I intended to do the right thing by replacing the old power supply caps in my model 3 amp. What I found were some caps that are much bigger in value and size, and voltage. The originals are 24,000 with a 60 volt surge rating. The new ones are 37,000 with a rating of 100V. After replacing the caps, the amp immediately blew the 8 amp main fuse. I then put a 6 amp current limiter in the incoming AC line after the fuse. It still blows the main fuse. I am thinking that I would be better off just getting 24,000 uf caps of the same voltage rating and calling it good. Any thoughts?
Unless your new capacitors were installed incorrectly (or are bogus), they are not what is blowing the line fuse.
"Unless your new capacitors were installed incorrectly (or are bogus), they are not what is blowing the line fuse."
I do agree with your assessment. Think that I might take a second look. Just didn't think that there would be a huge increase in inrush current. Thanks for the thought.
I do agree with your assessment. Think that I might take a second look. Just didn't think that there would be a huge increase in inrush current. Thanks for the thought.
recheck polarity of those caps
I hope you took some pictures , prior to replacing caps , as guide
I hope you took some pictures , prior to replacing caps , as guide
It looks like the caps in the rear of the photo are installed with the wrong polarity as the blue wire is connected to the positive cap terminal - I would have thought the blue wire would be the negative supply voltage.
Gary..
Gary..
AHA! Gary, let me double check a photo of the power supply that I say elsewhere. I think that you are correct sir. This does not really surprise me as I tend to do mirror image work usually, but this one doesn't work that way.
Gary,
I reversed the polarity (just like Kirk did on Star Trek against Scotty's wish), and it works. "My Creature Has LIFE! The transistors are running about 113 F on both sides. Now, just to check, the current limiting device is cooking at 260 F. That sounds a little warm to me. It is rated at 6 amps. Should get a bigger one or just take it out all together?
I reversed the polarity (just like Kirk did on Star Trek against Scotty's wish), and it works. "My Creature Has LIFE! The transistors are running about 113 F on both sides. Now, just to check, the current limiting device is cooking at 260 F. That sounds a little warm to me. It is rated at 6 amps. Should get a bigger one or just take it out all together?
I think Nelson likes to run heatsink temps for class A amps at around 50 to 55 deg c so 113 F (45 deg C)is a bit low, Check the biasing as per instructions and maybe the current limiting device is faulty or the wrong type. I assume you have all the schematics and biasing instructions for this amp.
Gary,
Thanks for the info. The amp is actually running class A/B at 200 WPC, so I am thinking that the temp may be good. As far as schematics/service manual, I would really like to find either! If you know where I could get my hands on such, let me know.
Maybe I will try another step up for a current limiter, like 8 amp. or so. If that doesn't work, I may just take it out of circuit.
Greg
Thanks for the info. The amp is actually running class A/B at 200 WPC, so I am thinking that the temp may be good. As far as schematics/service manual, I would really like to find either! If you know where I could get my hands on such, let me know.
Maybe I will try another step up for a current limiter, like 8 amp. or so. If that doesn't work, I may just take it out of circuit.
Greg
Forte Model 3 conversion to Model 1a
I have a Forte Model 1a and Model 3. I'd like to convert the Model 3 to be identical to the Model 1a, Class A, 50wpc @ 8ohm. Can anyone offer me some help in doing this conversion? I'm told the two amps are identical except for power supply ground plane and bias setting.
I have a Forte Model 1a and Model 3. I'd like to convert the Model 3 to be identical to the Model 1a, Class A, 50wpc @ 8ohm. Can anyone offer me some help in doing this conversion? I'm told the two amps are identical except for power supply ground plane and bias setting.
you can give us pictures of both , to decipher
probably easier than rummage through old threads to find info
probably easier than rummage through old threads to find info
Forte Model 3 conversion to Model 1a
I have several photos in a folder on my desktop. How do I attach or post them to this thread? Thanks for your assistance!
I have several photos in a folder on my desktop. How do I attach or post them to this thread? Thanks for your assistance!
left corner bellow last post- post reply-write - scroll down - manage attachments-browse- attach what you have to - upload - close this window-submit reply
simple , isn't it :
simple , isn't it :