Hi,
I'm a newbie on this forum and I was hoping someone can help me with a power supply problem in a Heathkit Super Clock GC-1195 w/chimes.
I built this clock in 1976 or thereabouts and has been very reliable. I had to replace D101 & 102 (which are 2 diodes in the bridge) in 1987 for an intermittent condition. The original diodes had a forward current rating of 2A and a PRV of 1000V. I replaced them with ECG 5802 which has a forward current of 3A but only a PRV of 200V. I didn’t think that the lower PRV would be a problem because it’s only an 18v power supply. I guess I was correct in my thinking because they lasted for 20 years! Now the diodes opened up. I bought new ones today, ( 1N5404) which are rated at 3 amps and 400 PRV. I put them in and the clock works great except the diodes seem to run excessively hot! The B+ at the filter is at 18 volts just like it should be. There are some + or - 1 volt variations depending on how many bulbs are lit, but even at 1:11 O’clock with the bulbs dim, the diodes still seem to run too hot.
This is where it gets a little heavy! In 2001 I replaced all the bulbs with E5 screw base types because the wedge base bulbs were so problematic. I replaced all the wedge sockets with screw type and used T - 1-3/4 midget screw bulbs which are rated at 6.3 volts @ .2 amps. The originals were 5V @ 120 mA T-1 Wedge. Orginals are 5V x .12A = .6 watts. The replacements are 6.3V x .2A = 1.26 Watts. I thought that was my problem, but like I said before, it can be at 1:11 & dim and the diodes still run hot.
Anybody have any ideas?
Thanks,
Jim A.
I'm a newbie on this forum and I was hoping someone can help me with a power supply problem in a Heathkit Super Clock GC-1195 w/chimes.
I built this clock in 1976 or thereabouts and has been very reliable. I had to replace D101 & 102 (which are 2 diodes in the bridge) in 1987 for an intermittent condition. The original diodes had a forward current rating of 2A and a PRV of 1000V. I replaced them with ECG 5802 which has a forward current of 3A but only a PRV of 200V. I didn’t think that the lower PRV would be a problem because it’s only an 18v power supply. I guess I was correct in my thinking because they lasted for 20 years! Now the diodes opened up. I bought new ones today, ( 1N5404) which are rated at 3 amps and 400 PRV. I put them in and the clock works great except the diodes seem to run excessively hot! The B+ at the filter is at 18 volts just like it should be. There are some + or - 1 volt variations depending on how many bulbs are lit, but even at 1:11 O’clock with the bulbs dim, the diodes still seem to run too hot.
This is where it gets a little heavy! In 2001 I replaced all the bulbs with E5 screw base types because the wedge base bulbs were so problematic. I replaced all the wedge sockets with screw type and used T - 1-3/4 midget screw bulbs which are rated at 6.3 volts @ .2 amps. The originals were 5V @ 120 mA T-1 Wedge. Orginals are 5V x .12A = .6 watts. The replacements are 6.3V x .2A = 1.26 Watts. I thought that was my problem, but like I said before, it can be at 1:11 & dim and the diodes still run hot.
Anybody have any ideas?
Thanks,
Jim A.
Last edited: