On Sat, 09 Jun 2018 18:04:23 -0700, you wrote:
I've checked some of the components to the schematic right of Q1404 (Q1408, R1406, R1402, etc, and randomly most of the nearby components), at least in-circuit for continuity. Determining if a component is open (rather than shorted) is a bit more complicated, and I haven't wanted to unsolder components indiscriminately. As stated earlier in the thread, the CRT circuit had been working until I accidentally must have shorted out something when I was looking at the low voltage measurements, so I'm not thinking it likely that a leaky capacitor or intermittent switch is the main culprit at this point.
Obviously my circuit skills are minimal, but I'm still bothered by the readings involving R1431, as given above. They seem so off to me, and since F1419 and C1419 _appear_ to be OK, my attention has been pulled to R1431. But if you feel that would not logically be the cause of my problem, then maybe I need to put more attention into the rest of the CRT circuit (all the components between Q1404 and T1420).
Actually, now that I am recalling my earlier blunder, I think what happened was this: while checking one of the low voltage supplies (don't know which one) I accidentally had my meter set for current instead of voltage (wrong button pushed). I remember hearing a strange sound, which may have been from loading the circuit, before I realized my mistake and disconnected. It wasn¡¯t until later that I noticed the trace had disappeared, and since there wasn't any smoke/drama I didn't realize until later that I must have burned something out. I'm guessing, in case this might help suggest a path forward.
If you were checking a power supply directly, then putting a meter on
current rather than voltage is likely to just short the supply to
ground. (how much depends on the current range and the meter).
You need to check all the supplies again, and then get an idea of
where you were measuring the supply. Many supplies have some
isolation components, a small resistor and capacitor to ground, a coil
wound on that resistor, perhaps even a fuse (maybe rare). See if you
can figure exactly where, and measure the voltage(!) there. It should
be within spec. You may have damaged one of the distribution
pathways, but not the main supply. That could take out power to a
specific section.
It's a common mistake to make. Remember that the voltage measurements
involve the meter looking like a very high resistance. When set for
current (and the leads are still plugged into voltage), the meter
looks as if it is not connected or as a very high resistance.
Generally, no damage except that which would happen if the power
supply is off.
For current, the meter is an extremely low resistance, so when
connected across any voltage potential, it generally looks like a
short. Expect the circuit to behave as if it were.
Harvey
I wish there was an easy way to check L1419 and T1420, but accessing or testing them easily eludes me.
Keith
Keith
