#1
O.K., I bought a fairly awsome amp for 100$ U.S. a couple months ago. Randall pro-tube 2000, all tube, 5 12ax7 pre, 4 el34 power, two chanel, spring reverb, awsome gain channel and nice jazzy cleans. problem is, it stoped powering up. I took it apart, and lo and behold, it was maybe 30% stock at most. Most of the mods I understood, carbon comp resistors and changing out some capacitor values and such, but whover had it did a LOT of stuff to it. There is an spst switch in the back of the amp labled "RESET" and it does exactlyt that, I just don't know how. All kinds of crazzy stuff. Moral of the story, I need a schematic. I have searched and googled and even emailed Randlall, but to no avail. HELP!
#4
Read my post, cognitive one, I already spent a couple hours on google.

Any real suggestions or help?
#5
hmmm...

I found this in the reviews on HC, although it's about the pro tube 1000...

Quote by Review On Harmony Central
Here's where I differ from the rest of the reviews here. It did take me two or three emails, but I did get a copy of the manual and schematic of the amp... even though it was discontinued. I thought that was pretty good so I'll give it an 8... it did take more than one email.


So from that, I guess if you bug Randall enough, they'll eventually be usefull..

I'll spend a few more minutes looking for a schematic for you,. though.. I've got nothing else to do right now..
#7
Randall probably isn't giong to give you a schem. They don't want people building their amps. This is why you won't find one online. If anyone can find a Randall Pro-Tube 2k schem online, I'll personally suck their ****.

I don't think you'd understand most of it anyway. It'd be VERY complicated. Yeah, yeah. I'm a douche and all that. Sue me.
#8
I can read a schematic well enough to understand the changes that have been made to it. For the most part. And like james4 said, some guy on harmony central got sent one, plus, I told them what my situation was, that I was reparing an amp. It is in the best intrest of Randall to allow people to repair amps they stopped making 16 years ago.
Also you are probly on vicadin anyways, so I won't fault you for being rude. (And partially right)
#10
No problem. I took a vicadin once after a surgery and almost got in a fight. makes my mad, jumpy, and paranoid. after one, I just delt with the pain, even the time I halfway sliced my finger off. (Don't ask) I'll put som pics up somtime tomorrow, cause i'm worried about a couple things. Mostly the fact that three of the 450 volt big electro caps have been replaced with ones rated at 250. One of the reasons I need the schematic so bad.
#12
Nope, conked out on me. Can't even gett it to power up on standby. I am pretty sure of the old rating because the guy only replaced 3 out of 5 caps, and the old ones are rated at 450 V, the new ones are 250V. A little worrisome.
#14
#15
If you look at the gut shot you can see the two biggest caps on the left. they were attached by cutting the prevous caps then soldering to their legs so that the circet board did not need to be removed. Lazy...
#16
No comments on the pics?

Im on my third email lto randall by the way.
#17
Sorry, but those pics are friggen huge and I have dial-up. The reset switch is prolly a breaker that, well, broke. Does it stay in when pushed? If not, it's busted. Replace it with another breaker or a fuse holder.
#18
The switch looks OK mechanicly. Man, I wish I had a schematic. Randall, help me out man...
#19
The "push to reset" switch is a breaker. If it doesn't stay in, it's broken. That's probably your problem.

WTF is with the alligator clip?

Are the new caps part of the H.V. power supply filtering? I would think that a cap rated for that low of voltage would have exploded a long time ago if that was the case. Either that, or the power supply's voltage was reduced.
#20
alligater clip is discharging the caps. not sure about the caps or voltage, thats why I need a schematic. the push to reset never stayed in. mechanicly, it is like a stomp switch, and it worked with the like that fine for a long time. looking at the amp again, the lone diode on the far upper left looks kinda jacked up. could somthing like that be the problem?
#21
Hey, that IC that I see (no pun intended), (fine, there was pun intended, haha): Is that socketed or does it just look like it? If it is, buy a new IC, and swap it. It's highly unlikely, but possible.


Actually: That diode, is that in any way close to the power supply section? If so, that could be a voltage protector and if that's messed up: Amp goes poof. Get a bigger pic of that diode, m'kay?
Gear:
Schecter Hellraiser Deluxe
Boss DS-1
Crate GTD65

GAS List:
Mesa Boogie Dual Rectifier Roadster
#22
Well, like me and Losenger said: the reset breaker may just be broken. I had a CB power supply that had a broken breaker in it that someone bypassed, and I replaced it with a fuse. Just try replacing the breaker...
#23
Yeah, the IC is socketed. I'll try that.

I'll get pics of the diode as soon as possible. Not sure what it does, but I was thinking it could be a voltage protecter. That could deffenatlly cause the problems I have encountered.

Thanks for the help, guys!
#24
Try checking the continuity of the breaker with an ohm meter.

FYI: You have your alligator clips connected to the negative side of the cap. It's not discharging anything, unless it's a positive ground amp

If the amp doesn't power up at all, it's 99.9% unlikely the chip has anything to do with it.

What diode are you guys referring to?
#26
Well, it wasn't the breaker. It must have just been a dirty contact somewhere. I tested the breaker, it was fine, checked all the solder joints, no problems there, so I just gave the amp a good cleaning. Retubed and it was fine! same tubes same everything, and now the background noise is way quieter as well. Stupid Randall never did email me back though, I must have emailed 5 times, the dirtbags...
#28
I hate it when something begins to work again without determining the root cause(s). Can't learn much when that happens. Congrats, anyway!
#29
Yeah, I know what you mean. But I'm just happy to have this thing working again. It must have just been some grime or gunk somewhere. I had to break in new speakers in the 4x12 I just restored useing that amp, so much fun. Living in the middle of nowhere has some advantages.

I'm still look for that schem, btw, if any of you run into it let me know.