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johnwmclean

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johnwmclean last won the day on August 22 2021

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About johnwmclean

  • Birthday 09/13/1966

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    Sydney
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  1. Happy Birthday Chris! Hope you have a good one!
  2. https://www.headamp.com/products/spirit-torino-valkyria $10,995
  3. Voja, your opening post says you’ve been reading hc threads for 2 years, then how the fuck did you miss spritzers general disposition, man up and grow some, your sensitivity is making me puke,
  4. I dialled back the bias from 20mA to 17.2mA, installed a 562k resistor in parallel over one of the 175k resistors and achieved 24.8V bias voltage across the 20k resistor and Vce of the PZTA42 is 13.25V. Thanks to simmocon on this for the ground work for the 400V Carbon! The offsets on troubled board (after dialling down the bias) drift slowly down from around 5V. Still not sure why at 20mA bias I was getting no drift, I’ll leave that a mystery.
  5. Yes Identical bias for all 4 phases, I have it all out on the bench now and will test and probe to see what I can find. As well as implementing simmocon’s mod for 400V.
  6. And that makes sense. But doesn't explain in my instance why 2 identical channels on the same sized sink have very different thermal drift outcomes. (1 channel has an offset of under 1 volt and stays there and the other channel is around 13V and slowly drifts down to under a 1V in around 40min.
  7. “Normal” behaviour from my experience at a cold start offset is around 10 - 20 VDC and drifts down to under a 1VDC after 20 - 40 minutes. So yeah I thought it’s abnormal.
  8. Great reporting Simmconn, I’ll be very interested in a follow up of where you end up after dialing back. One channel of my latest build has little to no drift at all (no servos installed), which is odd behaviour from my experience. After 45 minutes warmup offset and balance can be trimmed to under 1VDC. From a cold start everything is now under 1 volt and stays that way. I’m curious as to the reason, do I need fix or leave as is?
  9. As long as voltage is good you probably don’t need a load.
  10. Very sad news so sorry for your loss Steve.
  11. I used the C3M0350120D in both the Carbon and GRHV. On the bench I tested the amp boards separately and they worked fine along with the GRHV. In the final build with 2 amp boards connected there was oscillation which caused all sorts of odd voltages, namely 400V over the outputs and a GRHV + rail that read 8V. Funnily enough I could get the amp working with the capacitive load of a dvm killing the oscillation when probing over the GRHV outputs and I had music. I replaced everything back to C2M1000170D and all was stable. To be honest I haven’t done enough testing to know whether the GRHV with the C3M0350120D would be ok in the field or not. But hopefully you can gain some insight from my experience with it.
  12. FWIW the C3M0350120D did not work out in a recent GRHV/Carbon I had all sorts of funky behaviour.
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