I have a Crown CE 2000 power amplifier with a problem. It goes in and out of protection in both channels with a load connected. With the load disconnected the amp stays out of protection. The load has been checked with an impedance meter and is not the fault.
Any ideas before I rip and tear?
Any ideas before I rip and tear?
Hi burnedfingers,
Have you checked for oscillation? I'm guessing you have ruled out DC offset.
-Chris
Have you checked for oscillation? I'm guessing you have ruled out DC offset.
-Chris
Chris
Thanks for the reply. Yes, I checked the Dc offset and it was normal. I'm not thrilled with Crown amps so you could say I'm trying to get my confidence up to look at it. Can't run a signal thru it because the relays keep going out. Haven't ruled out oscillation as of yet. Heatsinks are cool so that would probably be a positive.
Joe
Thanks for the reply. Yes, I checked the Dc offset and it was normal. I'm not thrilled with Crown amps so you could say I'm trying to get my confidence up to look at it. Can't run a signal thru it because the relays keep going out. Haven't ruled out oscillation as of yet. Heatsinks are cool so that would probably be a positive.
Joe
Hi Joe,
Hang a 'scope on the output before the relay. Watch for oscillation. You may even find that the protection circuit is defective (caps). If this is the case, the supply bypass caps would be good to look at.
-Chris
Hang a 'scope on the output before the relay. Watch for oscillation. You may even find that the protection circuit is defective (caps). If this is the case, the supply bypass caps would be good to look at.
-Chris
And you might contact CRown, not only for service materials/schematics, but also for their support. You may find they are aware of some circumstances where the amp might behave this way and have a fix for it.
I found the problem.
Unfortunately it is a surface mount part and I don't have the equipment to change it so off to Crown it goes.
Thanks for your suggestions and help.
Unfortunately it is a surface mount part and I don't have the equipment to change it so off to Crown it goes.
Thanks for your suggestions and help.
Hi Joe,
You know what I use for smt stuff? A solder pick, solder wick, flux, a wide tip and a magnifying glass. Works well for everything. Just don't sneeze (I have, still haven't found those parts).
I have even had to re and re smt parts, you know the really big chips with leads all the way around? (Korg no have parts yet at the time). And the stuff even worked!!
-Chris
You know what I use for smt stuff? A solder pick, solder wick, flux, a wide tip and a magnifying glass. Works well for everything. Just don't sneeze (I have, still haven't found those parts).
I have even had to re and re smt parts, you know the really big chips with leads all the way around? (Korg no have parts yet at the time). And the stuff even worked!!
-Chris
Chris
Thanks for the reply. I'm sure you are much more apt to have a steady hand than I am. Thirty years ago I would have tried your method. Unfortunately I am a little too unsteady to try it now.
Thanks for the reply. I'm sure you are much more apt to have a steady hand than I am. Thirty years ago I would have tried your method. Unfortunately I am a little too unsteady to try it now.
Thanks Joe,
I'm steady ?? I simply got used to doing it. Practice on some old pcb's some time. Later if you aren't to comfortable with this. If it's any consolation to you, I wasn't very confident when I started either. What the heck.
The worse way to do this is with a tiny tip on your iron. A big screwdriver tip and flux are your friend. I use lacquer thinner to clean up after desoldering and soldering. Some of my work looks factory, some ... well I'd rather not say. The transistors are the hardest to keep lined up. The big chips are easier.
-Chris
I'm steady ?? I simply got used to doing it. Practice on some old pcb's some time. Later if you aren't to comfortable with this. If it's any consolation to you, I wasn't very confident when I started either. What the heck.
The worse way to do this is with a tiny tip on your iron. A big screwdriver tip and flux are your friend. I use lacquer thinner to clean up after desoldering and soldering. Some of my work looks factory, some ... well I'd rather not say. The transistors are the hardest to keep lined up. The big chips are easier.
-Chris
Yikes, I'm fond of thinners but not for cleaning circuit boards.
Metho is the strongest thing I'll use & a mate of mine thinks thats rough.
Metho is the strongest thing I'll use & a mate of mine thinks thats rough.
Hi lowlevel,
Be brave. Just don't use plastic Q-tips (swabs).
I also use Electrowash 2000 with a tooth brush to clean the PCBs. IN all, I wouldn't worry too much about using solvents. Just keep them off certain components. SMT stuff is tough as nails.
-Chris
Be brave. Just don't use plastic Q-tips (swabs).
I also use Electrowash 2000 with a tooth brush to clean the PCBs. IN all, I wouldn't worry too much about using solvents. Just keep them off certain components. SMT stuff is tough as nails.
-Chris
I'm no too precious when cleaning PCB's metho & tooth brush & a good scrub is good for me.
Have found the brushes that come in spray gun cleaning kits are bigger & better though.
Thinners I recon is a bit extreem the nasties in it will probably take the bands of resistors & the print off capacitors
When I was an aprentice we used to refurb telex machines, we would take the pcbs & scrub em down with a nail brush in a troff of detergent & rinse em under the tap.
cheers
Have found the brushes that come in spray gun cleaning kits are bigger & better though.
Thinners I recon is a bit extreem the nasties in it will probably take the bands of resistors & the print off capacitors
When I was an aprentice we used to refurb telex machines, we would take the pcbs & scrub em down with a nail brush in a troff of detergent & rinse em under the tap.
cheers
Hi lowlevel,
Ahhh, I think you misunderstood me. I use solvents only on flux. I will also wash some PCB assy's in mild degergent and let them dry in warm air. Some components are affected badly by chemicals. Old caps washed in a bath of WD-40 means replace all caps (friend of mine found out).
So, your point is well founded & I agree with you.
-Chris
Ahhh, I think you misunderstood me. I use solvents only on flux. I will also wash some PCB assy's in mild degergent and let them dry in warm air. Some components are affected badly by chemicals. Old caps washed in a bath of WD-40 means replace all caps (friend of mine found out).
So, your point is well founded & I agree with you.
-Chris
Sorry to bump an old thread but I am having the same problem with a Crown ce 1000. It also has the parts highlighted in the thumbnail on the first page.
Hi....once I have problem with MA1200 and it was defective input IC.....
Best, Taj
http://www.crownaudio.com/pdf/legacy/130352-1_10-02_ce1-2_serv_revd.pdf
Best, Taj
http://www.crownaudio.com/pdf/legacy/130352-1_10-02_ce1-2_serv_revd.pdf
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