akg c28c broken. help!

Archived from groups: rec.audio.pro (More info?)

hi. i just bought a c28c (nuvistor) and it's messed up. the guy i
bought it from offered to fix it, but he's in germany so i don't want
to send it back if i don't have to.
here's what it's doing:
it's quiet and midrangey with the ck28 capsule in.
it's horribly tinny with ck1, ck2, ck3, and blue lollipop caps.
ck28 capsule sounds fine on a 451 body, as do all the other caps.
the n28 power supply says it accepts 110 and 220v at 50 or 60 hz. i
tried 110 and 220 at 60 hz without much diffence.
all the solder joints seem ok. any other ideas what it could be?
thanks,
kurt

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:
> Kurt Ballou <godcity@aol.com> wrote:
>
>>hi. i just bought a c28c (nuvistor) and it's messed up. the guy i
>>bought it from offered to fix it, but he's in germany so i don't want
>>to send it back if i don't have to.
>>here's what it's doing:
>>it's quiet and midrangey with the ck28 capsule in.
>>it's horribly tinny with ck1, ck2, ck3, and blue lollipop caps.
>>ck28 capsule sounds fine on a 451 body, as do all the other caps.
>>the n28 power supply says it accepts 110 and 220v at 50 or 60 hz. i
>>tried 110 and 220 at 60 hz without much diffence.
>>all the solder joints seem ok. any other ideas what it could be?
>
>
> Check the power supply voltages before doing anything. If the supply
> voltages are okay, check the cathode and plate voltages on the nuvistor
> and make sure it's in the right operating region. Check coupling caps.
> Check transformer.
>
> Injecting a 1 KHz square wave through a 1G resistor into the input and
> tracing it down through the circuit can tell you an awful lot too.
> --scott


get your money back. buy another.