Known issues:

• Leaky Ni-Cd clock battery

The Ni-Cd battery may be leaking, risking damage to PCB layers & nearby components. Promptly remove the battery & clean corrosion/alkaline salts from the board. Use white vinegar to dissolve salts, but exercise caution as vinegar can corrode exposed metals. A thorough examination & repair may be needed. Replace battery with guide: https://github.com/wiretap-retro/Not-A-Varta

Notes:

To use a non-rechargeable battery (e.g. CR2032), you must remove the topmost diode (see picture) from the circuit.

NOTE: The transistors in the pictures are technically "reversed". The photographer replaced corroded transistors with ones that have a reversed pin layout.

The original transistors are 2N3904 (left, NPN) and 2N3906 (right, PNP) and would have the correct orientation.