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6 Klark Tecknik DN27A in for work. Its amazing to me the changes over the years. 2 units have input transformers and output transformers. The two will transformers will get a electrolytic cap change and general inspection. Of the four remaining, the most similar two will get Jensen input and output transformers, cap change and inspection. One unit had permanent power cord modification, that is going to get changed back to the original style power connector.


Link555 Tue, 03/09/2021 - 11:51

Boswell, post: 468141, member: 29034 wrote:
You do like to pile these jobs high, don't you!

It does not look as though the re-capping will take you too long.

No rest for the wicked! These units are fantantistic to work on. Actually all the Klark Teknik stuff is very well build with maintenance in mind.

kmetal Tue, 03/09/2021 - 13:36

I think it should be law that name changes be made or iteration numbers be made, when i manufacturer decides to change the circuitry of a unit. I know caveat emptor is the way of the world, but its kinda crazy to me that you can omit xformers (a sonically significant part) and still call it the same model. Beyond that you could pay more and get less, not so great for the buyer.

Not sure if the DN27a over at Normandy is xformerless or not, i didn't know it was something to look for.

Interesting stuff.

kmetal Tue, 03/09/2021 - 14:54

Link555, post: 468146, member: 31690 wrote:
I think they offered a transformer option from the beginning. They a have designed special daughter circuit board for either transformers or jumpers. From the look of it that daughter board changed over time.

Cool. Always fun learning about our tools.

Link555 Wed, 03/17/2021 - 06:06

Jensen's are in. The quality of their build always impresses me. So nice to work with such a well built part.
I have done the recap now. The DN27A is such a nice design to work on. They made it pretty easy to repair.
The power supply has 20V 0.5A regulators on it...

Attached files

Link555 Fri, 03/19/2021 - 06:26

Thanks, I am trying to keep it away as far as possible from the power supply. The mu metal Jensen can on the input transformer is really effective, but this position is close to the input connection and away from power supply, so it's a win-win situation. So much room inside this box!

I am really awestruck on the layout of this era of KT stuff, so much thought and care went into its construction. Terence Clarke was/is a true craftsman. His chassis design alone is brilliant, certainly one of the best I have seen for maintenance. It amazing to me that this board which essentially a large mulipletaped feedback path of 2 opamps has such low noise. Its a single side PCB without a ground plane!

Link555 Mon, 03/29/2021 - 06:43

Well 6 units are done now. The owner has the Jensens units and has tested them.

2 units got new Jensens input and output xfmrs, two unit had the original Sowter transformer and 2 had no transformers. Word from the owner is add Jensens to the the last 2 units without 4 transformers are now on order.