A transistor doesn't just crack without a reason.
Have you checked the zenerdiode at the collector?

Martin

Hi Martin-

I replaced both zener diodes in the neighborhood (137 and 138).  I didn't test the old ones, just replaced them.  Hoping that a PNP BC212B is an appropriate replacement for TR10.

Jeff

Tried a BC212B for TR10 and that did the trick.  I have FM working again.  i understand that i need to put some heat paste goo on the zener diode to keep it in tune so i'll go get some CPU heat sink paste. Looks like the "on" light bulb and the tuning light bulbs are burned out and it has the original orange capacitors so probably time to replace a bunch of parts to get it working like new again.

Don't use the fancy modern grey heat sink paste - it dries and hardens in weeks.
Use the good old white stuff.

A servicekit is available, containing new radial and axial capacitors, tantals, trimmers and lamps.

Martin

Thanks Martin,  I bought your service kit (and a couple of the tuning dial covers), and it arrived a couple of day ago..  I didn't think you ever needed to replace the tantalums so i was surprised they were in the kit.

Best, Jeff

Yes tantalums are different so I would not replace with aluminum electrolytic but would be interested if anyone else has opinions on the matter, Also they do not seem to drift in my experience, I would think to replace them with aluminum electrolytic would just be causing a problem for the future with no benefit?

Discussions about tantals are still going on and I get emails about the subject almost weekly, so please let me
copy and paste a previous post of mine:

Tantalum capacitors (tantals) were - and stil are - relatively expensive components, but they were
chosen for a reason, - not because a capacitor was needed and some tantals just happened to be in the drawer.
Tantals have certain pros over aluminium capacitors, that really shouldn't be ignored;

Tantals have much less leakage.
Tantals have a much better temperature stability (10-20 times that of an aluminium electrolytic cap).
Tantals have a much lower ESR (10 times or more). The lower ESR also means that they have
a better volumetric efficiency, i.e you can, popularly speaking, "fit a 1uF tantal where you would otherwise
have put a 10uF aluminium cap". (Of course it's not like that in all cases in reality and calculations will decide
the capacity needed, - but it helps to give an idea of the quality levels of the components).

Tantals are much less noisy. They don't give the same "burst" of noise when charging and discharging begins, that aluminium caps do.

In short, tantals are more "perfect" capacitors than aluminium caps. This makes them the superb choice for some circuits.
 - And less attractive for other.

Generally speaking, tantals are the best choice for audio and video circuits, filtering, preamplifiers,
tonecontrols etc. = the finer workings.

Similarly aluminium caps should be chosen for power supplies and the likes = the rough and tough workings.

It should be said though, that due to their very low ESR, tantals shouldn't be used in circuits with
a healthy amount of feedback (unless taken into consideration of course).
Keep them away from audio output stages etc. Use standard aluminium caps here (non-low-ESR is fine).

If you fit f.e. a 10uF 63V aluminium capacitor in a circuit where it will only ever see a few volts - like
coupling capacitors in a typical preamplifier circuit, it will not be excited and it will die
faster than if it was used up closer to its rating, even if only occasionally.
You could say that aluminium caps can "die from boredom".
Tantals generally don't show the same tendency, they will last longer even if not excited and
they typically have a lower voltage rating too, so it's not at all as much of a problem.

Early Beocord 6-8000s (a.o.) is a great example, where aluminium capacitors with a too high voltage rating were
used in the signal paths in some production units. Lower voltage rating aluminium capacitors were then fitted
instead but tantals would've been the better choice here, really.

But nothing will last forever and tantals are no exception, they will eventually go bad and I
wouldn't expect any and all of the ones fitted up through the 1960s and 1970s to still be
working today, though surprisingly many will be found showing no signs of aging.
In 1960s and 1970s B&O units, a typical pattern seems to be that the tantals are either still all good or all marginal.
In other words, if one tantal is found bad - you might as well replace the lot.

When repairing and restoring, it's a good general handrule to use tantals where the designers used tantals.
They were chosen and paid for for a reason.

Martin