I have been working on cleaning up a postwar Lionel set that belongs to a friend. Some testing on the model 1033 transformer revealed the DC signal that is overlayed on the AC track output, to operate the whistle tender, was all over the place. I have ascertained from much reading that the copper-oxide rectifier disk is probably bad. It seems to me that I should be able to replace this part with a modern silicon diode as a half-wave rectifier. Does this seem sensible? The transformer is rated at 90 watts but I'm not sure what the output of the DC signal is supposed to be. Any guesses on what size kind of current my diode should handle? Thanks for the help!
Should work. The beefier silicon diodes (larger case) ought to be good for an amp or two forward current and hold off 100 volts or more of reverse bias. I would expect just about any silicon diode in a large case to be strong enough to fill in for a copper oxide rectifier. Radio Shack should still carry diodes.
The DC output on the 1033 does have two levels - a higher "lifting" voltage, part way through the travel of the whistle control lever(to engage, or lift, the armature plate of the whistle relay), and then a lower "holding" voltage, at a slightly higher AC voltage (to compensate for the whistle motor running) so it sounds like the rectifier may be OK. The substitution of a silicon diode would work fine, two legs of a
4 to 6 amp full wave bridge makes for a neat install.
The replacement of the disc with modern parts is a common modification. I've purchased the correct size diode at train shows but I can't remember the number or specs. I'd suggest doing a search for Lionel parts suppliers and they would probably show the part on their website. S/V Express 30 "Ringmaster" "Trains are a winter sport"
I would go for the full rated output, which is somewhere between 5 and 7 amps. A 10 amp diode is not appreciably more expensive than a 5 amp one, so I'd go for overkill.
The design of the 1033 is such that the copper oxide diode is out of all circuits unless the left control lever is rotated to the "whistle" position. If you have DC "all over the place" when the whistle is not activated, it means: o The copper oxide diode is functioning as it is the only thing in the transformer that can produce DC, and o The contacts on the whistle switch are bent, the spring is not operating properly to return the switch to its normal position, something is bent or insulation is worn through causing a short circuit or sneak path, or the transformer was repaired by someone and incorrectly rewired internally. As others have noted, it is OK to replace the old copper oxide disk with a silicon diode, but based on the symptoms you report, you have another problem. The diode is switched into the circuit to the "U" terminal when the whistle lever is rotated part way, and then as the whistle lever is rotated the rest of the way to its stop, a shunt resistance is added around the diode to protect it from burning out under the full load current (this could be 5 or 6 amps on a steam engine with head light and smoke, both the propulsion and whistle motors running at full speed, a train of lighted coaches, and some track-powered accessories). Once the whistle relay picks up (Lionel's spec was that it should pick up on 1.1 VDC), it should be held up on as little as 0.5 VDC (which is the resultant DC with the shunt resistance in the circuit). Gary Q
"seware" wrote in message news:lc7xd.1245$ snipped-for-privacy@newssvr11.news.prodigy.com...
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