Hi, first of all, I have made progress this week on the LPS for the 103. I also learned, for those interested in this subject, that the 105 and 103 do used the same SMPS, but in the case of the 105, the SMPS does not supply +/-15V. As such, our LPS design for the 103 will be the same for the 105. We can simply omit the transformer and +/-15V supplies, focusing only on the 15V and 5V digital high-current supplies.
Instead of a single transformer, I have chosen to use three separate transformers for +5D, +15D and +/-15A supplies. I initially underestimated the current demands of both 5V and 15V digital supplies, but now have that worked out. I need to order two more transformers and work out the final high-current regulation circuit for the 5V supply and design the final PCB. Space and heat rejection are the biggest hurdles here. I know that it will fit, but I have to evaluate the heat rejection and how this is best accomplished to avoid over-heating the player. I already have this worked out conceptually, but still need to implement everything and test.
I am quite confident that this will make a NOTICEABLE difference in ALL aspects of the units' performance. SMPS's are notoriously noisy due to RF switching frequency. This noise will be present not only on the power trace, but also radiated inside the player. A LPS (Linear Power Supply) is transformer based and does not use any switching. It a much more expensive way to provide power, but is a better solution for audio. If Oppo built full LPS supplies for these players, their price would be QUITE a bit higher! It makes sense for DVD mfrs. to use SMPS's because of their cost, space savings and efficiency.
I plan to offer mods for the 103 in two forms:
1) LPS upgrade.
2) Analog stage upgrades, in the form of component upgrades and minor redesign, to improve sound.
The goal for the 103 upgrade is, of course, a high-value mod that will serve the needs of those who are using it ONLY for video and as audio transport. The other mod will be for those who use it for audio and music as a player.
Thank you, more to come!
Dan W.