Phenolic PCB tracks & transistors. - UK Vintage Radio Repair and Restoration Discussion Forum

Argus25 · 16th Sep 2017, 12:17 am

I thought I would add this information/technique to the forum. It was developed to preserve the tracks on vintage phenolic pcb's where transistors mount. It also results in some germanium transistors with long leads being able to be fitted with zero soldering/heating. I did this for my Eddystone EC10 radios and it made it easy to try multiple transistor types.

A jig is made with a piece of old electrical bus bar and pcb pins and a screw down brass wire clamp is added. This makes a tool for forming the transistor leads to the exact spacing as the hole array in the pcb. Brass hex head screws are used with the head side on the track side and a a nut is used on the component side and the heads soldered over. Another nut & washer is used to secure the transistor. Its also easy to make a mini socket wrench from an Allen head screw soldered to a screwdriver end with a brass tube section.

The attached photos tell the story:

Nickthedentist · 16th Sep 2017, 10:20 am

What a wonderful idea, well executed. Thanks for sharing.

G6Tanuki · 16th Sep 2017, 4:03 pm

Nice one: Most cunning, functional, and neat-looking too!

GW4FRX · 16th Sep 2017, 4:38 pm

Inspirational -- thank you very much for posting this.

16th Sep 2017, 4:56 pm

The sockets from turned pin DIL headers also do the job

MrBungle · 16th Sep 2017, 5:39 pm

Looks neat but I'd be worried about nuts falling off and shorting things out.

Argus25 · 16th Sep 2017, 9:54 pm

Quote:

Originally Posted by MrBungle

Looks neat but I'd be worried about nuts falling off and shorting things out.

I guess that could be possible if the entire unit was subjected to extreme vibrations, but when I go back to this system to remove the nuts or change the transistors, the nuts always appear to have the same tension I tightened them to in the first place. So they are probably no more likely to fall off than any other nut. I guess if there was a concern for something exposed to extreme vibration, mini lock washers could be used. At least with this system, vs some form of socket pin, the transistor itself can't fall out.

Also, and I'm not 100% sure if this is true, or not, it seems that very small sized screws and nuts, with a very low mass seem to uncommonly come loose. For example in watches & clocks with many of these they appear to stay put most of the time without thread lock or lock washers. It would be interesting if anyone has a theory on why this might be or even if this observation has any merit
, perhaps something to do with F=Ma?

ms660 · 16th Sep 2017, 10:14 pm

Weight/thread slope ?

Lawrence.

julie_m · 16th Sep 2017, 11:23 pm

Thin parts deform more easily and provide a similar effect to spring washers?

16th Sep 2017, 12:17 am	#1
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Phenolic PCB tracks & transistors. I thought I would add this information/technique to the forum. It was developed to preserve the tracks on vintage phenolic pcb's where transistors mount. It also results in some germanium transistors with long leads being able to be fitted with zero soldering/heating. I did this for my Eddystone EC10 radios and it made it easy to try multiple transistor types. A jig is made with a piece of old electrical bus bar and pcb pins and a screw down brass wire clamp is added. This makes a tool for forming the transistor leads to the exact spacing as the hole array in the pcb. Brass hex head screws are used with the head side on the track side and a a nut is used on the component side and the heads soldered over. Another nut & washer is used to secure the transistor. Its also easy to make a mini socket wrench from an Allen head screw soldered to a screwdriver end with a brass tube section. The attached photos tell the story: Attached Thumbnails

16th Sep 2017, 10:20 am	#2
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,843	Re: Phenolic PCB tracks & transistors. What a wonderful idea, well executed. Thanks for sharing.

16th Sep 2017, 4:03 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: Phenolic PCB tracks & transistors. Nice one: Most cunning, functional, and neat-looking too!

16th Sep 2017, 4:38 pm	#4
GW4FRX Pentode Join Date: Aug 2005 Location: Shrewsbury, Shropshire, UK. Posts: 149	Re: Phenolic PCB tracks & transistors. Inspirational -- thank you very much for posting this.

16th Sep 2017, 4:56 pm	#5
Guest Guest Posts: n/a	Re: Phenolic PCB tracks & transistors. The sockets from turned pin DIL headers also do the job

16th Sep 2017, 5:39 pm	#6
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Phenolic PCB tracks & transistors. Looks neat but I'd be worried about nuts falling off and shorting things out.

16th Sep 2017, 10:14 pm	#8
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Phenolic PCB tracks & transistors. Weight/thread slope ? Lawrence.

16th Sep 2017, 11:23 pm	#9
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Phenolic PCB tracks & transistors. Thin parts deform more easily and provide a similar effect to spring washers? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.