MX-1000 Sub Circuit Board Changes

I emailed Yamaha Support but didn't get a reply beyond acknowledgement my question was received. There must have been a service bulletin sent out though because there are older versions of the boards with the modifications.
 
So, do I further apply the updates (comments/ observation from #7-9) to my boards which already have the soldered together 12 mH, 330 ohm, 1uf capacitors to the one 2.7k resistor?
 
raycarr00 said:
So, do I further apply the updates (comments/ observation from #7-9) to my boards which already have the soldered together 12 mH, 330 ohm, 1uf capacitors to the one 2.7k resistor?
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Does the serial number of your unit start with E01..?
 
That is a factory modification to the first production boards. The later boards had incorporated tha same changes neatly on the boards. On the schematic I believe the components are reflected in the schematic. Should not need to modify either configuration unless the components are bad.
 
avionic said:
That is a factory modification to the first production boards. The later boards had incorporated tha same changes neatly on the boards. On the schematic I believe the components are reflected in the schematic. Should not need to modify either configuration unless the components are bad.
Click to expand...
I am curious of the serial number. Have been tracking these.
 
E02. Ends with SU. 1689 sandwiched in between. Yum! :rant:
Okay. Will replace all components on the updated mod. for reliability.
Current values: inductor 12.7 mH, 2711 ohm resistor, 331.4 resistor, 960 nF cap/ Esr 2.9.
Using metal film of same wattage on resistors and poly metal film for cap.
All caps, resistors, trannies, testing good on L ch. so far. Will keep most.
2 Diodes 5kf10b values don't jive- Ir 78 na, uf 483 mv, c=156pf/ Ir 87, uf 476, c=145pf. I'll look up data sheet.

Still working on the board. Writing down values on L ch to compare with R ch.
Issue: Protection light, no output. No apparently burnt -leaking components. No signs of missing traces. So far. Lol!
Love those radio hack desoldering irons!
Recommendations appreciated.:thumbsup:
 
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raycarr00 said:
E02. Ends with SU. 1689 sandwiched in between
Click to expand...

very interesting, thank you!

I have seen and worked on quite a few MX-1000's

Only one with E01...serial number. The revision components were missing all together
Two with E02...serial number. The revision components were on the boards already. I noted minor variation on the boards comparing to later E03..+ units.
The rest were all E03...and up.

This being said, I am assuming that the factory modes such as the modes done to your unit and Sonavor's unit, were done to early E02...units, with later E02...units having the boards updated.
 
I tested from cathode center pin to anode right pin on both 5KF10B diodes and the results are consistent, now. .397 or .392 with a dmm.
got to watch out with those Chinese(german) testers!
 
sonavor said:
Here is a picture of the component side of the two versions of the left channel sub circuit board. The top picture shows the original board with the modification that added the four additional components. The bottom picture shows the updated version of the board with the four components in designated locations.

I'm currently updating the left channel sub circuit board modification on my board with new components. The schematic here is not in the same order as the original setup or pictures. The original setup and pictures here goes like this: one side of 2.7k resistor to 12mH inductor to 330 ohm resistor to negative side of the 1uf capacitor positive side of 1uf capacitor to other side of 2.7k resistor. The schematic displayed here goes like this: negative side of 1uf capacitor to 2.7k resistor, positive side of 1uf capacitor to 12mH inductor to 330 ohm resistor to other side of 2.7k ohm resistor. Which one is it?


MX-1000_LCH_sub_ckt_pcb_diff_02.jpg
Click to expand...
 
Does anyone have any pictures of this thread?

I have MX-1000 and left channel has mysterious oscillation...
I would be interested in what the updated connection does. Mainly what is the purpose of the L301 inductor
 
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