I need help substituting the output FETs on a K2 with Fairchild FQP16N25C as the originals have been discontinued. There was a "compensation mod" that needed to be done on the main board. Anybody have a copy? Maxxarcade are you out there! Tonino?
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Crown has changed a lot since they closed the Elkhart service facility over a year ago, No service documentation is available any longer, they tell me its all considered "intellectual property" now. Won't let you speak with Techs anymore either. You have to be an authorized service center now. I had a feeling the Samsung purchase of Harmon several years ago would not be good news.
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You can't do Make America Great Again like this. Traditional American factories shut down and the staff laid off. there were probably very incompetent lazy managers and technican at Crown for many years who were unable to bring competitive products onto the market at attractive prices.
> "No service documentation is available any longer, they tell me its all considered "intellectual
> property"
You can lol, they no have anymore intellectual property, it's just a trading btand selling company
how many others from the past
Its same like German Brands who were large at the same time and had an excellent reputation.
The Japanese brands have just followed the same path as the former German brands in recent years
JVC - TOSHIBA - AKAI have closed their Japanese factories, sell their name and reputation for every third party TV and audio equipment manufacturer making money by licensing every device they sell
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cardinal PM me with a real e-mail address and I'l send you service manual and schematics.
NMOS; I would be very carefull with substituting the old FQP16N25C wit something like IPI320N20N3 G.
These are hyper fast devices and at least I have personally had problems making them work properly. (have new design ongoing which will hopefully be able to use these devices .... know you have a nice working design so I need to make it work 😉 )
FQP16N25C are quite/very slow fets, and the K2 design, I think is not made for a fast device ... e.g. it does not use snubbers or any other damping of ringing.
Look at IR's fets and find something similar. .... not saying it will not work, but I would chose something a little less challenging.
The K2 uses +-103 Vdc so you need 250V fets.
Also it does not use external flywheel diodes so the fest need low trr .... the FQP16N25C has 110 nS, which is quite good.
The FQP16N25C has very low ciss = 830 nC, and therefore requires very little gate current. On the other hand the K2 uses MC34151 as drivers which should be ok for driving up to more than 3000 nC (but each driver has 2 x fet in parallel) ... so be careful in this selection as well.
... are you sure it is only the fets which are gone??
/Baldin
NMOS; I would be very carefull with substituting the old FQP16N25C wit something like IPI320N20N3 G.
These are hyper fast devices and at least I have personally had problems making them work properly. (have new design ongoing which will hopefully be able to use these devices .... know you have a nice working design so I need to make it work 😉 )
FQP16N25C are quite/very slow fets, and the K2 design, I think is not made for a fast device ... e.g. it does not use snubbers or any other damping of ringing.
Look at IR's fets and find something similar. .... not saying it will not work, but I would chose something a little less challenging.
The K2 uses +-103 Vdc so you need 250V fets.
Also it does not use external flywheel diodes so the fest need low trr .... the FQP16N25C has 110 nS, which is quite good.
The FQP16N25C has very low ciss = 830 nC, and therefore requires very little gate current. On the other hand the K2 uses MC34151 as drivers which should be ok for driving up to more than 3000 nC (but each driver has 2 x fet in parallel) ... so be careful in this selection as well.
... are you sure it is only the fets which are gone??
/Baldin
Crown K1 amplifier repair - YouTube
.... could it be something else than the fets??
Have been investigating a little. Not that easy to find a suitable substitute, 250V, trr around 100nS, >16A, TO220
Most higher than 200 V fets has more than 200 nS trr, and would need a parallel flywheel diode.
As the board and heatsink has place for 4 fets, maybe one way could be to use 2x IRFB4229 and a suitable TO220 diode connected to the fet wia short wires (and not directly connected to the pcb).
Think a pair of IRFB4229 would be fine for this power .... it will mean 4 in all per chanel (in the special BCA) connection .....
.... could it be something else than the fets??
Have been investigating a little. Not that easy to find a suitable substitute, 250V, trr around 100nS, >16A, TO220
Most higher than 200 V fets has more than 200 nS trr, and would need a parallel flywheel diode.
As the board and heatsink has place for 4 fets, maybe one way could be to use 2x IRFB4229 and a suitable TO220 diode connected to the fet wia short wires (and not directly connected to the pcb).
Think a pair of IRFB4229 would be fine for this power .... it will mean 4 in all per chanel (in the special BCA) connection .....
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The special BCA connection doesn’t use the body diodes inside the FETs. The return energy is sent through a pair of fast diodes on alternate sides of the bridge. Fall times are far less important in this topology as well, and it’s not subject to all the ringing that plagues traditional class D. Cross conduction is actually intentional, as the current is controlled by the current balancing inductor. FET substitution can be based on just voltage and current rating, and whether or not the driver can drive the input capacitance.
Mosfet types which are available *today* seem to change almost monthly these days. I’m sort of surprised the IRFB/IRFS4227 has lasted as long as they have since they are written into just about everybody’s class D amp BOM (which would cost a collective fortune to change industry wide - they always seem to delight in making everyone waste money).
Mosfet types which are available *today* seem to change almost monthly these days. I’m sort of surprised the IRFB/IRFS4227 has lasted as long as they have since they are written into just about everybody’s class D amp BOM (which would cost a collective fortune to change industry wide - they always seem to delight in making everyone waste money).
Hi wg_ski
You are right, I jumped to conclusions too fast ... BCA has some differences to "normal" class d, but I think also a lot of features in common.
You are right the diodes does act as free whiling diodes, and should make the internal diode much less critical or not important.
The MC34151 drivers can sink and source 1.5 A
You are right, I jumped to conclusions too fast ... BCA has some differences to "normal" class d, but I think also a lot of features in common.
You are right the diodes does act as free whiling diodes, and should make the internal diode much less critical or not important.
The MC34151 drivers can sink and source 1.5 A
We using IRFP4227 for Kilowatt Fullbridge UcD its a great mosfet, hard to beat
IRFB4137 should solve problem as substitute in Crown K2
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