Subject: Solid State Music V1B question From: "Cini, Richard" <Richard.Cini at wachovia.com> Date: Fri, 15 Jul 2005 08:39:42 -0400 To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org> All: I'm playing around with the SSM V1B video board in my Altair, and I have a question about errata and board modifications, specifically with regards to the +12v power supply. I have three boards. One is "condition unknown" and two are working. The +12v regulated supply consists of a small-value series resistor, a zener diode and a cap. One of the boards has a 100 ohm, 1/4w resistor which is charred and when operated, continues to smell. The other working board has a 220 ohm resistor and the same zener diode and appears to work fine with no smell. The manual specifies a 100 ohm resistor and a 1N4742 diode. The "condition unknown" board has a 7812 regulator soldered to the pads replacing the resistor and the diode. From what I can tell from the schematic, the +12v is used only for the character generator chip. When turned on, I get a display full of well-formed garbage, which is probably just that it's displaying the random data in buffer memory. Does anyone have a view on what the best kind of repair might be? Thanks.