Remember the nice Radford STA15 I did a couple of months ago? (You can check it out
here) Well, this is it's matching control unit & pre-amp.
The four ECC83s (12AX7), all check out well within limits, and still nicely matched after years of service. Those main smoothing caps also still performing well, and needed very little in the way of reforming.
Very little wrong with this , except it was full of those Wima caps that tend to short circuit without warning. They'll have to go. There's also a few 50uF 6V electrolytics that are also in poor shape. Noisy switches and pots are taken care of with a little cleaning.
It's owner was saying that the recording output lacked bass. Indeed, mainly due to one cathode bypass being open circuit, and the other reading 7uF of it's original 50uF. Note the brown discolouring round the end cap. Let's get to work....
Replacement caps...
... and finally re-united and playing nicely together once more.
Replacement caps...
Just gorgeous! Is that an "STA 15" next to the control unit?
ReplyDeleteI should have read the top of the page first I suppose... ;-)
ReplyDelete