If I am playing out I just turn the amp off if I am not going to use it for more than 30 minutes or so. The rectifier protects the circuit on power up. I have had the same Mullard GZ34 in mine since day 2.
@@cgavin1 Thanks man, Just got a cc2x today, never owned a vox before, been playing rivera and laney
Regarding your question about if the screen and grid resistors have been changed in the amp you were working on, no I don't think so. The grid and screen resistors are the exact same value as mine, and mine has never been touched. I've now got mine running, but the screens are frying. I think part of the problem is the whole amp is over volting because the output from Gz34 is 12V higher than the schematic says. Sorry to flog this really old dead horse. I've been referring to this video a lot while working on mine. The schematic is an effing mess.
Update: I just took my AC30 CC2 out of storage (about 6 years). Put a new set of valves, including a new GZ34 in it. De-oxit in all the pots and valve sockets. Made sure the standby switch was in the ON position (so it is NOT in standby). Turned on the power, as soon as the rectifier warmed up it arcd out, blowing the fuse. Suggestions? Thanks 🙂
The rectifiers in these amps (or should I say, the rectifier part of the circuit) is a f***ing c**t. I gave in and fitted a solid state rectifier.
Does anyone know where Vox originally came up with its circuit design?
As in Marshall and Mesa modded Fender circuits. Leo took his designs from RCA circuits. Did Vox do the same thing or did they come from somewhere different?
Brad, you bring joy to this world and I'm grateful to share it with you, mate! - QQ: is the reverb in these VOX's known to be low? I have mine cranked and compared to a fender it sounds like it's at 10% - would the master volume affect this circuit balance/mix? I keep it pretty low to keep the natives from getting restless but I'm finding I have to patch a reverb pedal into the loop to get the mix I want - curious if you know how to baseline the verb tank healthwise?
The bias is selectable.I had JJ el84's with about 500hrs - no issues,JJ's are nothing special either.I swapped them out before they decide to fail with Russian 6p14p's rated for 5000 plus hrs.They're probably the last el84's I'll need in that amp because they handle even more voltage and abuse.The only issue I ever had with the amp is defective standby design - I blew a fuse when using it.I no longer use standby ,it's not needed on tube rectified amps anyway.
I also increased the TB channel coupling cap value for more low end for a fuller clean-ish sound.I may reduce the cathode bypass cap on the first gain stage to Marshall territory but so far so good - if I want that mid heavy and/or chimey Vox sound its still there,I just turn the bass dial lower.
I've got two of these amps. I had the R6 and R7 resistors changed to 220k
Just did that mod on mine. Way better
Should never change to 220k value for those resistors the op amp puts out too much gain and will ruin the vox classic tone. Was an old mod from a guy in the us that has a youtube channel. he doesnt do these mod anymore.
When buying one used, is their anything an amp tec should change or replace. This is for future reliability. Nothing is wrong with the amp currently. Got mine used from a reputable dealer that is authorised to sell new and used. Mine has one year used warranty.
I have what I think is a 2003 AC30 and a 40 + year old Traynor amp both with a high pitched whistle, more pronounced in the Vox than the Traynor. Any suggestions on what I can do to trouble shoot them?
I agree.... Who cares about the Queens birthday.... Just give me my day off.
Lots of great info on here, you're clearly super knowledgeable. I'm diagnosing an AC30CC2X which has some odd issues, chiefly no top boost channel and a synchronized vibrato type effect and flashing standby switch when I turn it off. People have suggested this may be a bad coupling capacitor. I can point out the filter caps in their block diagram, but have trouble on their full schematic. Could you point out which capacitors are the coupling capacitors?
Contact me on the Facebook page, and we can dig a bit deeper, mate.
That pulsing on powerdown is normal on this amp. If you don’t know which caps are filtering I would hire a pro. Very dangerous.
No top boost is probably v2 but possibly v1.
I've been having problems with my AC 30 completely shutting down and blowing tubes when switching on the Standby switch ... any thoughts? Is this a common problem ?
This is a known issue. I’m having the same problem, I think I blew the rectifier tube.
I read that you shouldn’t use the standby switch at all
Just keep the standby switch on or better yet get a tech to remove it entirely. Very very common issue I’m afraid.
Don't use the standby. The GZ34 is quite effective at regulating the current.
Source: 5 years of just turning the amp on and letting the rectifier handle shit
Don't use the stand by!
bought an AC30 CC2 from my friend..it's working fine.....but unfortunately when i inspected the pcb baord the fusible resistor ( R188) burned , and two caps (C148 & C149) is slightly bloated..kindly advice & what is your thought on that...many thanks ..
What do you think you should do?
I have a car with a flat tire. What do you recommend I do?
@@TheBoomtown4 Buy another car! lolll
Hello
Could you tell me the function of every preamp tube? V1, V2 and V3
Thanks
The schematic is freely available online.
Where do you get the ceramic stand offs?
Digikey. CER2, CER3
Is that cofee you drink from yesterday or what?
6:51 😂😂👌😁
That looks like a service disaster
Hey man, where are you?? You sound like an aussie or a kiwi.
Aussie, mate. Where are you from?
@@BradsGuitarGarage i,m an american who lives in japan. I subscribed because i love amps but i,m a drummer. I want to build an amp but my wife won,t let me.
They're not 80 bucks a quad anymore mate
Bloody oath. Don't I know it!
I stocked up before the pricing hit the roof as soon as I heard troops were amassing at the border.
I got some issues here: original problem was bad rectifier tube and fuse. Replaced All tubes and fuse, not its has this crazy sound. Could you give me advise? Here is video: th-cam.com/video/eHGmKMvTxB4/w-d-xo.html
Sounds like "motorboating" due to coupling between stages that shouldn't be coupling. Likely due to bad preamp node filter capacitors. If you've not done advanced amp repair before I'd suggest taking it to a tech.