Soundcraft GigRac 1000ST, major problems ? blown?

[phlash]

I am having a problem with the board listed above. Its an 8 channel powered mixer containing 2 internal 500watt amplifiers. When in good working order, the VU meter lights on the right hand side when first powered on, will light up for both the left and right channels all the way to the top, and then drop back to nothing.

Now the problem I am having is no matter what outlet, or what 110VAC power cable is used, its the same issue. When the amp is I get the VU meter blinks on the right channel rapidly until about halfway up the VU meter (there are 20 total LED lights, 10 per side) to the 5th or 6th light, and then goes to the 4th light, then the 3rd then I get absolutely NOTHING. no sound, no power no meter. the fans do no kick on at ALL like they used to. I used to hear a whirring sound as the amp first kicked on and then it would quiet back down. now I thats all I get. I can if needed take a video and upload to YouTube. Any Ideas? The boards main fuse is good. I have checked it with a meter, and the switch is good, and is reading 110v.

Thanks so much for any help.

Mike,

St. Louis

[Enzo]

Vey likely one of the amplifiers is blown, and the unit also probably has a "switching" power supply. The supply shuts itself down the instant it detects the excess load from the blown channel. That would be my guess.

[phlash]

how can I be sure of the problem? I went on soundcrafts website, and there was a direct link to look up what power supply unit that you need dependent on your model, and this would SOUND to me like a PSU problem but I was just looking for some other answers. more concrete, or perhaps a way I can check things out.

[Enzo]

Yes, it could be the power supply itself at fault. In my experience it is more likely a blown amp channel, but certainly anything is possible. Those modern power supplies have a variety of protection circuits on them, and they tend to shut themselves off when they detect a problem.

In my shop I would do a quick check for shorted output transistors, and look for some connections to disconect the power amps from the rest of the system.

[phlash]

I suppose I will take it into the shop down the road, and hope they don't hose me too badly. I have never used them before.

[chipprogr]

Mike, im not far away from you, Evansville, IN. If you would feel comfortable in shipping it a close distance, I dont charge for estimates. You can verify me if you like. Pro Audio Services I am a service center for several music stores and guitarcenter chain stores in my area. All you would be out is shipping if you need a 2nd opinion. THanks -Eric

[phlash]

I may end up doing that. Im going to take it in Wednesday when I get paid, the shop down the street does mostly TV repair but I would assume most PCB and electronics troubleshooting all works out the same way, its a $20 upfront estimate I found out, and then if its not too bad they will apply to my repair. I don't want to spend too much on this as its a backup board for me, and I really havent used it in over a year, its been sitting in the closet, but I am trying to get another PA system up and running so that I can have someone else run karaoke for me and I can make money for owning everything, and its a SUPER easy board to teach someone else how to run.

[phlash]

Mike, im not far away from you, Evansville, IN. If you would feel comfortable in shipping it a close distance, I dont charge for estimates. You can verify me if you like. Pro Audio Services I am a service center for several music stores and guitarcenter chain stores in my area. All you would be out is shipping if you need a 2nd opinion. THanks -Eric

Eric, have you seen many of these boards go bad? Being that I am sure Guitar Centers sells A LOT of them?

[chipprogr]

There is alot to be said of a product by how much a technician sees it in the shop for repairs. In over 20 yrs, i have had maybe 3 pieces in the shop from Soundcraft. I own their products and have always been happy with their build quality. Only issue ive ever really had were ribbon replacments on touring boards. Ive never received any soundcraft gear from Guitar Center, nor have i ever seen any to be sent out for repair when im at the stores.

[phlash]

man that floors me...this is my 3rd GigRac 1000ST that I have been through. The first 2 were clipping as soon as they were turned on, which I found to happen when there was sound coming into the board and channels being turned on during the "warm up" period. Once I made sure all the channels were turned down and that the mains were turned down, until after I heard the "CLICK" and the fans kick back off, this one lasted quite a while. I just wish I knew what was wrong with this one.

[phlash]

UPDATE

UPDATE

When I leave the board on, and turn on the phantom power, after a few seconds the light will come on and fade out, and then in a few seconds the light will come on and fade out. There is also a light sound coming from the speaker (i had previously not had one plugged in.) It sounds like i am taking my finger and tapping on the actual paper cone with medium force. I know none of you can fix this via the internet, but after doing hours and hours of research to try to find information, there is basically nothing on this particular powered mixer. Hopefully this thread will be useful to someone else. After I get it back from the shop, I will also post up what the problem is/was.

Mike

[Enzo]

Which is a pretty consistent description of a power supply cycling off and on.

[phlash]

Ok, so, I took it into the shop. Guy said 4 of the output transistors on 1 channel are shorted out. Supposed to take between a week and 10 days to get it back. Total price is $188.00 including diagnostic and labor and parts. How fair is this? I would assume thats not too shabby.

[phlash]

Which is a pretty consistent description of a power supply cycling off and on.

This guy....this guys good...ayyyyyyyy....this guy... thanks

[phlash]

For those of you who need parts, or advice Rick @ Harman (soundcraft) is SUPER nice to deal with and works on these all the time. I called him regarding trying to get parts. The output transistors were 20 bucks apiece. The guy at the shop I took it to, found them apparently for 15. So, just to give whoever reads this an idea of what the costs associated are. Rick also said it may be a power supply problem in addition to the transistors, I suppose when the shop replaces them we shall find out and if it is the power supply on that board, I am better off buying a new board, and scrapping this one due to the cost of the digital power supply.

Mike