Working on Carver C4000 and could use some help
- Thread starter Dutch54
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- Jan 14, 2011
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- 74,883
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- Gillette, Wyo.
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- Halfbiass...Electron Herder and Backass Woof
Those resistors are in parallel with the regulators. There is a downstream fault. My guess is either a chip or electrolytic cap(s) in backwards. There is potential danger if it's a cap as it could become a projectile if allowed to fail. To troubleshoot use the nose and index finger to find something getting hot. I
The Power Supplies on the C-4000 are crap and that is why me and Glen used the Power Supply Boards we had ginned up. When installed, they keep the PS Voltage spot on at 12VDC. Did you go around the boards and check the 12VDC (+ and -)? We've seen them down near 8 volts or less. We changed out all the RC4136 IC's to new ones (old and noisy) and spliced in the power supply. The Carver PS is rudimentary at best. Glen also adds bypass caps to the RC 4136 chips.
Take it off the DBT and shoot it with the Laser Thermometer. Your DBT may also be messin with the regulators. Preamps don't generally need to be on a DBT, yer not messin with high rail voltages and if you do use A DBT, what size bulb are you using? Did you see all the threads we did on the C-4000???? With the C-4000 having a 250ma fuse in it, a dbt is a waste.
The rear amp is also a problem spot. It's full of obsolete parts and it takes a LOT of work to get them rebuilt. Do some browsing, there is a bunch of info available (either here or the Carver Site).
Here is the PS we use.
OH,As a side note, I have seen the stock power supply board installed one pin off causing that same issue.
Take it off the DBT and shoot it with the Laser Thermometer. Your DBT may also be messin with the regulators. Preamps don't generally need to be on a DBT, yer not messin with high rail voltages and if you do use A DBT, what size bulb are you using? Did you see all the threads we did on the C-4000???? With the C-4000 having a 250ma fuse in it, a dbt is a waste.
The rear amp is also a problem spot. It's full of obsolete parts and it takes a LOT of work to get them rebuilt. Do some browsing, there is a bunch of info available (either here or the Carver Site).
Here is the PS we use.
OH,As a side note, I have seen the stock power supply board installed one pin off causing that same issue.
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DON'T cut any traces. Troubleshoot the thing. Get a laser Thermometer and check how hot the resistors are getting. they are designed to withstand finger burning amounts of heat. Some will handle 150C and that will take the fingerprints right off you finger (And get off the Dim Bulb). If they haven't smoked the board under them, like a 400/700 PL14-20, don't worry about it.
DON'T cut any traces. Troubleshoot the thing. Get a laser Thermometer and check how hot the resistors are getting. they are designed to withstand finger burning amounts of heat. Some will handle 150C and that will take the fingerprints right off you finger (And get off the Dim Bulb). If they haven't smoked the board under them, like a 400/700 PL14-20, don't worry about it.