kat 6550

[davebms]

Hello all ,I do not use this amp as often as i should (i live with a tv watcher)
but have a small system upstairs But a while ago switched on buzz sound
and magic smoke, thought prob the evox rifa across the switch had gone pop
to day my boy came, so i got him to lift it onto a coffee table, sowters very heavy ,,The input/ noise suppression cap is ok, but will replace with a plastic
one any way, The problem is the dc heater supply caps are short circuit IN5821 blown up ,heater wiring has got hot. so re cap required,, all under control
But the black gates they test sort ok, but probably best put in the bin !!!
what do peeps use these days ?

dave

[John Caswell]

Hi Dave
Personally I have never bothered with boutique components, I just use good ordinary commercial components from RS, Farnell, CPC, Cricklewood and the like.
When you get around to rebuilding it would be a good idea to add a fuse in the heater wiring from the transformer.
I will have a look tomorrow at the schematic and give you an idea of the fuse value. It will need to be an anti surge/"T" type to handle the surge of the capacitors charging and the cold heater current.

John

[Greg.]

Originally Posted by davebms

But the black gates they test sort ok, but probably best put in the bin !!!
what do peeps use these days ?

A good question. I Googled ‘What to replace Blackgate capacitors with?’ and found a wealth of information. Fill your boots or follow John’s lead. It’s your choice!

[davebms]

hello all,, well its working (has been for 3/4 weeks)changed the LT caps fitted
new diodes. re wired heater supply, fitted slow blow 8amp fuse in holder rear
off amp. 4 kt20 plus small valves ,520 ohm bias resistor,s with ammeter in heater supply, pulls 9.4 amp drops to 7.4 ish (sorry no calculations involved
i changed c1/c2 the other power caps are big evox rifa they check out fine
all black gates in bin ! nichicon fine gold /nichicon muse fitted this is the best its
ever sounded the kt20s give a LOT off sound low mid volume it must be pretty
good as i was playing some random stuff from my phone my boy said THAT IS **** but it does sound good the ,,ally heat-sink keeps the trany cool all looking good

Dave

http://www.world-designs.co.uk/forum...1&d=1653153150

[Paul Stoneman]

Good evening forum members, not really a reply but on the thread, does anyone have a copy of the KAT6550 or KIT 6550 I guess, build schedule they could E mail, sell or what ever. I have a repair on an amp that has had some alterations.
Thank you.

[Greg.]

PM me your email address and I’ll forward to you.