Replacing UY42 with UY41

[stephanie]

If you look at the section on the UY42 rectifier valve in this repair story, http://www.vintage-radio.com/recent-...ilips-95u.html
you'll see that Paul decided to remove a socket contact because it's used as a junction point - something that can probably not be a good thing for the replacement UY41.

I figured, instead of possibly damaging the cheap-tat PC board on my Philips even more by removing the socket -- and possibly breaking the socket -- why not just cut the trace leading to one of the UY42's unused pins and bridge it over with a short length of insulated wire?

I did just that, cutting a notch in the track with a Gillette blade and then "jumpering" it. Works fine.

Figure it's easier than trying to desolder 9 pins on a socket, ruining a board even more which would generate to countless hours of muttered swearing and grumbling.

Anyone who wants to restore the radio to its original electric layout can always remove my jumper and bridge the 1 mm notch with a piece of tinned buss wire.

A little victory over Philips' pot-addled designers.
(ok maybe I shouldn't have said that... )

[Aerodyne]

Pot addled, eh... that explains a lot. I never thought of that aspect of Dutch design.
-Tony

[paulsherwin]

The whole UY42 business is very odd. I've never come across one in anything other than a Philips mid 50s set. I think Philips originally intended the UY42 for use in 110V markets, but soon decided that they might as well just remark UY41s as UY42s given the low demand. Even then they didn't sell very many and were left with warehouses full of the things at the end of the Rimlock era, and because they knew that these UY42s were actually UY41s they decided to use them up in 220-240V sets even though the paper specs said they'd go bang.

This would have been less of a headache in the replacement market than you might expect, since Philips operated their own service network and their engineers would (I guess) have been told what to do when replacing UY42s.

Paul

[Paul Stenning]

I wonder whether UY42s were UY41s that failed on test but passed the test at the lower voltage.

Rather like manufacturers do now with A-D converters etc, where the lower spec (accuracy, noise etc) one are higher spec ones that didn't make the grade.

[stephanie]

Originally Posted by paulsherwin

The whole UY42 business is very odd. I've never come across one in anything other than a Philips mid 50s set. I think Philips originally intended the UY42 for use in 110V markets,

Makes me wonder too, now that you mention it. This is a 110/220 switchable set - you select either voltage by flipping around a little jumper plug.

This radio was made in Holland, but I bought it from a guy in Lima, Peru (through E-bay) many years back.

Peru, however uses 220 volts. Although I guess the same radio could have been sold in other Western countries that use 110 volts: Colombia, Ecuador, Panama, USA, Mexico, Venezuela, etc.

[stephanie]

Originally Posted by Paul Stenning

I wonder whether UY42s were UY41s that failed on test but passed the test at the lower voltage.

But Paul, how do you account for that difference in internal construction?

If they were just rebadged UY 41s, why would we have to elmiminate that one pin when replacing a 42 with a 41?

[paulsherwin]

Originally Posted by stephanie

But Paul, how do you account for that difference in internal construction?

If they were just rebadged UY 41s, why would we have to elmiminate that one pin when replacing a 42 with a 41?

I'm not convinced there is any difference. My 1970 Mazda Valve Data book shows internal connections on *all* unused UY41 pins (3,4,5 and 6). They can't all have been used like this. It was quite common for pins marked 'IC' to not be connected to anything, and presumably Philips as the manufacturer would know this. Sometimes manufacturers would indicate 'IC' on a pin to discourage the use of other manufacturer's equivalents.

I don't really know though, it's all just a guess. It's certainly safer to disconnect the relevant pin as you and Paul did.

Paul