• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

GK 1001rb amp dead. Any amp tech suggestions

J

japerritt

Jan 23, 2012
15
0
#1
A friend of mine purchased a used GK 1001rb head about 2 years ago from a guitar center. He used the head daily and gigged with it about 3 times a week for the 2 years he had it. At his last gig he said the amp just went dead, volume slowy faded to nothing, yet the power light stayed on. I just got it to my place and find the power LED turns on (turns on red and after a second or 2 the power LED turns blue. The fan never turns on. The heat sink never warms up.

I'm 100% positive the amp head has an issue. My cables,cab,and bass guitar that I'm testing it with are good. Does anyone have any suggestions? I have basic electronic skills, but can't read a schematic. Any suggestions?
 
#2
Get the amp to an experienced tech if it's not under warranty anymore. I just took my 700rbI and I'm looking at 100eur(130usd); my amp however was in really bad condition. It might be a cheap fix. If you never fixed an amp... well, you just might do more damage to it.
 
#5
Come on guys.. You don't have to be a 'amp' tech to fix an amp. You don't have to be and electrician to wire a house, I've done it. You don't have to be a carpenter to build something, I've done it. You don't have to be able to read schematic to fix an amp. I actually took a 2 year electronic course 15 years ago and got my assoiciates degree, but havne't read a schematic since and don't remember all that. To fix anything, you gotta have the desire, the determination to find answers, basic knowledge of the subject.
I have fixed a CRAP ton of electronics in my lifetime by simply giving it a shot, even as a kid and have a basic understanding. The internet is an amazing wealth of knowledge and many, many, many times its something simple like a bad cable, a cold siolder joint, bad fan, bad pot (in amps). When I have an issue with something I try to find the right forum with folks willing to share their knowledge and many times they can point out common or well known issues with known fixes.

Most recently, I fixed my inlaws 47 inch Samsung DLP projection TV they were going to trash. The color wheel was bad. I search the internet for 'DLP projection TV screetching sound' and found a youtube video that took me right to the problem and it showed me how to fix it. I never fixed a TV and didnt' have a clue what a color wheel was, but I got a nice TV now in my living room!

Now, there is alot of stuff I haven't been able to fix in my lifetime, but I'd guess that 75% of the time I can figure out the exact issue. This day in age though, its sometimes cheaper to trash it and just buy a new 'one'.

With this amp I originally thought the fan was the problem since it wans't moving. I thought it might have a sensor or something that shut the amp down if the fan wans't going. After some research, I read that the fan doesn't come on until the heatsink warms up and reaches a certain temperature. Since the heatsink isn't warming AT ALL, I don't think its the fan now. Trail and error.

If I had to guess, my buddy will most likely trash it if I can't fix it and just buy a new head of some sort.
 
#7
japerritt said:
Come on guys.. You don't have to be a 'amp' tech to fix an amp. You don't have to be and electrician to wire a house, I've done it. You don't have to be a carpenter to build something, I've done it. You don't have to be able to read schematic to fix an amp. I actually took a 2 year electronic course 15 years ago and got my assoiciates degree, but havne't read a schematic since and don't remember all that. To fix anything, you gotta have the desire, the determination to find answers, basic knowledge of the subject.
I have fixed a CRAP ton of electronics in my lifetime by simply giving it a shot, even as a kid and have a basic understanding. The internet is an amazing wealth of knowledge and many, many, many times its something simple like a bad cable, a cold siolder joint, bad fan, bad pot (in amps). When I have an issue with something I try to find the right forum with folks willing to share their knowledge and many times they can point out common or well known issues with known fixes.

Most recently, I fixed my inlaws 47 inch Samsung DLP projection TV they were going to trash. The color wheel was bad. I search the internet for 'DLP projection TV screetching sound' and found a youtube video that took me right to the problem and it showed me how to fix it. I never fixed a TV and didnt' have a clue what a color wheel was, but I got a nice TV now in my living room!

Now, there is alot of stuff I haven't been able to fix in my lifetime, but I'd guess that 75% of the time I can figure out the exact issue. This day in age though, its sometimes cheaper to trash it and just buy a new 'one'.

With this amp I originally thought the fan was the problem since it wans't moving. I thought it might have a sensor or something that shut the amp down if the fan wans't going. After some research, I read that the fan doesn't come on until the heatsink warms up and reaches a certain temperature. Since the heatsink isn't warming AT ALL, I don't think its the fan now. Trail and error.

