Anyone have a few pointers on where I can acquire the Canadian version roadmaps? There are additional circuits on my board creating havoc that are just not on the KU maps. STK's are removed, 150ohm resistors in place. The right channel 1,2,3 module traces are full rail -39V, if the 1-3 emitter resistor is removed it comes out of protection. The collectors on Q16 is 39v, Q14,Q12, are at -39. North of Q16 on the board is a Zener diode, a 4.7 50v electrolytic cap, and 330ohm resistor. I flipped the PNP transistor Q16 and the collector went to 1.4v like it is supposed to be. Q14 and Q12 are drop to -34v on the collectors. If I put the emitter resistor back the 330ohm resistor becomes a smoke show.
SX-780 KC Board connection and schematic diagrams, HELP!
- Thread starter KePip
- Start date
Register to hide this ad
Hi new member,
I do not think pioneer published anything specific to the KC model for the sx-780. Sometimes the schematic might show the variations.
I have seen numerous times where the KC (Canadian models) models must meet CSA regulatory requirements/approvals, but that is usually on the primary or line side of the transformer.
For instance in the SX-1250, the original soft-start PCB awr-107 on the KU (USA) model, would not qualify for CSA, so pioneer was forced to come up with another design, addressing the issues (soft-start resistor and the contact with the thermal fuse). Thus they designed a awr-115, which was never documented. I have a pic of one. Consequently follow on models, sx-1980(awr-154), 1280(awr-157) used the methods used for the awr-115.
So I am not sure if the amp in the sx-780 KU is any different than the KC. If there is it's undocumented. It's quiet possible that both later production models have these undocumented changes. But that does not mean that it can't be troubleshoot. The amp is fairly simple, you have a differential input stage, followed by a voltage amplifier stage having a constant current source as the load. In between the VAS and CCS you have a bias spreader (internal to the stk) which produces the voltage to bias the output stage. The two 150-ohm resistors, substitute for the bias spreader. The CCS current is in the 10mA range.
I have to look at the schematic to figure out the parts you are referring too. You could take the existing KU schematic and modify it to make the KC version, noting any differences. You could also post a pic so we can compare the layouts between KU & KC models
Good luck
I do not think pioneer published anything specific to the KC model for the sx-780. Sometimes the schematic might show the variations.
I have seen numerous times where the KC (Canadian models) models must meet CSA regulatory requirements/approvals, but that is usually on the primary or line side of the transformer.
For instance in the SX-1250, the original soft-start PCB awr-107 on the KU (USA) model, would not qualify for CSA, so pioneer was forced to come up with another design, addressing the issues (soft-start resistor and the contact with the thermal fuse). Thus they designed a awr-115, which was never documented. I have a pic of one. Consequently follow on models, sx-1980(awr-154), 1280(awr-157) used the methods used for the awr-115.
So I am not sure if the amp in the sx-780 KU is any different than the KC. If there is it's undocumented. It's quiet possible that both later production models have these undocumented changes. But that does not mean that it can't be troubleshoot. The amp is fairly simple, you have a differential input stage, followed by a voltage amplifier stage having a constant current source as the load. In between the VAS and CCS you have a bias spreader (internal to the stk) which produces the voltage to bias the output stage. The two 150-ohm resistors, substitute for the bias spreader. The CCS current is in the 10mA range.
I have to look at the schematic to figure out the parts you are referring too. You could take the existing KU schematic and modify it to make the KC version, noting any differences. You could also post a pic so we can compare the layouts between KU & KC models
Good luck
Last edited:
I have an 3½Mb file I can send that is for the KC/KU units. The site will not accept or host links and will not permit upload of files that large. I have that file saved in my web space.
It's not substantially different from the other versions, except that everything is 1.26 times more - Not including any tariffs.
It's not substantially different from the other versions, except that everything is 1.26 times more - Not including any tariffs.