19-05-2015, 05:22 PM
Be careful - don't risk putting additional faults on it just yet 
At the risk of stating the obvious, it might not be a case of the rail being pulled down - rather, the power supply might have a fault. As mentioned, it is unregulated, so you'd expect the rails to be only approximately correct anyway. There are a lot of electrolytic capacitors in the power supply that could be faulty, and that would give low output. Once the scope is sweeping, you'll be able to use it to check the power supply rails to see how much ripple is present - right now, a DVM is not the best tool for that job.
At the risk of stating the obvious, it might not be a case of the rail being pulled down - rather, the power supply might have a fault. As mentioned, it is unregulated, so you'd expect the rails to be only approximately correct anyway. There are a lot of electrolytic capacitors in the power supply that could be faulty, and that would give low output. Once the scope is sweeping, you'll be able to use it to check the power supply rails to see how much ripple is present - right now, a DVM is not the best tool for that job.
