captouch
Addicted Member
I bought some replacement lamps (14V, 80mA) for my CR-220, which has a meter light out and the dial light on the pointer is dim.
Well, when I looked inside, someone had cut and spliced the two lamps to different voltage sources and neither of them are 14V anymore.
The meter lamp is being fed by a 20V supply, and the dial lamp is being fed by a supply that's 6.5V or so (I guess that's why it's dim).
Looking at the schematic, these lamps are supposed to be fed by L1/L2 and L3/L4. See green boxes in attached picture.
I can see cut wires on L2 and L3, no longer being used.
When I probe voltage between L1/L2 and L3/L4, I get 20V initially, but the voltage bleeds down to zero over time.
I thought perhaps a leaky cap, so I desoldered the cap in red box that is common to L2/L3 and put a new cap there, but I still get the 20V initial and bleed down to zero.
Any idea what's going on?
Whoever was in there before must have found a stable 20V supply and connected the meter light to that source, and found a lower voltage supply for the dial lamp.
I am thinking that trying to use 14V lamps with a 20V source is a bad idea and I'll burn them out (if not immediately, then quickly).
So ideally I'd like to find out why the voltages aren't correct on the Lx terminals and why they're bleeding down just by my measuring them.
Any ideas on where to check next?
Well, when I looked inside, someone had cut and spliced the two lamps to different voltage sources and neither of them are 14V anymore.
The meter lamp is being fed by a 20V supply, and the dial lamp is being fed by a supply that's 6.5V or so (I guess that's why it's dim).
Looking at the schematic, these lamps are supposed to be fed by L1/L2 and L3/L4. See green boxes in attached picture.
I can see cut wires on L2 and L3, no longer being used.
When I probe voltage between L1/L2 and L3/L4, I get 20V initially, but the voltage bleeds down to zero over time.
I thought perhaps a leaky cap, so I desoldered the cap in red box that is common to L2/L3 and put a new cap there, but I still get the 20V initial and bleed down to zero.
Any idea what's going on?
Whoever was in there before must have found a stable 20V supply and connected the meter light to that source, and found a lower voltage supply for the dial lamp.
I am thinking that trying to use 14V lamps with a 20V source is a bad idea and I'll burn them out (if not immediately, then quickly).
So ideally I'd like to find out why the voltages aren't correct on the Lx terminals and why they're bleeding down just by my measuring them.
Any ideas on where to check next?