Catwalker

Freedom Is Not Free To my American friends on memorial day, thanks. And to those who never made it back, thanks just does not cut it.

On the left is the audio amp board, on the right are the two audio amp IC's (did I mention I H*A*T*E desoldering and resoldering Integrated Circuits? Thankfully these have only ten pins :-) ) The chip on the extreme right is the good one the one to its left is the dead one.
Two electrolytics, the one on the left with the disc ceramic cap and resistor is one being replaced (there are two assemblies like this to be replaced) Notice how much shorter the new one is?
 The new one now with a disc ceramic cap and a resistor added.
The rig purring away nicely. Still some stuff to do, but it is now functional and at least I can listen in. The pile of parts in front are the bits I have replaced so far. 

 

 

 

 

 

 

 

 

 

 

じゃね

It has been a while since I started and completed an electronic project, but that is what I decided to do this weekend. I built myself a piece of test equipment:


This is some of the raw materials I picked up today from Queale Electronics in Victoria, in addition to a few bits from Digi Key electronics. (Man, solder is expensive these days...)




Normally, when I build an electronics project, I take the time to whip up a printed circuit board, but this time, in a desire for simplicity, I went for a prototyping board. The schematic for the project is in behind.





Here is the project built but not yet in the case.







Here it is boxed, ready to be closed up. Prototyping makes it look a tad messy, but it works. You can see the speaker on the bottom of the box, stuck in place with a few dabs of epoxy. (Epoxy is S*M*E*L*L*Y stuff)


So just what the heck is this and why did I go to all of this effort to build it?


Well, it is a signal tracer, and I needed it because my venerable old Kenwood TS 820S was sick. It had been sick for some time, but only this week did I get around to working on it, only to discover multiple problems, including dead audio, for which a signal tracer is a must.






Whoops!! A word, if I may?

Never, and I do mean N*E*V*E*R ever short
the ac input of a set of rectifier diodes, to the DC output of said diodes....

At least when the power is on... :-(


The results, as you can see here, are very smelly, noisy and messy, since my dominant hand tends to shake (Essential tremors) I did just that while trouble shooting, thus creating an additional problem.

The eagle eyed amongst you will note that there are circuit traces missing, and a couple of cracked diodes.


Four very dead rectifiers and the replacements just above.





The end result of the repairs needed due to my shaky hand. Four new diodes with protective sleeves (Right side). In addition to two new shiny electrolytic capacitors. (No, they didn't blow, but since the radio is around 35 years old, I decided to replace them, after that period of time, electrolytics become, shall we say, troublesome.


OK, the power supply is repaired, back to trouble shooting, now for that dead audio. Thanks to the new signal tracer, I think I have found the problem, a bad audio amp I.C. off to Ebay to find a 35 year old Integrated circuit. Hopefully I can find some NOS (New Old Stock)


I also discovered that I need a choke for the power supply (unrelated to my shaky hands incident) This is going to be an expensive repair, but well worth it, this old lady (sorry, I am most definitely not PC and never will be) is a grand piece of equipment, and full of memories for me. (I bought this rig from an older HAM - (now an SK) - in 1981 - for the grand sum of $800.00 which was a lot of money for a teenager)

じゃまた。