I just purchased a Carver 2000 magnetic field receiver.
it works fine until the volume control hits about 10/11 o'clock, then protection cuts off the relays for a few seconds while I lower the volume setting and then its fine until I take it back to 10/11 oclock again
I opened it up and visually it looks fine.
I measured the four largest caps and they seem fine with a standard cap meter
I set the voltage adjust to 69V
then I went to set the idling voltage and it acted weird.
I measured 0 volts on both channels instead of 4.5 but adjusting the two trimmers did absolutely nothing.
does anyone have any suggestions ?
thanks
it works fine until the volume control hits about 10/11 o'clock, then protection cuts off the relays for a few seconds while I lower the volume setting and then its fine until I take it back to 10/11 oclock again
I opened it up and visually it looks fine.
I measured the four largest caps and they seem fine with a standard cap meter
I set the voltage adjust to 69V
then I went to set the idling voltage and it acted weird.
I measured 0 volts on both channels instead of 4.5 but adjusting the two trimmers did absolutely nothing.
does anyone have any suggestions ?
thanks
Dried up mains caps usually cause low power out, not protection relay cutout.
I have a schematic for a Carver 1.5k and it is a complex unit with two sets of output voltages and output transistors that amp in stages. If you have found a schematic diagram of the 2000, more power to you. Post it here if you want more help.
If you are not experienced at this, I suggest you try something else. +-76 v rails are not to be trifled with. I decided not to buy the Carver 1.5k, however cheap it was. Other amps are much simpler.
First check is usually short the inputs. Then see if amp section has DC voltage over 200 mv at the series to speaker coil, or at the input of the disconnect relay. This is also junction of emitter resistors of the two lower voltage output transistors.
Warning - use one hand at a time probing units with power on or after power has been applied and before caps have discharged. >25 v from one hand to the other can stop your heart. Use alligator clip lead on DVM negative lead to analog ground (speaker return). Wear no jewelry on hands arms or neck. 1 v at high enough current through a ring can burn your flesh to charcoal. Wear safety glasses, solder can splash in the eye. Also damaged parts can explode. I bounced some MJ15024/5 tops of the ceiling on an 85 v rail amp.
If voltage to input of disconnect of relay is above 200 mv, likely one or more output transistors has failed. Failed OT can allow high voltage out the base line and blow up drivers, predrivers, input op amps, VI limiters, etc etc. One reason high $ amps get sold off.
Any work on 2000 W amp needs to be powered through an AC current limiter. Some people use 100 W incandescent bulb in series, but on my 1.3 kw amp I found the op amps wouldn't power up with that. I ended up putting a 1200 w room heater element in series with the AC input to the amp. This stopped the explosions of damaged output transistors. Your results may vary.
I have a schematic for a Carver 1.5k and it is a complex unit with two sets of output voltages and output transistors that amp in stages. If you have found a schematic diagram of the 2000, more power to you. Post it here if you want more help.
If you are not experienced at this, I suggest you try something else. +-76 v rails are not to be trifled with. I decided not to buy the Carver 1.5k, however cheap it was. Other amps are much simpler.
First check is usually short the inputs. Then see if amp section has DC voltage over 200 mv at the series to speaker coil, or at the input of the disconnect relay. This is also junction of emitter resistors of the two lower voltage output transistors.
Warning - use one hand at a time probing units with power on or after power has been applied and before caps have discharged. >25 v from one hand to the other can stop your heart. Use alligator clip lead on DVM negative lead to analog ground (speaker return). Wear no jewelry on hands arms or neck. 1 v at high enough current through a ring can burn your flesh to charcoal. Wear safety glasses, solder can splash in the eye. Also damaged parts can explode. I bounced some MJ15024/5 tops of the ceiling on an 85 v rail amp.
If voltage to input of disconnect of relay is above 200 mv, likely one or more output transistors has failed. Failed OT can allow high voltage out the base line and blow up drivers, predrivers, input op amps, VI limiters, etc etc. One reason high $ amps get sold off.
Any work on 2000 W amp needs to be powered through an AC current limiter. Some people use 100 W incandescent bulb in series, but on my 1.3 kw amp I found the op amps wouldn't power up with that. I ended up putting a 1200 w room heater element in series with the AC input to the amp. This stopped the explosions of damaged output transistors. Your results may vary.
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I do have a schematic but I doubt it would be readable if I post it. is is available free from a multitude of sites on the internet
all four main PS caps seem to test fine
it seems the problem is when the amp is switching between the low voltage and high voltage rail, that seems to imply a problem with the 69V PS or with a component involved in the switching.
I am hoping someone experienced with carver amp technology has some wisdom to share.
all four main PS caps seem to test fine
it seems the problem is when the amp is switching between the low voltage and high voltage rail, that seems to imply a problem with the 69V PS or with a component involved in the switching.
I am hoping someone experienced with carver amp technology has some wisdom to share.
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You seem pretty green to be working on this. The shop near me that repairs PA & instrument amps and resells them, even SWTC tigers, sells off the Carvers broken. Tell you anything? Notice in 42 hours nobody that has fixed one has posted?
"four capacitors test fine" is a gloss of reality. The rail capacitors that were limiting a 32 year old 100 watt amp to 2 watts were reading 8% high on a capacitance meter. The ESR was about 2.5 times what it was supposed to be.
What really matters is what the rail voltages are when you are trying to draw significant watts. And you can't measure those with a 4 second averaging DVM while drawing wattage, either. You need a scope or a quick reading analog VOM. If rail voltages take a dive when you turn up watts, there you are. Capacitors are not necessarily the problem, but the first check necessary after you have checked the output for DC voltage. Four rail voltages to check, then a check of both op amp voltages when the fault is occuring.
"four capacitors test fine" is a gloss of reality. The rail capacitors that were limiting a 32 year old 100 watt amp to 2 watts were reading 8% high on a capacitance meter. The ESR was about 2.5 times what it was supposed to be.
What really matters is what the rail voltages are when you are trying to draw significant watts. And you can't measure those with a 4 second averaging DVM while drawing wattage, either. You need a scope or a quick reading analog VOM. If rail voltages take a dive when you turn up watts, there you are. Capacitors are not necessarily the problem, but the first check necessary after you have checked the output for DC voltage. Four rail voltages to check, then a check of both op amp voltages when the fault is occuring.
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You may want to take your problem to;
Carver audio forum, free Carver manuals, Carver audio information, Carver audio repair, Carver specifications, Carver modification, Carver upgrade, Carver amplifiers, Carver amplifier, Carver amp, Carver home audio, Carver hifi
There are several good people there that have experience working on the Carver receivers.
Carver audio forum, free Carver manuals, Carver audio information, Carver audio repair, Carver specifications, Carver modification, Carver upgrade, Carver amplifiers, Carver amplifier, Carver amp, Carver home audio, Carver hifi
There are several good people there that have experience working on the Carver receivers.
thank you for your response, I fear you are confusing Carver stereo equipment with Carvin PA and instrument amps. They are not the same
Thank you for your response, I posted there a week ago and the only advice I got was to check DC offset (which is fine)
I went back and found your thread. You may have to send a pm to someone like kve777 or dennismiller55 or RobertR to get them active in your repair. I know they have all worked on the receivers.
If you've done a search here, you will find a few threads about carvers.
Carvers are a nightmare.
Even seasoned pros that worked on them don't want to know them.
Carvers are a nightmare.
Even seasoned pros that worked on them don't want to know them.