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Tube amplifier electronics repair

Some pictures: electronics repair. The product name: Dynacord Eminent II. This is beginning to be manufactured in the mid sixties. Initially, all tube design, and later the transistor preamp and tone section. Meanwhile, little change in design as well. This four different input and tone control. A small band certainly met at that time.Well, let’s look at what is inside.

Dynacord Eminent II
Dynacord Eminent II

Let’s look at it:

Tube amplifier review: ventilation grille.
Ventilation grilles

The Horror

Not a reassuring sight of the tape and the cover. This has definitely someone to “improve”. The cover has to be removed:

Dynacord tube amplifier inside.

It’s a horror!

Tube amp and bad capacitor.
The horror.

The “electronics repair”

Okay, this is life threatening! Look at the capacitor. Part of the power supply. there are two pieces of it there. It filters the power not to be so noisy.  In the image shown in green markers:

Electronics repair? No, this particular threat to life.
This is not very good…

The capacitor is made in the original instead (1). See in the picture were located (2). It can be seen that was wrapped around the foam adhesive. Thus it was recorded near the power transformer and electronics. Needless to say, neither the voltage nor the capacity is inadequate. Simply wonderful….

And now reversed. I wonder what horror it wait?

Tube amp verso, two big tube and transformers.
Verso, slightly dirty

Fortunately, so far nothing striking. Just a lot of dust and cobweb. Clearly visible in the power supply transformer and the output transformer. Good large and heavy. In the middle of the two EL34. Now remove the front panel. It’s very simple, just pull it off smoothly buttons on the potentiometer shaft. And some screws out and ready. Thus, completely naked:

Fully open, logical, well-transparent design.
Fully open.

Part of that is the tone control section. A total of four piece of these panels.  The old Eminent II was produced vacuum tube equalizer. It has a new type of transistor circuit.

Tone section PCB
Tone section details

And finally there are the pipes, one ECC81 and two EL84.

Amplifier tubes: ECC81 and two EL34
The little ECC81 and two big tube.

Well, of course, many bugs have been fixed. Thus no terrible and dangerous. 🙂

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