I am the proud new owner of a Carver PM-900 amp that will serve duties powering a passive subwoofer that I am building.
The amp seems to operate perfeclty so far but I want to make a project out of this too so I thought it would be a good learning expirence to replace some of the capacitors as I know they have a finite life span.
I need to replace one capacitor for sure as it's top is domed. I beleive it is in the regulator circuit (or that's what it looks like from the diagram in the manual).
Then there are the 2 large caps. by the power supply. They are 9000uF 100V units. I have only seen a few with that measurement avail. online.
Can I use a 10,000uF cap. ? What effect does that have on the amplifier?
Now that I type this I realize that I'm less qualified to make these "decisions" than I thought, but I'm handy with a soldering iron!
The amp seems to operate perfeclty so far but I want to make a project out of this too so I thought it would be a good learning expirence to replace some of the capacitors as I know they have a finite life span.
I need to replace one capacitor for sure as it's top is domed. I beleive it is in the regulator circuit (or that's what it looks like from the diagram in the manual).
Then there are the 2 large caps. by the power supply. They are 9000uF 100V units. I have only seen a few with that measurement avail. online.
Can I use a 10,000uF cap. ? What effect does that have on the amplifier?
Now that I type this I realize that I'm less qualified to make these "decisions" than I thought, but I'm handy with a soldering iron!
Oh here's a picture too.
An externally hosted image should be here but it was not working when we last tested it.
Yes you can go to the 10,000uF capacitors. I would make sure that they are the same physical dimensions, since it looks like a very tight location. More capacitance (uF) simply means more energy stored and available when needed in the case when a capacitor is used in a power supply application. In timing (another DC application) and signal coupling (an AC reactance application) the size (i.e. in uF) is more critical and arbitrary changes in value are not recommended unless you are aware of the consequences those modifications might bring.
Hi Beat_Dominator,
Those caps are perfect. This is a triac regulated supply, so there is a lot of HF transients. You can try bypassing those. May as well change the other, smaller supply caps. There is more than one rail in there (three actually). Therefore you have two more pairs of capacitors to change. These are under harder use and tend to fail sooner than normal.
The only other suggestion I have for you is to make sure your AC connection to the panel is direct with this amp. Other components will not like the current draw off the line when you have it turned up.
-Chris
Those caps are perfect. This is a triac regulated supply, so there is a lot of HF transients. You can try bypassing those. May as well change the other, smaller supply caps. There is more than one rail in there (three actually). Therefore you have two more pairs of capacitors to change. These are under harder use and tend to fail sooner than normal.
The only other suggestion I have for you is to make sure your AC connection to the panel is direct with this amp. Other components will not like the current draw off the line when you have it turned up.
-Chris
Thanks for the input anatech. When I took out one of the 9000uF caps today I noticed one of the diodes on the board next to it is cracked in half . Good thing I pulled that cap though or I might have missed it.
Looking at catalogs I found this:
Cornell Type 500C computer grade cap. # 500C103U100AE2B
It is a 10,000uF unit but is the exact physical size of these 9000 units. Is that a good one to go with?
. Good thing I pulled that cap though or I might have missed it. Looking at catalogs I found this:
Cornell Type 500C computer grade cap. # 500C103U100AE2B
It is a 10,000uF unit but is the exact physical size of these 9000 units. Is that a good one to go with?
Hi Beat_Dominator,
I didn't look the cap up, but that is a good brand. As long as the voltage is the same or higher you will be fine. The 10,000 uF rating is within tolerance of the 9,000 uF cap. Regard it as the same thing.
I can't remember what the temperature rating is on the originals. Make sure you get at least the same rating there too (85°C or 105°C).
Replace the other four supply caps while you are at it. They will have lower voltage ratings. You actually run on the lower rails most of the time, the high rails run earlier parts of the amp circuit.
-Chris
I didn't look the cap up, but that is a good brand. As long as the voltage is the same or higher you will be fine. The 10,000 uF rating is within tolerance of the 9,000 uF cap. Regard it as the same thing.
I can't remember what the temperature rating is on the originals. Make sure you get at least the same rating there too (85°C or 105°C).
Replace the other four supply caps while you are at it. They will have lower voltage ratings. You actually run on the lower rails most of the time, the high rails run earlier parts of the amp circuit.
-Chris
Hi Beat_Dominator,
Don't do that.
Make sure the fan is operating properly. Yes, it goes with the music (you should hear a bunch of them in an amp room, it's amusing).
Who else has an amp that sings with the music? I honestly don't know how you would get more heatsinking attached to begin with.
-Chris
Don't do that.
Make sure the fan is operating properly. Yes, it goes with the music (you should hear a bunch of them in an amp room, it's amusing).
Who else has an amp that sings with the music? I honestly don't know how you would get more heatsinking attached to begin with.
-Chris
But I wanna.
Well the stock unit has like 6 or 8 fins..... I just know that the effective cooling surface area can be improved upon. If worst came to worst I'd at least make it so that the fan could be a very low RPM unit.
On top of that, when I plugged the thing in for the first time the fan was operating at maximum RPM..... so I have doubts that the whole temp. sensing circuit is working.
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