If I had to guess, my buddy will most likely trash it if I can't fix it and just buy a new head of some sort.
Click to expand...

Mr. Sparky, why did you ask for suggestions to your dilemma? Just pull out your AA degree and make the easy fix? :rollno:
 
#8
You gave me a good chuckle there, hehe. I saw myself in your post. I think it's a basist thing? Every guitar player i worked with ran to a tech for EVERYTHING. With some of them I was amazed they dared tuning their own instrument. But nooooo, bass players tend to do **** by themselves. And that is exactly how my amp got wrecked. :D The first simptome was not enough power. Then overheating. Me and my friend, who fixed a bucketload of stuff and CAN read a schematic opened it up. Well. Couple of power transistors and other elements later and we were going through fuses like a bear through honey. We probably added 70 bucks to the repair costs.

I don't want to be THAT GUY however and wish you luck with fixing this amp, even though the cost of fixing it may be as low as a 20 bucks. I reccomend you do a search on google using these words: gallien krueger 1001 service manual.

I found one for my 700. Best of luck with the repair!
 
#9
Thanks Jero182 for being kind/cool. After reading Stick Players comment I thought, "dang, did I come off as an arrogant horn tootin ass?" I was a little winded, but I type fast. Now I realize you can't avoid folks like stick player on forums, they are on every forum. Alot of people automatically 'call a pro' before giving it a shot, and I just don't think that way.

I'll try wave riders suggestions tonight and you never know what might happen! I read some other suggestions close to his last night. I'm confident I'm not going to do any extra damage to the head. I'm not going to do any component replacements that are on any of the CCAs.

Thanks
 
#10
wave rider said:
Can you run another preamp through the power amp? Or an instrument cable from effects out to effects in?

Just a thought for simple solution; dirty contacts in the effects loop.

=wr=
Click to expand...


This - see if the problem is in the preamp or power section, or even in the loop jacks/contacts... After all, it's powering up and not showing a red(fault) light - those amps are pretty bullet-proof for the most part...

I will say this much - G-K is generally pretty good about fixing their amps - even if they charge, it'll still be considerably less than buying a new amp...


- georgestrings
 
#11
You asked for suggestions, and going to a pro amp tech is a good suggestion. But, if you feel you're qualified, go for it. Of course, not knowing what you're doing, and not having the proper test equipment, you're just as likely to cause more harm than you are likely to actually fix the amp, but hey.
 
#12
If its an older then its possible part of the output went fooey. You can't really desolder these ( output transisitors ) very easily as the boards are thick and the traces are thru the board, not just one sided.

I had an older 1001 do this to me. One single tranny goes, but the best thing to do is take it to a reputable place. They should have the right type of iron and tip to replace the busted trnny, if thats what it is.

Otherwise, doing this yourself you really run the risk of lifting pads and traces..and at that point you're going to spend, I guarantee, 250 for a new board.
 
#13
OP you should realize that all of us who have done tech work in our lives have had to deal with equipment that someone has "had a go at". Normally these units take a lot of time to repair due to having to undo an amateur "fix". The advice of tech time is good advice for someone who is not trained in diagnostic processes and does not have the tools. The advent of surface mount components is an added wrinkle even for a professional.

Indeed check the FX loop I really hope it is the problem. If not, heed the advice you were given or don't. It really is as simple as that!
 
#15
Run a cable from the effects send on the GK to the effects return/poweramp in jack on another amp. That'll let you know if thr pre/front end works. Then run the cable from the effects send on the good amp to the return on the GK, that'll let you know if the power section works. Can at least try to isolate the problem to one part of the amp. If it's a power supply problem, neither section would work right.

I assume you guys made sure a mute button is not pushed in?:D

Check the DI out both pre and post eq as well. That kind of stuff can at least help narrow things down.

Are the speaker outs fused or have breakers that won't reset? Can try jumpering around them. Of course, use an old crap speaker you won't miss when doing that.
 
#16
will33 said:
Run a cable from the effects send on the GK to the effects return/poweramp in jack on another amp. That'll let you know if thr pre/front end works. Then run the cable from the effects send on the good amp to the return on the GK, that'll let you know if the power section works. Can at least try to isolate the problem to one part of the amp. If it's a power supply problem, neither section would work right.

