Hey guys thanks for the posts. Realize that in the first post some of the 'problems' with the units are intermittent. For example, the one that blows bulbs is adjusted right to spec at 80.0 v and the few other voltages on the schematic are in spec. Bob-D659, on that board, BTW I did find a cold solder joint on the connector leading to the lamp. I also put in a fresh TRIAC, and saw that the old one was not making good contact with the heat sink. I used that board last night and no blown bulbs so that board may have had its life-span extended.
The schematic does not give any useful voltages or document appropriate signal behavior. In terms of the service manual, the board is treated as a 'replaceable item.' Another issue is that access to the board is very limited once it is in place in the head. Extended jumpers and 'breakout' boards would need to be constructed to do any major diagnostics to this board. I did look into turning my 'spare parts' head into a test dummy just to test this board as I agree with you all the it is probably some 5 cent part that is amiss, however, constructing a 'test head' would be quite a project in itself.
As I stand now the 'spare' board is already stripped and IC sockets are in. So once the parts arrive I just need to plug in the ICs and add the few resistors and caps.
Last edited by ic-racer; 03-11-2009 at 01:58 PM. Click to view previous post history.