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Old 2nd Mar 2019, 7:39 pm   #94
chriswood1900
Octode
 
Join Date: Jan 2007
Location: Bristol, UK.
Posts: 1,081
Default Re: Hedghog standards converter

Another Hedgehog is born, arrived in bits over the last 6 weeks and came together on the 25th Feb. It was my first experience of building a project using mainly surface mount technology. Iím fortunate in still having steady hands and good eyesight albeit very short sighted, which seems to help.
I was nervous of so many small components so I set up my work area with very bright LED lighting on a raised platform on my bench. I first fitted all the large switches sockets and non surface mount components using 1.5mm lead free solder and a chisel tip soldering iron.. This was then followed by the SMD resistors, capacitors transistors in numerical order and then the ICs doing the TVP5150 last, I used 0.7mm lead free solder and a very fine bit in my Metcal iron holding them in place with very fine angled tweezers. Most parts went on quite well and my speed improved as I got used to holding parts in place and soldering one side then the other with only a couple tombstoning. The hardest part I found was getting IC1 the TVP5150 IC in the correct position on all sides, I first tacked pin 25 and then discovered it was slightly out and then damaged the pin and pad trying to move it, fortunately pin 25 doesnít do anything so I managed to re-position it using a microscope and get it working with out the pin!!
It took me approx. 6hrs in total but I did take frequent breaks to rest my eyes and spent some time double checking my layout and the component values with tweezer probes, I only removed parts from the packaging as I was ready to fit them as the Caps have no markings and are easily mixed up.
Finally I connected it to a bench supply at 7.5V set to 250mA and powered it up, the LED was a bit dim but when I tuned my Sony 9-90UB I was rewarded with a grey scale and then a testcard, all the switches worked as expected and after a few firm taps to check for bad joints I was happy it was all working first time.
A big thanks to Frank for developing this project and to Jeffery for providing guidance, just shows what can be achieved by the community.
I attach a couple of photos not great quality and the bar on the picture is an artefact of the Cameras shutter speed.
Chris
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