How do I revert back from DCC to Analog on an LGB F7 loco?

I agree with your systematic debugging Dave, and I hope I did not insult your intelligence with my "start at the beginning" suggestions.

Interesting that the decoder in the A unit could affect it, since it would appear that the "stock" configuration the decoder in the A unit does not "touch" the speaker.

Is possible that someone has altered the stock configuration, and re-wired the lights and A unit speaker, even possibly change the decoder?

I guess this will all come to light (no pun intended) when the A unit is opened.

Regards, Greg
 
Here you go:





Again, from memory:
Three screws along each side, and a couple horizontal into the back.. I *think* the front 'hooks-over' a stub on the chassis.
I have not had one apart for a few years!

<edit> You might need to 'spring' the body towards the back-end?? Handrails, I think???

PhilP.
 
HI Dave,

What is the specific model number of the F7A and B units you are having trouble with? This information will help pin down the age of the units. More specifically whether they had older MTS On-board decoder/sound decoder that were supplied to LGB by Massoth or the newer Märklin mfx/DCC multi-protocol decoder installed. I'm assuming these still have their original factory installed decoders.
 
Greg Elmassian said:
So the 4 wire cable carries the sound, the 2 wire cable the power, and you have to have the B unit turned in the correct direction. Hard to believe the stock decoder can effect the sound from the B unit.
Click to expand...
Even weirder - The sound required the B unit to move.. Whether it was a wheel sensor, or motor/BEMF, I don't remember.
 
I had a problem recently with my LGB A-B set, the standing sounds had stopped working. After some fault-finding the fault was traced to the 3 position switch on the back of the A unit. I fortunately had a stand-alone A unit so I was able to swap the rear panels as a complete unit between each loco.

As a reminder to those that are not too familiar with this LGB A-B set, the B unit only contains the sound board and a wheel sensor. It has no motors or lights.
The 4-way cable must only be used for sound. 2 wires for loudspeaker and also a wire (or 2) from the loco decoder to trigger F-key sounds.

The body of the A unit is attached by 3 screws each side, 2 screws at the ends and a single screw central at the front. There is another pair of screws at the front that appear to fix the body but they only attach a small infill piece.

In the process of swapping the rear panel, I pulled a wire out of the tiny 2-way/3-way plug that connects to the decoder board in the A unit. The lesson here is be careful!

The 3-way switch has 1 common and 2 n/o contacts. The outputs can then be switched on progressively.

If I remember the selections are -
-Loco totally off
-Lights on
-Lights, motors and sound on
The settings apply whether you are on DCC or DC.

Are you sure that the switch is in the correct position?
Or is it a faulty switch?

If I remember correctly (I can't remember what that means !!!) I resolved the switch problem by linking all the switch pins together.

Alan
 
Concerning the sound. The B unit has the sound and it can drive 2 speakers. Both A units in the ABA config, or the both A&B units in the AB config, but the volume control must be at the rear of the combo, not between the A and B unit. ALso if it is an original LGB/Massoth decoder that one must use a DCC system and write CV 55 to 55 to reset the decoder which will give address3 and 14 speed steps. If it is a different manufacturer this will not do a reset. Note that if CV 8 is read first, LGB code is 123 for the manufacturer (LGB/Massoth).
Also note that now Marklin is making F7A units that contain all the electronics including sound, B unit no longer needed for sound!! New B units just have a speaker, no electronics!! ANd the cables are different thus avoiding issues/problems mixing old and new F7 systems.
 
Dan said:
Concerning the sound. The B unit has the sound and it can drive 2 speakers. Both A units in the ABA config, or the both A&B units in the AB config, but the volume control must be at the rear of the combo, not between the A and B unit. ALso if it is an original LGB/Massoth decoder that one must use a DCC system and write CV 55 to 55 to reset the decoder which will give address3 and 14 speed steps. If it is a different manufacturer this will not do a reset. Note that if CV 8 is read first, LGB code is 123 for the manufacturer (LGB/Massoth).
Also note that now Marklin is making F7A units that contain all the electronics including sound, B unit no longer needed for sound!! New B units just have a speaker, no electronics!! ANd the cables are different thus avoiding issues/problems mixing old and new F7 systems.
Click to expand...
Depending on which F7A unit it is, reverting to analog once you have the body off should be as simple as removing the decoder (s) and setting the DIP switches the opposite way. I recently converted 2 of my analog F7s to digital. One of them with 2 LGB 55021 decoders and the other with a single Massoth LS decoder. It was very easy to do. You could probably even sell the decoders if you have no planned use for them.
 
Distrackted said:
Depending on which F7A unit it is, reverting to analog once you have the body off should be as simple as removing the decoder (s) and setting the DIP switches the opposite way. I recently converted 2 of my analog F7s to digital. One of them with 2 LGB 55021 decoders and the other with a single Massoth LS decoder. It was very easy to do. You could probably even sell the decoders if you have no planned use for them.
Click to expand...
Sorry, in my previous post I said Massoth LS. Should have been XL.
 
That is a lot of great information! I want to thank you all for your input. I will work on your suggestions and report back. Thank you!
 
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