NAD: Same as the first (but a whole lot worse?)

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7704A

7704A

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Another non-functional one came up cheap enough so I pounced on it. The last one turned on but had no sound due to a shorted cap and blown HT fuse. This one doesn't even power on, and the mains fuse doesn't look blown. Will have to clear off the operating table and have a look.

Edit: I will say though, this amp seems to have escaped the diamond-plate maniac who got to the last one. Self-cutting sheet metal screws into plywood? Really?
 
These are super underrated TBH, i've had them as backline quite a few times, and they are quite big sounding
 
DanTravis62 said:
These are super underrated TBH, i've had them as backline quite a few times, and they are quite big sounding
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Along those lines, one of my prouder moments with the other VK100 was taking it to the house of a friend who is a self-proclaimed lover of loud, and him saying that we need to turn it down. The air in the room felt like it was pressurized by the amp.
 
One thing my local tech always said, don't buy an amp if it doesn't power on (and the fuse is good).
Good luck!
 
Racerxrated said:
One thing my local tech always said, don't buy an amp if it doesn't power on (and the fuse is good).
Good luck!
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That's good advice. I didn't follow it here, because I'm ok with projects if they're cheap enough and based on the common issues with these amps, the fix is likely cheap and easy (read: not a transformer replacement).
 
Popped the hood, looks like it's the underrated heater diodes I've read about. That, and a near-dead fuse.
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That cracked diode actually peeled open with a little convincing, it was that bad:

20240526_141551.jpg


Toasty fuse:
20240526_141456.jpg


The board looks like it is a different revision than the other VK100 I grabbed. Maybe an earlier one? Some connectors are different, I don't see a bunch of the yellow hot-snot stuff holding them down, some wires pairs are twisted that I don't think were on the other amp, depth and presence controls have one three-conductor shielded cable going to them instead of two two-conductor cables, and I have a sneaking suspicion that the power transformer is significantly bigger on this model then the other one. We'll see how it sounds once it's fixed up. I have the means now to install eyelets in the board, so I might do that for the fuse to make it easier to change out in the future instead of pulling the whole board out.
 
If it’s cheap, has 4 tubes and a loop I can work with it.
 
I really miss my old VK head. If I could get one again cheap, I probably would!!!
 
Cant stand board mounted fuses...bogner must have been influenced by peavey
 
Smashedguitaris⸸ said:
Cant stand board mounted fuses...bogner must have been influenced by peavey
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I wouldn't mind if I didn't have to pull the board to replace them. A good thru hole plated pad so that I can desolder from the top, or an eyelet, or having the traces on the same side as the components, or... Yeah. Basically I think it's the board that's the issue here.
 
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