Zimo DCC info ?

Send them back to Zimo, I've had free repairs in the past. If you need to replace the PIC, where are you going to get the firmware?

MBQ

Send them back to Zimo, I've had free repairs in the past. If you need to replace the PIC, where are you going to get the firmware?

MBQ

+++++

Marked 2395 X002 on the overlay they are some sort of interface board, no PIC, only a 555 , one transistor and a number of diodes and passives and all those connectors. So far 2 have had duff lead-free soldering

cannot find reference to these boards on zimo.at

Has the same main connectors as this Bachmann E-Z Command 8 Pin To 21 Pin Adaptor

bit bigger board plus outlet connectors, labelled on board, for LED1, LED2, motor, R+ L- = rail pickups ?, Spk = speaker? and Aux1 which the output of the 555 via the transitor goes to

21 pinning seems to agree this

I've read the thread, and my opinion is that it's hardly worth the trouble, unless of course you want the "learning opportunity". Without a model number, it's nearly impossible to say what the board is. A later post by you suggests that it's a 21-to-8 pin adapter, not a DCC control board (decoder) as such. If, as you say, some of the solder joints are cold/defective, fixing them will likely fix the board. OTOH, if it actually a decoder, then most likely the chip is defective.

The DCC decoders convert rail power (14-18V, 50/60HZ) to chopped DC power (effective 0 to ca. 12V), and control other devices such as locomotive lights, sound systems, etc. The decoders include EEPROM which stores the control program, and "control variables", by means of which the board's (ie, locomotive) address can be changed, and functions such as speed control can be modified. The control is accomplished via data packages transmitted from the control station via the rails to the locomotive, at about 150KHz IIRC. Most of the control circuitry is integrated into custom-made packages ("chips", in model railway parlance).

You can find more at nmra.org, search for DCC. NMRA has specified recommended wiring harness colours, ie, pinouts for the board as a whole. The internal pin assignments for any chips are the manufacturer's responsibility/choice, of course.

You mention some on-board specs, I agree with your guess as to what they mean. That is, if the board is an adapter, and not a decoder.

I'm not an electronics expert, the above comments are based on my knowledge of DCC.

HTH Wolf K.

I went to Zimo's website:

There is an English version, accessible via a Union Jack in the upper left corner. In Firefox, the site displays badly (it has 14 errors according to but you should be able to find your board.

Good hunting!

Wolf K.

If you can't even the basics right about DCC, why bother posting?

Completely wrong again.

Need I say more?

MBQ

A picture of the actual boards would be more help.

MBQ

[snip] [snip]

AIUI, DCC puts a digital signal on top of an AC propulsion current. The latter is rectified to sine wave DC by the decoder, and is in turn chopped to provide average voltages below the maximum, thus controlling the speed of the locomotive. If this is incorrect, please elucidate.

The signal is delivered to the locomotive in the form of data packets, whose format is specified in NMRA Standard S-9.1. This standard also indicates that the propulsion current is AC, Vmax between 14 and 18V RMS.

My recollection of the propulsion current and the signal current relationship is that the former is "ordinary" AC, ie, 50/60Hz, depending on country, and the latter a high frequency, whose value I've probably got wrong, because I wrote from memory. Kindly correct and elucidate my errors.

Thanks, Wolf K.

No, the "propulsion current" and the digital signal are one and the same.

The DCC track voltage is a square wave digital signal and is rectified to DC in the decoder.

That bit is correct.

S-9.1 is the electrical standard. The voltage limits depend on other non-DCC scale specific standards.

Basic data packets are defined in S-9.2.

NO. "AC" does not mean 50 or 60Hz other than in the very limited definition of household mains.

The country is irrelevant.

You've hinted at the NMRA specs, why not read them for yourself?

The system you are describing is more akin to Hornby's Zero One, long since deprecated.

MBQ

[snip]

I did, that's how I interpreted them.

Thanks for the clarifications.

Wolf K.

Its not rectified at all its transformed into PWM feed to the motor the frequency can be varied on some decoders so that they can be tuned to particular motor types. Works the same way as DC PWM controllers.

The DCC signal is rectified to a DC supply in the decoder. Just look at a decoder and you'll spot the 4 diodes that form the bridge rectifier.

The DC supplies the microcontroller and the output H-bridge. The H- bridge is driven by the uC to generate the PWM signal.

MBQ