Saturday, February 18, 2012

Repairs

Today was repair day...

Good news is everything is fixed...or half fixed:

* The FL-110: OK it was not a fix, it was operator problem, the FL-110 RF switch doesn't work on badly matched aerials.

* The FT-7: Works but was not completely fixed, I have to get to a difficult access plug and didn't fell like it today although the FT-7 is of easy maintenance.

After losing half an hour searching for a pdf of the schematic I remembered that it came on paper with the radio...
(Schematic with the possible culprits)

(audio board)

Initialy I thought that it must be some issue with a power line capacitor or one in the audio path, I inspected the audio board and found nothing suspicious, then I thought on the audio output cap, tested with a brand new cap connected to the amplifier output and audio popped up! Cool it's the audio cap, but let me test with an external speaker to make sure it is that the problem (it's always nice to double check). Placed an external speaker and audio was OK, so the problem moved along the output audio line to the external speaker plug, Something to test/clean on the next days.


video
The video, testing to eliminate any possible problem coming from the audio amp. You ear the completely different audio from my test speaker (series with an output cap, "the probe") and the internal speaker when I disconnected the probe.

* A heater from a friend: it was easy but not so to spot, there was a hidden thermal fuse inside a cable and that fuse was broken (fused), I did bypassed it for later replacement of a new element. Not elegant but works for this cold days!
(thermal fuse)

The heater

Good, now I have to get some courage to fix my oscilloscope....

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