Curious Question about the older E3s

[JR 500系]

 

 

As the topic suggests, I am puzzled for quite sometime now after I've seen the E3 coupled with the E5 as a Nasuno or a Yamabiko service... I am curious as to why the E3 would still be coupled with the E5 for this, seeing that the E3 no longer serves the Komachi service from Sendai to Akita? 

 

The video above shows the E3 running with the E5 as a Yamabiko, splitting off at Sendai and proceeding all the way to Akita, as a 'not in service' train... Only to also return back to Sendai also as a 'Not in service' train, which I reckon to be combined again with an E5 for the trip back to Tokyo? Wouldn't having an extra 'Not in service' train means more signalling work? This puzzles my curiosity much haha ~

 

[bikkuri bahn]

It’s for the monthly maintenance inspection, which occurs at the Akita rolling stock depot.  These movements occur about two or three times a month.  

[Densha]

After being replaced by the E6 series on Komachi services, the Akita Shinkansen E3-0 series became redundant. But not all of them got scrapped. Two sets were reformed for usage on the Yamagata Shinkansen as 7-car E3-1000 series L54 and L55 formations, whilst two other sets were rebuilt into the Toreiyu and Genbi Shinkansen. Two more sets were kept in their original Komachi condition, and have since their retirement from Komachi services in 2014 been used to increase seating capacity on busy Nasuno and Yamabiko services. This explains why you will still see original E3-0 series coupled to E2 or E5 series on the Tohoku Shinkansen. Wikipedia has the complete story.

[Sacto1985]

On 8/25/2018 at 8:06 AM, bikkuri bahn said:

It’s for the monthly maintenance inspection, which occurs at the Akita rolling stock depot.  These movements occur about two or three times a month.  

 

Since the E3's are now limited to mostly Tsubasa service up to Shinjo on the Yamagata Shinkansen line, I wonder why they didn't just move the E3 maintenance facilities to the Shinkansen yard northeast of Sendai instead.