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Bush VHF81

I was very fortunate to get my hands on this Radio for a mere ten pounds.  They are fairly common, and not particularly desirable to collectors - but I was quite pleased to get hold of one because it is the last production valve radio made by Bush in the 1960s.

The radio itself was in fairly good condition, but the case has seen better days.  At some point it had got wet and one of the corners had come unglued.  I reglued it using PVA adhesive, but refrained from making any other changes to the case.  It will be a radio for my workshop, so looks aren't all that important.

Turning the radio around, and opening it up, revealed an amazing amount of dust!  This isn't unusual in valve equipment because the heat tends to cause air currents which in turn move the dust around.

Hoovering out the dust made it a lot easier to see things, and the chassis was removed from the case.

Next, I turned my attention to replacing the capacitors.  There was quite a few paper-in-oil capacitors which dry out over time.  In fact, some of the capacitors had already been replaced at some point in the past.  Such as this one.

However, despite being newer than many of the capacitors inside the radio, this was far from perfect!  As can be seen by the measured capacitance.

This shows the importance of replacing older capacitors.  There is another reason why they should be replaced, but more on that one later!

Each of the suspect capacitors was replaced with a modern equivalent - which should see many the radio last for many more years of service.

Having replaced all of the suspect capacitors, I tested the radio electrically, and then switched on.  It worked!  I didn't even need to replace the mixer valve - as this seems to have been replaced at some point in the past and is still good.

I soak tested the radio in the workshop for a few days and all appeared to be working correctly.  However, suddenly it stopped.  No warning, it just stopped.  A small amount of investigation revealed that the fuse in the plug had gone.  Now, here is a golden rule - Don't assume that the fuse has just got tired and replace it.  Check for any potential faults as well.

I dug out a new fuse from my ancient supply - 49p from Woolies at some point in the dim and distant past - and replaced the fuse.  I then switched on and was greeted by an absolutely almighty bang, followed by a smell of burning and a cloud of smoke.  I also blew the breaker in the workshop!

The culprit was the one paper-in-oil capacitor which I had somehow managed to forget to replace.

They tend to do this!  Once the oil dries out, they explode when voltage is applied - disgorging their innards.

Once this capacitor was replaced, the radio worked once again - and has continued to do so ever since.  It just goes to prove - check your work, and check again.