Hi rodner,
What I would do is identify all the trip inputs to the protection circuit and measure each to see where the source of the trip is coming from. Where you have signals wire or'ed with diodes, just look for the forward biased one.
So far I'm working off memory. I would have to get into the schematic for any specific advice. But the point remains, if the protection circuit is active, assume there is a reason for it. That would be the only assumption you make. Prove everything from here on in with specific measurements. The only way you can get stuck at this point is by assuming something is true without verifying it. Happens to the best of technicians, and we ought to know better.
-Chris
What I would do is identify all the trip inputs to the protection circuit and measure each to see where the source of the trip is coming from. Where you have signals wire or'ed with diodes, just look for the forward biased one.
So far I'm working off memory. I would have to get into the schematic for any specific advice. But the point remains, if the protection circuit is active, assume there is a reason for it. That would be the only assumption you make. Prove everything from here on in with specific measurements. The only way you can get stuck at this point is by assuming something is true without verifying it. Happens to the best of technicians, and we ought to know better.
-Chris
I've check for protection faults and haven't found anything. The relays are being engaged. The signal to the relay is clean. What's coming out of the relay in distorted and low amplitude.
In that case the contacts are badly burned.
After you replace those relays, a real PITA, make sure you turn the volume down before turning it on or off. The relays will last longer. If it goes into protect during loud music, it can burn the contacts right then. These sets are capable of dumping large amounts of current.
Let us know what you think of it after the relays are done.
-Chris
After you replace those relays, a real PITA, make sure you turn the volume down before turning it on or off. The relays will last longer. If it goes into protect during loud music, it can burn the contacts right then. These sets are capable of dumping large amounts of current.
Let us know what you think of it after the relays are done.
-Chris
Relays are done and it's been playing for about 2 hours. It sounds great! Very powerful, very nice sound!
Got another one of these. Does anyone have the values for the power resistors? This one cooked them and I can't find it in the manual.
Okay, the resistors are there in the manual. Find them on the component layout diagram, then find the resistor numbers in the schematic, or the parts list. That should do you.
I'm up to my eyeballs in work, otherwise there would be time to search the manual myself.
-Chris
I'm up to my eyeballs in work, otherwise there would be time to search the manual myself.
-Chris
Hi Craig,
Yes, power supply. There is a group of four, 3 watt metal oxide resistors that run hot. They usually have cooked solder joints, but rarely need replacement.
-Chris
Yes, power supply. There is a group of four, 3 watt metal oxide resistors that run hot. They usually have cooked solder joints, but rarely need replacement.
-Chris
Hello Chris,
That's what I thought he was referring to but had to make sure.
R655 680 Ohm 2W MO
R656 62 Ohm 2W MO
R657 820 Ohm 2W MO
R658 68 Ohm 2W MO
If replacing I would bump them to 3W. The schematic has 100 Ohm for R656 and R658 but are crossed out, the parts list has the current values.
Craug
That's what I thought he was referring to but had to make sure.
R655 680 Ohm 2W MO
R656 62 Ohm 2W MO
R657 820 Ohm 2W MO
R658 68 Ohm 2W MO
If replacing I would bump them to 3W. The schematic has 100 Ohm for R656 and R658 but are crossed out, the parts list has the current values.
Craug
Hi Craig,
Yup, those values look right. 3W is all I'll use for those as replacements.
Hi rodner,
Desolder one end first and measure them. Use fresh solder if they test okay and desolder the other side and use fresh solder again. Adding new solder to the old crystallized joints will not be as reliable as all new solder. It helps to clean the leads on the resistors as well.
-Chris
Yup, those values look right. 3W is all I'll use for those as replacements.
Hi rodner,
Desolder one end first and measure them. Use fresh solder if they test okay and desolder the other side and use fresh solder again. Adding new solder to the old crystallized joints will not be as reliable as all new solder. It helps to clean the leads on the resistors as well.
-Chris
Hi Guys, been a while since anyone wrote anything on this thread, but I am having the same problem with my MRX 130 after enjoying it for a few months. I am less electronics savvy than most on here. Anyone have a photo they could take showing what parts you replaced to fix yours, assuming it's the same problem?
No!
Stop right there!!!
Carver products are not normal and you can completely destroy one without even trying. Believe me, I have seen this time and time again. Even "techs" do a good job of wrecking these products. Besides, many faults can cause the same issues. Additionally, most techs can't even clean a control properly - believe it or not.
I'm not trying to be hard on you. These days I see service people destroying simple equipment doing basic service steps. Add to that mix a complicated product like a Carver (and a few other brands) and you are generally left with much more damage. These Carver units have voltage sensing and feedback to set the main rail voltages. They monitor several supplies, not just one point. If anything goes wrong here, it will either shut down (you hope), or the voltage may go sky high and destroy lots of stuff. That and supply voltages are pretty high in some of these.
The least expensive option for you is to locate a person trained (by Carver) on these products and get that receiver to them. I'm in Canada and was the Canadian factory warranty shop owner. We had a few other warranty shops across Canada. If you are in the 'States there is a shop that was the service department in Carver. Use one of these - please! DO NOT take it to your local "expert" or service guru who is sure he (or she) can fix it (or anything).
You have no training at all. I have been doing this for over 45 years and things that seem obvious to me and don't need to be mentioned will be unknown to you. So if someone tried to guide you, there are a lot of assumptions we make as to what you should know. I have trained many technicians over the years who had formal electronic training to build on. Very few of those people could deal with a Carver, I tried to teach them and some got it. Most didn't.
If you are determined to do this yourself, or have a friend help, just pour gasoline / petrol over the unit, light it up and enjoy the show.
Stop right there!!!
Carver products are not normal and you can completely destroy one without even trying. Believe me, I have seen this time and time again. Even "techs" do a good job of wrecking these products. Besides, many faults can cause the same issues. Additionally, most techs can't even clean a control properly - believe it or not.
I'm not trying to be hard on you. These days I see service people destroying simple equipment doing basic service steps. Add to that mix a complicated product like a Carver (and a few other brands) and you are generally left with much more damage. These Carver units have voltage sensing and feedback to set the main rail voltages. They monitor several supplies, not just one point. If anything goes wrong here, it will either shut down (you hope), or the voltage may go sky high and destroy lots of stuff. That and supply voltages are pretty high in some of these.
The least expensive option for you is to locate a person trained (by Carver) on these products and get that receiver to them. I'm in Canada and was the Canadian factory warranty shop owner. We had a few other warranty shops across Canada. If you are in the 'States there is a shop that was the service department in Carver. Use one of these - please! DO NOT take it to your local "expert" or service guru who is sure he (or she) can fix it (or anything).
You have no training at all. I have been doing this for over 45 years and things that seem obvious to me and don't need to be mentioned will be unknown to you. So if someone tried to guide you, there are a lot of assumptions we make as to what you should know. I have trained many technicians over the years who had formal electronic training to build on. Very few of those people could deal with a Carver, I tried to teach them and some got it. Most didn't.
If you are determined to do this yourself, or have a friend help, just pour gasoline / petrol over the unit, light it up and enjoy the show.