TI-58 fault - repairable?

[teenix]

Everything looks nice and clean, so corrosion is probably not an issue.

If there is another component that gets warm also, that 'may' indicate the faulty part, or frustratingly, just a symptom of the actual fault which could be bad. I would not turn it on again without some sort of servicing.

As you mention all voltages are lower, it may be that the power supply module has failed and is not oscillating properly. This can cause high battery currents through the coil and heat it up. The components around the coil usually fail before the coil, so possibly the transistors or as Jeff pointed out, the capacitors. There are also a couple of diodes there, possibly zener type, which could have failed also.

From the image, the power module looks like a sandwich assembly so I don't know how hard it will be to try to service it. The capacitors and maybe diodes will be marked and easy to get. The transistors may not be so easy if they have part numbering similar to HP.

A bit off topic, but I always wondered why, on circuit boards of this era, the protective coating always has a bubbled effect on the traces.

Edit: I don't know much about TI models, but it appears the power module was outsourced by TI and is why there are no circuits for it. Unless there are traceable numbers for the parts, it might be hard to repair (if it is the faulty part).

cheers

Tony