I plan to build BrianGT's LM4780 kit but with a snubberized supply and a 19-0-19 traffo.
Would 2 power supply boards be recommended?
If I use only 1 supply board will a single bridge with 4 MUR860's(because my tranformer is center-tapped) be enough for 90W x 2 into 4 ohm speakers?
Would 2 power supply boards be recommended?
If I use only 1 supply board will a single bridge with 4 MUR860's(because my tranformer is center-tapped) be enough for 90W x 2 into 4 ohm speakers?
blown fuses
I put the 4780 brian gt kit together. The transformer is a plitron with dual secondaries. I left the diode bridge and the amp board together. I got 30 volts dc at v- pg- pg+ v+ The fuses keep blowing; up to 4 amp so far. The chip is mounted directly to the heat sink but the heat sink is isolated from the ground. What size of fuse do I need? Is there a schematic for wiring up the 8 diodes with the red yellow, blue grey secondaries? Red yellow serves one diode rect. and blue grey the other .
I put the 4780 brian gt kit together. The transformer is a plitron with dual secondaries. I left the diode bridge and the amp board together. I got 30 volts dc at v- pg- pg+ v+ The fuses keep blowing; up to 4 amp so far. The chip is mounted directly to the heat sink but the heat sink is isolated from the ground. What size of fuse do I need? Is there a schematic for wiring up the 8 diodes with the red yellow, blue grey secondaries? Red yellow serves one diode rect. and blue grey the other .
Well, 20 years ago Radio Shack carried 'em...
If you can't find them locally, Digikey (www.digikey.ca) has them. Small orders cost $5 to ship, larger orders have free shipping.
Suggested Part Numbers --
3AG (1.25 x .25"):
F329-ND
F332-ND
Metric (5x20mm):
WK2263-ND
WK4860-ND
WK4823-ND
F981-ND
...The ones starting with F are worth about a buck each and are sold in groups of five. The ones starting with W are about fifty cents each and are sold individually. Hint: Order spares.
Wes
If you can't find them locally, Digikey (www.digikey.ca) has them. Small orders cost $5 to ship, larger orders have free shipping.
Suggested Part Numbers --
3AG (1.25 x .25"):
F329-ND
F332-ND
Metric (5x20mm):
WK2263-ND
WK4860-ND
WK4823-ND
F981-ND
...The ones starting with F are worth about a buck each and are sold in groups of five. The ones starting with W are about fifty cents each and are sold individually. Hint: Order spares.
Wes
Thanks for the help. I got some 5amp slo blow at Active Electronics Vancouver. What a hell of a time I had to get it to work!! I finally had to have each primary feeding 1/2 of both sides of the rectifier boards.
The amp sounds great and so quiet, no on off pop, nothing! It is also bringing some new appreciation for some speakers I have.
Just for fun I by-passed one board only with some oil caps. Will plan to listen and evaluate.
The amp sounds great and so quiet, no on off pop, nothing! It is also bringing some new appreciation for some speakers I have.
Just for fun I by-passed one board only with some oil caps. Will plan to listen and evaluate.
Attachments
my LM4780 supply:
here's the schematic:
An externally hosted image should be here but it was not working when we last tested it.
here's the schematic:
An externally hosted image should be here but it was not working when we last tested it.
Good looking power supply! I guess it's up to me tolearn more about power supplies; imho it makes a big difference in the amp performance.
In the interim I did this: added nichicon, g-luxon 4700uf directly to the boards bypassed with .001uf non polar snubber 10r+100nf metal poly cap. Sounds good.
In the interim I did this: added nichicon, g-luxon 4700uf directly to the boards bypassed with .001uf non polar snubber 10r+100nf metal poly cap. Sounds good.
Attachments
One channel did not have the same clarity and bass authority. What I did was use nichicon 4700uf on one side and g-luxon 4700uf on the other all 50 v. I finally tried swithching all I could to try and discover what the difference was. The side with the g-luxon was better all around, Went and changed out the nichicons and put in the g-luxons. Result; these unknown to me luxons are way better imho. I've used nichicons before but never g-luxon.
a nice find,
cheers doggy
a nice find,
cheers doggy
Attachments
jackinnj,jackinnj said:my LM4780 supply:
here's the schematic:
Thats a nice supply.
Now those are snubbers.
Cheers!
Russ
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