B&K 4420 EX4420 and EX422

[usamike10]

Does anyone know what the differences are in these amplifiers? It appears the 4420 is rated at 225w@8 while the other 2 are 200w@8 from what I could find.
Is one better than the other? Or are they the same inside and there just a chronology difference?
I'm considering buying one to power some JBL L7's I just got, but also concerned because there is very little info out there, B&K is no longer in business and I can only find schematics for the EX442.

 

[FootFungus]

The 4420s are the later designs with 4 or 5 pairs of Hitachi TO-3p laterals and internal heatsinks. The EX-442 came in a variety of variations and has external heatsinks, although I had a Sonata version that was the later 4420 design but with JFET inputs. Each model seems to have a multitude of iterations. The later ones are a bit more robustly built.

 

[usamike10]

Thank you for the reply.

 

[Cylontymany]

Is the 4420 a common ground amp?

 

[FootFungus]

Yes, its not bridged. Running Polk SDAs?

 

[Cylontymany]

Yes SDA 2Bs

 

[Onlyanalog65]

I know this is an older thread, but I just picked up a EX4420 Sanota amplifier. I didn't pay much for it, a 150. Bucks, but I was wondering if these could be still required? The amp works fine, the power light was bad, and replaced it with a amber LED, Little bright, buts it fine. The bais seems too be a tad higher on one channel. Any information on how to lift or remove the boards to recap? I also have the matching Pro 10 Sanota preamp that I have been using, also picked up for pretty good price. 350..Any information on it to removed the board for a recap as well.
Any helpful information would be appreciated. Thank you.

 

[painttoad]

It seems that the circuit board needs to be removed from the output transistors themselves.

i think it's like my vmr654. you just need to remove the outputs from the heatsinks.

Does any have any information on recapping one these?

yup.

BE CAREFUL!

the pcbs are dbl sided. the plated thru holes are no bigger than they need to be and are very hard to clear of solder and the back side is super delicate.

do not dwell on the pads with heat. get in. get out. the pads and traces will lift if you look at them funny.

if you are not super efficient at desoldering, i'd recommend paying someone.

 

[Onlyanalog65]

I ended up removing all of the output from the boards, pretty simple. But I noticed one bad resistor on each board which is the same. R11, I have no idea what value resistor goes into R11? I do have the parts listed on this spec sheet but I'm not a 100 percent sure if this for the following amps listed above. This spec sheet says R11 is a 2.26k resistor but at what wattage and if thats the correct resistor for these or this amp?
Thank you!