pheaton

If the decoder has a speaker or wires already attached then no soldering is needed to the board... So if your 21pin ESU or ZIMO has wires on it you can solder these to a speaker in the case of the ZIMO or...Change the speaker (if you want to but trust me you will) in the case of the ESU. But to confirm no further modifications are required to main circuit board. If...the decoder you install has no wires or speaker...then you have 2 options, as your 66 is 21 pin it may already have pads or connectors for a speaker in which case solder your speaker to those pads...if your 66 does not have those pads or connections you will need to use the wiring diagram provided with the decoder (you can download these from the ZIMO or ESU websites) and trace the pin to a convenient location on the board and solder the speaker in there. However if you get into difficulty then you have come to the right place Let us know how you get on.

Hi Paul, Glad i didnt offend I did base my assumption on the 2 21 pin zimo's ive just bought which didnt have the wires they were just the basic chips, i knew the 20s they were destined for had speakers soldered to the board so i knew it would be an easy situation. Thanks Simon

Paul, i wasnt making judgement on the brand, but the overall job.... An ESU decoder being pre-wired with a speaker would be far easier to wire a speaker to then a zimo, would you not agree? similarly in a 21pin scenario you can solder to the board, but in a 8pin scenario you need to solder to the chip....i would personally find it easier and less costly in the event of a mistake to solder to the board, rather then the sound decoder. The point i was getting at was that a 21 pin locomotive would be easier to fit sound to due to the connections on the board. In an 8 pin scenario a pre-wired ESU decoder makes the job easier because they are already fitted, however im sure a steady hand and a fine soldering tip will suffice when soldering to a zimo...but obviously thats £70-80 quid chip that some stray solder could cause some trouble with. Of course if ZIMO 8 pin chips come with speaker wires pre-soldered then i am happy to put my hands up and say im wrong but as far as im aware they dont? Thanks Simon *edit in light of pauls post, yes i entirely agree that ESU supply a speaker which i do throw away, but into bargain i get two handy wires to solder the new one to. People with the incorrect iron tip and/or not surface mount solder trained will find it quite difficult to solder a speaker to a non pre-wired chip regardless of the brand.

All of my Bachmann OOTB locos with sound have it supplied from the circuit board, as far as im aware the OOTB sound locomotives have a modified board to cope with this. The older Bachmann loco's as far as im aware dont cater for it, and only newer released NON sound locomotives have had the boards modified to cater for it...... Likelyhood is that 66 being 8 pin will not have the connections on the board. I have 66022 which was OOTB fitted with sound but thats 21 pin and as far as im aware the board was modified to accept the speaker.... Bear in mind that Bachmann had to re-tool the chassis block on a OOTB sound loco to cater for the modified circuit board and speaker space, so older locomotives generally dont cater for this function off the board as they will have the older chassis block. If you buy an 8pin ESU sound decoder from a supplier like howes or SWD they come with a speaker wired to the decoder when i fitted two of these to my HST power cars i unsoldered the speaker at the speaker end and just soldered the wires to the replacement bass reflex. So thats quite an easy situation. Ive not yet purchased a 21 pin ESU decoder so i cant comment on that but since im pretty certain your 66 is 8 pin so if you chose ESU you should be ok, but dont take my word for it check to make sure its 8 or 21pin. If you want to buy a ZIMO as far as im aware you have to solder the speaker to the chip or your board, you should be able to see this on the zimo manual. You can solder it to the board providing you can trace the pin outs to a particular wire on the board as 2 of my Bachmann class 20s are fitted with 21pin zimos and i have used the Bachmann speaker outputs on the main board. Which simply connect to two of the pins on the decoder. But as paul rightly says if your loco is 8 pin you will have to solder the speaker to the chip. So it all depends really on the decoder you chose as to how difficult/easy the job is. *edit paul beat me to it...the only thing i would add paul is Bachmann seem to stick to 8 pin for non sound 20s early 37s and 66s. Hornby seem to follow a similar mantra my 56s 31s and 50s with sound are all 21 pin yet my non sound 50s 31s and 56s are all 8 pin....