Saturday, 21 April 2012

Kenwood TS-450S revival of sound

Sometimes I like to think I can repair radios and similar electronics, probably born from the few successes I have had in the past? In truth I am not a technical radio man but when a part is clearly broke, a fuse has gone or a memory battery is dead I will attempt that kind of fix.

This set has become a creature of total silence, can I change this the way the Yaesu FRG7700 lack of audio was fixed?

Looking inside shows you the way the Kenwood engineers thought out a service program.

My last yacht had a Yaesu GX757 gx 100 watt set. In Venezuela I decided to see if the tuner fault could be solved, the local Icom agents refused to even look at it. From Devils Island,French Guiana, it would tune down but not up, what a bother, I discovered a crack in the board related to the tuner, a short bit of match stick fixed that and it lasted all the way back to Cape Town!

Check how this set has been designed to open out, there is even a slot type hinge which allows you to pull the sets front face out from the main body and fold it open. This is great, as the set is stable and can be inspected. The Yaesu 757gx was not like this at all!

Carefull inspection with a magnifying glass, soon showed me a break where this Siemans capacitor was installed. Its not a genuine part? its number is Siemens 470up (T) 40v 85209 85c  the case is further marked V6.

The capacitor prooved to require re soldering on both terminals, note, use a low power soldering iron, the one I used was just 16 watt, probably still on the high side. The soon to be repaired, Philips SBC 320 rechargeable soldering irons 5 watts is probably a better choice?

Sound? no not yet but with the Siemens capacitor repair, the speaker is now live and there is a low scratching sound from the speaker but no broadcast or marine band reception. At least I now know that the squelch and audio knobs do at least still work, I used a dash of very light spray oil on them and I am not sure this is a good idea but it worked on the FRG7700!

How hard can this be.