Thanks for the reply. I have both a pro 9200 and cc4000 when powered up they will go active but the clip LEDs stay lit and this is without signal. They are supposed to go out once amp goes active. Can't seem to figure this out. The amp works and outputs audio as normal. Just trying to figure out what is causing the clip LEDs to stay lit
no presence of even a small amount of DC at the output? i can't say for sure with these models but with older models the sense and metering circuit where quite sensitive. do they behave the same way with inputs and loads disconnected?
There is no dc present at output. If signal and load are connected the amp plays normal. As though something is triggering the clip led to stay on . They are supposed to turn of when the amp goes active but they stay lit.
when you checked for DC at the output there was no load connected correct (as in no speaker hooked up)?
and do you have an oscilloscope available? i'd be checking supply stability to ensure it isn't oscillating at a high frequency(bad filters) that can trigger the meter circuit into a latch state.
how old is the amp? and has it had a hard life?
and do you have an oscilloscope available? i'd be checking supply stability to ensure it isn't oscillating at a high frequency(bad filters) that can trigger the meter circuit into a latch state.
how old is the amp? and has it had a hard life?
Hey Turk thanks for the reply but good news I found the problem three caps on the clip circuit were leaky changed them and it's all good now. Thanks very much for your time and troubleshooting.
Biggest problem with Crest amplifiers in general - the electrolytics in all the support circuitry. The audio circuity is bulletproof, but the relay drivers, fan speed control, clip limiters, etc. all rely on 20 cent caps to stay working properly. If you get one, you just change out all those caps and save yourself headaches later. When I got my used Crests (CA18's) the company said they have their techs change out all those problem caps every couple years to prevent field failures. Looking at the schematics, I can see why.
Hey guys,
Need some assistance with another crest pro9200 that I got. On checking the unit there is no power. the unit apparently was plugged into 220v while the 120v link wire was left in place and there was arcing the bottomofthe board in the area where the thermistor andrelay are located.i checked all major components and all see to be fine. There aren't burnt copper traces etc. Currently if Ipower up using a light bulb on line the bulb glows bright and dims which shows no major shorts. The Acl leds should come on after the initial turn on but no go. R1 gets really hot and q9 and U2 also gets really hot! I changed out these parts also u3 , u4, u11, u9and u12, but still no go. At b4 I am getting only 18v whereas the diagram says it should be 28v?
Could you guys please help me troubleshoot this . Would greatly appreciate it.
Thanks in advance.
Need some assistance with another crest pro9200 that I got. On checking the unit there is no power. the unit apparently was plugged into 220v while the 120v link wire was left in place and there was arcing the bottomofthe board in the area where the thermistor andrelay are located.i checked all major components and all see to be fine. There aren't burnt copper traces etc. Currently if Ipower up using a light bulb on line the bulb glows bright and dims which shows no major shorts. The Acl leds should come on after the initial turn on but no go. R1 gets really hot and q9 and U2 also gets really hot! I changed out these parts also u3 , u4, u11, u9and u12, but still no go. At b4 I am getting only 18v whereas the diagram says it should be 28v?
Could you guys please help me troubleshoot this . Would greatly appreciate it.
Thanks in advance.
Crest CA6 - Fixed !!
Thanks guys for this thread - just helped me fix a Crest CA6 that I picked up on Craigslist today for $100.00 !!
The left-hand channel was in protect mode. By some dubious swapping of output and preamp modules, I was able to determine that it was the left-hand preamp which was causing the problem. So after reading this thread, I swapped out all the large caps on the preamp board - even though their values read ok on my meter and bingo !! problem solved. No more protect mode. Now I have a working 2-channel amp. The caps I put in just were what I could find in my spares box - but they will do for now until I order a set of brand new ones from Mouser. I just needed this for my backup amp for a DJ gig on Saturday.
Thanks again !!
Thanks guys for this thread - just helped me fix a Crest CA6 that I picked up on Craigslist today for $100.00 !!
The left-hand channel was in protect mode. By some dubious swapping of output and preamp modules, I was able to determine that it was the left-hand preamp which was causing the problem. So after reading this thread, I swapped out all the large caps on the preamp board - even though their values read ok on my meter and bingo !! problem solved. No more protect mode. Now I have a working 2-channel amp. The caps I put in just were what I could find in my spares box - but they will do for now until I order a set of brand new ones from Mouser. I just needed this for my backup amp for a DJ gig on Saturday.
Thanks again !!
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