[drh4683]

Great find! Those are great portables! The 15YC615 is from 68 and went to 69. Ive got both models that they made. Ive done a bit of work to both of them, and yes, Ive experienced tint range problems with one. Basically, the control was all the way in one direction to get a normal looking flesh tone. That was corrected by placing the tint control in the mid position, and adjusting the slug in the burst amp plate coil untill the flesh tone looked correct. Thats the simplest way. Mine also had a problem with the color killer circuit. Couldnt get the color to kill regardless of the setting. Turned out to be an open crystal diode in the killer circuit. Yes, the 15YC615 has a 6GH8 for the 3.58 osc./reactance. Check it for shorts! We cant say enough how bad the 6GH8 is! The most trouble prone tube ever!
As far as focus, these sets natrually have a soft picture, even when focus voltages are correct, and the crts are in great shape in mine. Dont feel bad about the picture, thats just the way they are. The latter models had an efficiancy coil in the horiz. circuit so you could adjust the regulation. On the earlier runs, adjusting the 21.5 kv is the only way to set the reg.
Here is the proper way to adjust hv on the 15YC615:
warm the set up for a few minutes
color all the way down
set up switch in "set up"
test the line voltage at the plug. For every volt less than 120volts, subtract 80volt from the HV reading. So, if you read 117 volt, you need to take off 240 volt (80volt x 3) from 21.5 kv, making an adjustment of 21.260 nessisary.

Your set may or may not have the efficicancy coil. You will see a shorting clip near the horiz. out tube. Remove it, insert a mA meter across those two terminals (0-300 mA scale) and adjust the efficiancy coil for minimum reading on meter. The coil is located behind the HV cage (tward the front of the TV) Easiest way of adjusting it is to remove the bottom cover and adjust.

Pictured is the burst amp plate coil, its just beneath the right side of the delay line in the photo. Adjust that for proper tint.

Next pics are the 2 portables with the 15YC615 chassis. These are the only two styles they made, so yours must look like one of these. The last one pictured is the one that gave me most trouble. Found that one on the curb 2 years ago. Main problem was a shorted filter cap, then it was downhill from there with problems. Now its fixed so it works pretty darn good now.

The other one (gold cabinet) worked when I found it, and needed nothing but tubes in various places.