It all depends upon the Wei-ya chassis model number. You have to know some specs of the yoke and tube you're going to use and select the appropriate universal chassis:
Low impedance yoke, 10 pin (29mm diameter) tube neck, requires isolation transformer. Model 1220-H for 19" tubes.
Low impedance yoke, 8 pin (22.5 mm dia) tube neck, requires isolation transformer. Model 1220-S for 19" tubes
High impedance yoke, 10 pin (29mm dia) tube neck, requires isolation transformer. Model 820-H for 19" tubes. Works well to convert an Atari Disco standard resolution monitor.
High impedance yoke, 8 pin (22.5mm dia) tube neck, requires isolation transformer. Model 820-S for 19" tubes.
Low impedance yoke, 10 pin (29mm dia) tube neck, does not need an isolation transformer. Model 2620-H for 19" tubes. Model 2420-H has a contrast control.
Low impedance yoke, 8 pin (22.5mm dia) tube neck, does not need an isolation transformer. Model 2620-S for 19" tubes. Model 2420-S has a contrast control.
High impedance yoke, 10 pin (29mm dia) tube neck, does not need an isolation transformer. Model 2820-H for 19" tubes.
High impedance yoke, 8 pin (22.5mm dia) tube neck, does not need an isolation transformer. Model 2820-S for 19" tubes.
Add a "-R" suffix to any of the above model numbers if you want a model supplied with a remote adjustment board. They normally have all adjustments on the monitor main board.
Remember, the yoke wiring and connector pinout of the Electrohome monitors is different than other monitors. The yoke wiring must be modified first to conform to the new universal monitor chassis or else both the yoke and new chassis will be destroyed immediately upon power up.