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UFN

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Everything posted by UFN

  1. Looks like someones been digging in Kevin's archive again ? Carbon Megatron
  2. Maybe check if modelfixings.co.uk have what you need?. Should be cheaper and they have been totally reliable for me in the past.
  3. FWIW I've use them as output transistors on Dynahis and CFAs without problems. Got significantly better N-P matching on them compared to the MJFs as well by the way.
  4. Thanks Congo, I think that did the trick. Not sure how long it would have taken me to work out on my own what the problem was, so really appreciate the help ?
  5. Not 100% sure I see what the problem is (and I am not near the board right now), but that is exactly what I am getting?
  6. Thanks Kevin, I think I have the schematic (at least the one that was linked to the post I quoted). I'll go over the boards in more detail and post again if I can't figure out what's wrong.
  7. Dredging a little in an old thread, sorry. Has anyone successfully built the bal/unbal converter on the eBay-pcbs shown here? I found pair in a box a few weeks ago and put them together, but they are behaving strangely. I have only done basic troubleshooting for now, but I just want to know if the boards are confirmed OK before I start spending more time on them
  8. Not "very hot" I would think. If you have 35VDC input and app. 22V output you are losing 13V*the current draw of the amp per transistor. IIRC the bias is around 350-400mA, so each transistor dissipates around 4-5W at idle. That should warm up the heat sinks a bit, but they shouldn't be to hot to touch. Have you got measurements (of current draw and/or heat sink temp.?)
  9. If you have 35VDC on the output it means the PSU is not regulating, so something is wrong. Check soldering, component positioning and also the values of all components. If everything looks ok, measure the voltage across the voltage reference and zeners (U3/U4 and D1/D2 in the schematic)
  10. Modushop Dissipante 2U/400mm by the looks of it More interested to know if hifi2000 did the customisation to the front and back of if that was someone else?
  11. Fantastic work Søren! Can we see the insides as well please?
  12. I don't think the Stax amps need more than 1 Oz copper because of the low current, but firstly everything here is overkill so if 2 Oz copper is good then 3 Oz is surely better Secondly, the 2 Oz boards will generally take more (re)heating so they stand a better chance of surviving rework which does come in handy for every DIY'er at some point. Last but not least, most of the amp designs have originally been offered to the community through early large GBs and when you are ordering 30/50/100 PCBs the additional cost per board becomes almost negligible.
  13. I think that might have been me here? Fischer SK437 xx STS 2.
  14. One thought of mine was a steady stream of swear words upon realising that the footprints of PCB mount transformers aren't always 100% identical between manufacturers I waited a couple of weeks for boards only to realise that the secondary side footprints were off by 0.2" because I chose a different manufacturer, but the physical size of the transformer was identical. This obviously doesn't apply to e.g. the Talema PCB mount toroids, but it's worth remembering to always check the manufacturers datasheets Other than that I think it is a great idea for transformers under 30VA or so, because PCB mounting is more flexible than bolt mounting IME
  15. In the beginning I soldered most of them. Worked well, but a bit fiddly with smaller connectors (JST XH/PH etc). Then I decided to buy one of these http://www.engineer.jp/en/products/pa09e.html and now I'm not going back to soldering anytime soon
  16. UFN

    Diptrace?

    Have you checked which layer those outlines are in in Eagle on the parts?
  17. FFS Kevin, I just got my "normal" CFA2 boards delivered earlier this week and now you come up with a new version?
  18. I normally solder one of the outer legs on its pad while holding the transistor with tweezers - then it's easier to correct the alignment on the pads if something's wrong. Then I solder the other legs manually and lastly I solder the tab to the pad for good thermal contact. The hot air gun is probably easier, but this works well for me.
  19. I'm not actually sure I'll have any spares - have a couple of local people interested as well. In any case it hardly seems worth it because these boards are small enough that they can be squeezed in under e.g. Itead's 10x10 cm size limit which means you can get 10 boards for $20 excl. shipping. There are several other cheap options as well for boards this size, e.g. Seed Studio etc. So if you are happy with "standard" quality boards and willing to wait a little then it's probably cheaper and easier to order yourself
  20. That was actually what I was thinking as well (got boards on order) . The 20W IRMs are the same size as the 15W modules by the way and they should be fine for SE. For BAL the 30W ones might be needed but they aren't much bigger. //UFN
  21. Maybe ask them, because they are an official LS distributor so they should be able to get the whole range? //UFN
  22. If you're in the EU you should be able to buy from Micross in the UK https://shop.micross.com/products.aspx?i=14 - shipping cost is still a bit steep but not as bad as from Trendsetter. //UFN
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