Stock board diagram has eyelet #9 (GND) marked with a ''D''

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Stock board diagram has eyelet #9 (GND) marked with a ''D''

Postby 20to20 » Fri Apr 23, 2010 3:21 pm

Is this a common knowledge thing here? Do I have an outdated bootleg manual? I assume it should be GN''D'' printed there. Not a 435v. TP.
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Postby Bob01605 » Fri May 21, 2010 8:34 am

20to20,

You must have an altered manual or altered pictorial. Below is an ST-70 pictorial that I scanned myself from an original Dynaco ST-70 pictorial. I colored in the transformer wires but the eyelet markings on the driver board are exactly the same. Eyelet # 9 is a ground eyelet for the board and grounds the driver board to the "star ground" next to the quad cap. There is no "G" or "GND" marking on the original driver board or the original pictorial. It is just marked as eyelet "9" on the driver board and on the pictorial.

Bob Latino

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Bob Latino Custom Dynaco amplifiers

http://www.tubes4hifi.com/bob.htm
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Postby 20to20 » Fri May 21, 2010 9:45 am

Hey Bob,

It's on the schematic in the Dynaco manual. If someone were troubleshooting they might mistake the diagram marking of the eyelet for a 435v. test point and find nothing until they looked farther. I think the original was to have been marked "GND", if anything.

That's really a great drawing you did, BTW. I'm sure it will endure through history as a superior reference doc, to guide future builders long after the colors of the original leads have faded.
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Postby Ty_Bower » Fri May 21, 2010 11:22 am

Are we talking about the point circled in the schematic below?

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Postby 20to20 » Fri May 21, 2010 12:42 pm

Ty_Bower wrote:Are we talking about the point circled in the schematic below?

Image



No. It's the board diagram
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Postby Ty_Bower » Sat May 22, 2010 9:27 am

Dunno. It seems clear that eyelet should be tied to ground. I couldn't tell you why it has a D printed near it. Page six of the assembly manual says:

65 ( ) Connect one end of a 5" wire to eyelet #9
(S). Connect the other end to solder lug
near filter capacitor.
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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