Blitz said:
I will simply repeat one of Mr. Pass's oft heard responses, something like "because I (Pass) have a lot of them".
I believe you see resistors of that ilk crop up in many/most First Watt/Pass DIY designs. My opinion (worth not much) is that Mr. Pass is the master (or rather Master) of finding parts that work well without having to go "boutique" on us. So thanks for that Mr. Pass.
Ryan
If you want to use Caddock instead of the Panasonic 3W resistors, look no further than the MP930. For that matter, they have other resistors that will do as well, but I've sorta standardized on the MP930 and tend to keep a few on hand rather than stock all the other models between the MK132 and the MP930.
Grey
Grey
luvdunhill said:
I tend to think that playing with bypasses will be more fruitful that then Black Gates. I'm assuming you're using Peter's boards, in which case which models have you found that will fit?
Also, I'd like to see some pictures
I will make some pictures next, I used basically the enclosures of http://www.hifi-2000.com/ which you see in the upper left corner...
HAs anyone made a simulation model of the F4 ? How big does the C1 and C2 really have to be ? Maybe a foil-cap is even possible ?
gentlemen-i have my f4 ready to turn on for the first time-this is my first solid state amp.the power supply checked out fine,P2 is in the center position P1 is at max, 5k.---at turn on when i adjust P2 where do i measure the dc offset? at the speaker teminals? adjusting P1 sets the bias but where do i measure it? and what is the normal bias--i have read the previous posts but need a little handholding--thanks for any help you may give me--i'll leave it shut off until i get clarification-mark
i fired up my F4 using a variac and didn't get very far- i blew the 3amp fuse immediately--i am using peter's boards and have 6-32 standoffs and using silpads-i sanded the heatsink with 600 sandpaperand the mosfets so everything is smooth--i was wondering if maybe the standoffs might be getting close to a source resistor so i uninstalled both boards and put cardboard behind them to insulate them and fired it back up using a 1.25 amp fast blo--i took it up to 120v no problem--put my meter probes on either side of a silpad and measured 100 ohms!any one else have this problem?? going to order plastic standoffs and would like to order mica insulators where can you buy them for the mosfets? i looked at some to-220 micas but some hole is under the metal no matter which hole i use-do you double the mica up so the holes don''t line up??thanks for your help-mark
nelson-you mean just use the mica(you wrote silpad) holes and all-just snip it to size?----- and i used blunt aligator clips and put the silpad between them-----just realized i can't use nylon standoffs because of the heat-will " machine "the metal ones to make them slightly smaller in diameter
The Mica is used for electrical isolation. The thermal paste is for the heat transfer. The extra holes and size of the mica won't make a big difference in the end. Use what you've got and just make sure it has enough thermal paste to have good thermal conductivity.
Don't use 2 pieces of mica. Even though there are extra holes, they will still isolate your fets electrically.
Don't use 2 pieces of mica. Even though there are extra holes, they will still isolate your fets electrically.
Hard tellin not knowin.
I would take everything off the heatsink and make sure there aren't any little metal slivers causing a short and remount things and hope for the best. I shorted a fet to ground and blew the fuse on mine. No damage done.
Also are you using shoulder washers to keep the mounting screws from gounding the fets? Just trying to eliminate the easy stuff.
I would take everything off the heatsink and make sure there aren't any little metal slivers causing a short and remount things and hope for the best. I shorted a fet to ground and blew the fuse on mine. No damage done.
Also are you using shoulder washers to keep the mounting screws from gounding the fets? Just trying to eliminate the easy stuff.
the fets have an insulated top and through hole no need for a shoulder washer--i took them off of the heatsinks and was able to set p1 to get 100mv and they heated up nicely--waiting for ups to deliver my TO3 mica insulators-i practiced and can drill out one of the small holes to accept 6-32 hardware and trim it to fit the fets with everything covered!