I am working with a friend that is using a PM 42 as an auto reversing unit but we are having trouble getting all 4 sections to work. The number 1 slot trips and holds OK but none of the other 3 will hold. We can see the LED switch and here a click but them it switches back. How and what do we want to change?
Dan: This is a review of the PM-42 by Tony's Trains. In the last two paragraphs, the problems with getting the unit to function properly are discussed. Hope this helps you out. DIGITRAX PM4-2 The PM42 is a 4 section, mechanical relay, user configurable, autoreverse and/or circuit breaker module. It requires programming with a Digitrax throttle, considerable pre-planning and moderate soldering skills of many wires. The PM42 is the same as its predecessor, the problematical PM4, except it has a firmware (chip) update to allow the user more necessary control over autoreverse and circuit breaker switching times. The PM42 is a difficult product to integrate into the average dcc layout. The PM42 circuit board plugs into a 44 pin dual edge connector. The connector's holes are smaller than the wire sizes Digitrax recommends for installation. This requires the user to fabricate 'necked down' connections, going from the bigger gauge wire to short lengths of a smaller gauge wire so they can fit into the connector's solder holes. The results can be ugly, time consuming and difficult for most users. This becomes extremely difficult when more than one wire must be soldered or 'daisy-chained' into each tiny connector hole, as is the case for configuring the PM42's four sections. Patience and moderate soldering skills are required. The PM42 requires a separate, unshared AC or DC 125mA minimum output power supply - the only product of its kind to require one. The only device that Digitrax recommends can share a PM42 power supply is another PM42 and only if the power supply puts out sufficient current for two or more PM42's. Some users share the PM42 power supply with Digitrax block occupancy detector modules but, Digitrax tech support frowns on this practice. The PM42 also requires a heavy gauge ground wire between itself and the Digitrax booster for proper functioning - the only product of its kind to require one. Each of the four sections of the PM42 can be independently configured either as an autoreverser or circuit breaker but, not both at the same time in one section. Unfortunately, configuration requires that the 44 pin edge connector be permanently soldered in such a way as to create an autoreverser or circuit breaker section. These 'hardwired' settings are permanent in nature and changing them can be difficult or impossible for any user. Additionally, a Digitrax throttle must be used to program specific option switches to complete the autoreverse configuration of any given section. All four sections are equally affected by the circuit breaker current setting, which can be set between 1.5 and 12 amps in 1.5 amp steps so, they are not independent in that regard. As an example of its configurability, one section can be used as a circuit breaker to protect up to three other sections set up as autoreversers. Or, any combination of four autoreversers and/or circuit breakers can be configured using one or more boosters as input sources. Each section, whether configured as an autoreverser or as a circuit breaker has independent switching time selection. Four user-selectable switching times can be set by programming the module with a Digitrax throttle. This process is not adequately explained in the Digitrax instructions. Typographical errors and conflicting recommendations for timing settings plague the poorly written instruction manual. Unfortunately, following the instructions and setting the PM42 to its lowest 1.5 and 3 amp current levels causes problems for the average user because the PM42 has a distinct tendency to oscillate and switch unpredictably at these lower current settings. Even at the higher current levels of 4.5 amps and up, the average dcc user will have to 'tweak' his layout wiring and option switch timing settings to get the PM42 to work satisfactorily. If the switching times are incorrectly selected with the option switches, and that's easy to do under the circumstances, autoreversing action and short circuit protection can be rendered completely inoperative. The PM42's only claim to fame is that it 'reports' the status of each of its sections to other devices on the Loconet network or to a pc running layout automation software. The PM42 offers you a four-section product which works fairly well after tedious installation and tweaking of the layout. I wouldn't recommend it to anyone except a 'hardcore' Digitrax user, based upon the difficulties I've had with mine. Stay cool and run steam....
OUCH!! That's harsh! The PM42 does have a number of options which interact and must be properly configured, but it's not rocket science. You didn't say if all 4 sections of the PM42 are to be used as auto-reversers. Each section can be set up for short-circuit protection, in which case it will automatically reset after a second or so, OR as an auto-reverser, it which case it "sticks" until triggered again. If set as an AR, no short circuit protection is provided (you will need your booster or another PM42 section to do that). It sounds as if section 1 is set for auto-reverse, while sections 2,3 and 4 are set as normal circuit breakers. For auto reverse in sections 2,3 and 4, OpSws 14, 22 and 30 respectively need to be closed, and the Rev A/RailA and RevB/Rail B jumpers need to be installed on the edge connector. As the reverser is tripped by the short circuit that occurs when a tran crosses an out-of-phase gap, it is important that the AR sections are set for "faster" trip speed, otherwise, whatever is doing short circuit protection may act before the reverser trips. OpSws 3/5, 11/13, 19/21 and 27/29 do that.
All 4 sections will be used for auto-reverse. I will check those OpSws and the fast trip settiong. I know that the jumper is installed on all for section. We did that on the bench. Can some one give more info on the programing of this unit. The book is confusing at best.