I assume you guys made sure a mute button is not pushed in?:D

Check the DI out both pre and post eq as well. That kind of stuff can at least help narrow things down.

Are the speaker outs fused or have breakers that won't reset? Can try jumpering around them. Of course, use an old crap speaker you won't miss when doing that.
Click to expand...

Thanks for the reply and detailed instructions. I just did some test. The XLR direct out works, both pre and post. The effects send from the GK to another amp works. The mute button appears to be working, red LED when muted. I don't have a speakon cable to try those jacks. I'm testing using the two 1/4" speaker jacks. I dont know anything about speaker breakers? I don't see a breaker/s. Here an important detail- When I turn the amp on I the power LED light comes on for about 3 seconds. It thens turn blue and right when it turns blue the I have output or sound from my bass cab for about 1 second. After that I got nothing. It will do this each time I power it up. The head has been on for an hour now and the heatsink is still cool, as if its getting no power, and the fan never comes on. Actually, the fan does spin for a split second after the power button is pressed. Any other ideas of what I can check or try next?
 
#17
You've isolated the problem to the power section of the amp....that's progress. Playing for 1 second, then quitting until it's turned off and on again, could be caps discharging the initial current they stored when they got the inrush from turning on the amp, but then not recharging. This is a wild guess, not a diagnosis. You've done some legwork to make it easier on the tech to finish the job. The other layman's option would be to just start replacing parts until it works again, usually not the wise thing to do.:D

I don't know how the bias being out of whack would sound, but SS amps are biased as well. Usually with an internal adjustable control that's set at the factory and isn't accesible to the user.

That's close to the extent of my "techiness" when it comes to amplimafiers.:p
 
#18
japerritt said:
Thanks for the reply and detailed instructions. I just did some test. The XLR direct out works, both pre and post. The effects send from the GK to another amp works. The mute button appears to be working, red LED when muted. I don't have a speakon cable to try those jacks. I'm testing using the two 1/4" speaker jacks. I dont know anything about speaker breakers? I don't see a breaker/s. Here an important detail- When I turn the amp on I the power LED light comes on for about 3 seconds. It thens turn blue and right when it turns blue the I have output or sound from my bass cab for about 1 second. After that I got nothing. It will do this each time I power it up. The head has been on for an hour now and the heatsink is still cool, as if its getting no power, and the fan never comes on. Actually, the fan does spin for a split second after the power button is pressed. Any other ideas of what I can check or try next?
Click to expand...


The fan doesn't run on those amps all that often - they typically run pretty cool, and you have to push them fairly hard for a little while before the fan ever comes on - and even then, it won't run all that long... This is normal fan operation for these amps...

Do you have a way of sending a known good preamp signal into the effects return to see if the poweramp is functioning??? Also, have you tried running a patch cable between the send and return of the effects loop??? If that makes the amp function normally, it's time for new effects loop jacks, because their contacts aren't working properly...


- georgestrings
 
#19
Again, Thanks guys. Georgestrings, Effects send from the GK to my fender blues deluxe workds fine. I get NO output/sound from the GKs effects return, coming from my blues deluxe. I'm with Will, its got to be the power amp section. If I could order a replacement board myself, I'd do it if the price was right, but I just didn't a quick search on the boards part number and came up empty. I'll do some searches for 'gk 1001rb power section' while I'm at it, but I'm guessing my limitted skills are tapped out.
 
#20
japerritt said:
Again, Thanks guys. Georgestrings, Effects send from the GK to my fender blues deluxe workds fine. I get NO output/sound from the GKs effects return, coming from my blues deluxe. I'm with Will, its got to be the power amp section. If I could order a replacement board myself, I'd do it if the price was right, but I just didn't a quick search on the boards part number and came up empty. I'll do some searches for 'gk 1001rb power section' while I'm at it, but I'm guessing my limitted skills are tapped out.
Click to expand...

Likely the only place that would have a whole board would be GK, and I doubt they'd let one go to anyone other than a tech repair business or "authorized service center". A tech with the right diagnostic equipment would track down the few bad parts and replace those rather than an entire board. I don't know what GK's warranties are like but 2 years isn't very old. It may have had a lot of hours on it in those 2 years but still, that's not much compared to their usual 20-30+ year servive life. Might be worth a call to GK.
 

Latest posts

Top Bottom
Back