I have a pile of K4900 chassis I am starting to test/work on and have been compiling the below info (Thanks Ken Layton and Modesitt and ecwestjr) from numerous posts.
Info:
3 versions:
"Latest" version had Vertical Dampening pot and a Vertical Position circuit board attached to the main board. (-040 confirmed below)
-040 , -055, -057
Yoke: 2021111258 or 2021111264
"Intermediate" version had a Vertical Dampening pot and NO vertical position circuit board.
-034 , -037
Yoke: 2021111258 or 2021111264
"Early" version did not have either a vertical dampening pot or a vertical position board. (Confirmed Below)
-023
Yoke: 2021111194 or 2021111201
"The early version is not compatible with either the Intermediate or latest versions due to the yoke being slightly different. If you use an early chassis on either one of the later ones, you'll get a foldover you can't adjust out as stated in the bulletin."
Service Bulletin:
"This bulletins applies to 4900 series monitors with serial numbers of 400001 and above. They can be identified by the following:
A) The model number on the monitor is printed in red.
B) The part number on the deflection yoke is either 2021111194 or 2021111201.
C) The flyback transformer stabilizing bracket is labeled 611X0005-008 (note: from my own experience this label always falls off so look all around inside the game cabinet and underneath the monitor main board for it).
D) There is an additional control, the VERTICAL DAMPING CONTROL immediately to the right of the vertical hold control.
NOTE: K4915 uses different Yoke than the above
Yokes with part numbers 2021111194 or 2021111201 are for use with early production run 4900 series and should not be used with this version chassis as insufficient vertical deflection, vertical foldover, or improper blanking will result."
https://forums.arcade-museum.com/showthread.php?t=38883
https://forums.arcade-museum.com/showthread.php?t=326143
https://forums.arcade-museum.com/showthread.php?t=142056
Info:
3 versions:
"Latest" version had Vertical Dampening pot and a Vertical Position circuit board attached to the main board. (-040 confirmed below)
-040 , -055, -057
Yoke: 2021111258 or 2021111264
"Intermediate" version had a Vertical Dampening pot and NO vertical position circuit board.
-034 , -037
Yoke: 2021111258 or 2021111264
"Early" version did not have either a vertical dampening pot or a vertical position board. (Confirmed Below)
-023
Yoke: 2021111194 or 2021111201
"The early version is not compatible with either the Intermediate or latest versions due to the yoke being slightly different. If you use an early chassis on either one of the later ones, you'll get a foldover you can't adjust out as stated in the bulletin."
Service Bulletin:
"This bulletins applies to 4900 series monitors with serial numbers of 400001 and above. They can be identified by the following:
A) The model number on the monitor is printed in red.
B) The part number on the deflection yoke is either 2021111194 or 2021111201.
C) The flyback transformer stabilizing bracket is labeled 611X0005-008 (note: from my own experience this label always falls off so look all around inside the game cabinet and underneath the monitor main board for it).
D) There is an additional control, the VERTICAL DAMPING CONTROL immediately to the right of the vertical hold control.
NOTE: K4915 uses different Yoke than the above
Yokes with part numbers 2021111194 or 2021111201 are for use with early production run 4900 series and should not be used with this version chassis as insufficient vertical deflection, vertical foldover, or improper blanking will result."
https://forums.arcade-museum.com/showthread.php?t=38883
https://forums.arcade-museum.com/showthread.php?t=326143
https://forums.arcade-museum.com/showthread.php?t=142056
Last edited:


