HIJust take off from Sapporo, Japan but the yaw damper seems refuse to work even in such a beautiful place Please see the pic and if anything that i am not doing correctly? The failure option is off btw.Cheers,Frank

Assuming that IRS is set correctly you have not installed the latest SP and you turned it on while IRS were in ALIGN or ON DC (the first 2 seconds or the first minutes of alignment)With SP1b it was solved. However you can reset by using the flt cont B switch, put it to off, then on, and recycle the YD switch.

From pic above you have no electrical feed to the YD. You have Batt Aux & APU selected even though the UPU is off. You have engine bleeds on but need to select 'Gen 1 or Gen 2'. Once you correct this the YD will work.

The aircraft in the picture above is fully powered.PS: The selectors you are talking about only select the meters to be shown on the electrical load display. It has nothing to do with what is feeded or not.When the aircraft is fully powered all the positions will show at least a voltage (except for apu if it's stopped or the engines if they are stopped)

No, it's not. Look at you AC panel, you have APU secleted. This needs to be set at Gen 1 (Engine 1 or Engine 2 Gen 2) to supply power during flight. APU is switched off in your pic.

There is no need to set the meter to one or the other source, except for monitoring, that switch is to "tune" ammeter and voltmeters on te selected source.The AC sources will be selected by the 5 switches APU GEN (2 switches) GEN 1, GEN2, GND PWR.In the picture the aircraft is in flight condition, pressurized, fully powered, and with YD inoperative.A failure in YD power source will trip the switch to the off position, in the picture is still on.If no sources are powering the plane a lot of amber light (BUS OFF in primis) should be on...Please, read the manual.And... if no AC power is avaiable on the aircraft, why the windows heat are working?

Just turn gen 1 on & reselect YD off & ON & it will stay arm & stay on.

Again... GEN 1 is already ON, same for GEN 2.If you don't trust me, load FSX and play with the switches...

I do trust you but you picture shows Engine bleeds on which is correct but your power panel is on APU which is off. I used to fly the 200 series of this type & ac gen should be on gen meaning generators (engines) so that the aircraft systems like YD are powered by more than just the battery.

On the 200 it works at the same way, the knobs are only used to tune voltmeters and ammeters, THERE IS NO RELATION TO THE METERS and what source is powered, the knobs are here only to sow pilots what is in use.This is from series 100- to the 900.The confirmation that AUX battery is not in use and it is fully charged is that there is no power consuption, no amperes out, no amperes in.You worked on the -200?And you've not found the difference between meters and power source selectors?

Please don't get personal.

I do trust you but you picture shows Engine bleeds on which is correct but your power panel is on APU which is off. I used to fly the 200 series of this type & ac gen should be on gen meaning generators (engines) so that the aircraft systems like YD are powered by more than just the battery.

As Andrea says, those switches only select what the electrical meters read. They have no effect on power distribution. That applies to all 737 versions, -200 included. Obviously it makes sense to have the meters selected to read the connected power source, but it isn't necessary.Kevin Hall

I do trust you but you picture shows Engine bleeds on which is correct but your power panel is on APU which is off. I used to fly the 200 series of this type & ac gen should be on gen meaning generators (engines) so that the aircraft systems like YD are powered by more than just the battery.

On the NG, The rotary switches you are referring to are only used to select which electrical buses are monitored on the digital display of the power metering panel. They have no effect whatsoever on controlling which electrical systems are actually online.Davierosoft is a professional 737NG maintenance engineer - you can be sure that he knows what he's talking about in regard to aircraft systems on the NG.

Please don't get personal.

No problem here, just understand what I want to explain, those selectors will make no selections about the power sources used in the aircraft, they are here for monitoring purpose and ground testing.The source selectors (AC) are the ones I told you before.Then, if you want to use them as a power selector, use them as you need.

So Andrea,What do you reckon is the problem showing in the pic? Sorry I am very confused. :(

flt cont B switch, put it to off, then on, and recycle the YD switch.

Will that solve the problem? I did load a cold&dark after I landed.