Hornby Class 50 R2350

[Chrissaf]

I understand that the 2 missing are SMD resistors both of the same value 221 which I take to be 220ohm but I am at a loss as to how to identify them completely.

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An SMD 221 is indeed a 220 Ohm resistor.

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Basically with SMD the first two digits are the number and the third digit is the multiplier (number of zeros to be added to the x1 multiplier).

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So

220 is 22 x 1 = 22 Ohms (zero 0s added to the x 1 multiplier)

221 is 22 x 10 = 220 Ohms (one 0s added to the x 1 multiplier)

222 is 22 x 100 = 2,200 Ohms (two 0s added to the x 1 multiplier)

333 is 33 x 1000 = 33,000 Ohms (three 0s added to the x 1 multiplier)

One of the most common SMD codes on LED circuits is 102

102 = 10 x 100 = 1,000 Ohms (two 0s added to the x 1 multiplier)

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There are many online calculators that will convert SMD codes to values, not just for resistors but for Caps and Inductors etc. Example SMD resistor / capacitor calculator.

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Also chrissaf pointed out an 8 pin JST connector which is a connector to board. Could you point me in the direction of a 2 pin in line connector in the same dimensions?

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I think I understand what you mean by 2 pin inline connector, I assume you mean a two part connector that forms a 2 pin plug and a 2 pin socket to allow inline connections to be made in the wiring away from the PCB.

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What I am not so clear about is what exactly you mean by "in the same dimensions"? Do you mean something that fulfils the inline connection requirement that is just physically small or do mean a connector that is exactly in the same style as the 8 pin JST connector.

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JST connectors primarily consist of a plug that mates with a PCB mounted header connector. JST connectors don't tend to be made in an "in-line" connector variety.

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If all you are after is a 2 pin "in-line" plug and socket connector that is physically small and the manufacturer or connector style is not that important, then you might consider these pre-wired ones:

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https://www.expressmodels.co.uk/catalogue/micro-connectors

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[50FAN]

Thanks chrissf for posting back.

Having read my post after posting yes I spotted the error.What I'm trying to achieve is what Hornby have done and get rid of the copper prongs which rely on pressure to supply power to the headcode light.Hornby have now hard wired this to there new lighting pcb via a 2 pin socket to board connector of which I will try and post the picture.I wish to use the old style boards and solder wires to the prongs via a twin in line plug and socket to two wires soldered onto the cab pcb.

Yes my comments were for being as micro as the 8 pin not its actual dimensions.Hopefully the photo will show the socket.

As for the SMD resistors it wasn't so much the capacity but the actual physical size to fit on the board.Having been on sites there seems to be a conversion to a relation in physical size like 0402 spec of dust through 1206 qfp44 huge.

Do I actually measure the the physical size of the resistor l x w

I will try and post some more photos hopes this explains.

Regards 

[Chrissaf]

If the PCB you have got has in essence the same style of socket as the 8 way JST ZHR-8 socket but is only two pins. Like this one below:

/media/tinymce_upload/86fe13ea16a13b99292106f291160a19.jpg

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Then the JST Housing that can be used to terminate on wires that will mate with that socket directly on the PCB are

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JST ZHR-2

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You will also need crimp terminals as the housing above is just the housing without pins. The pins 'usually sold in multiples of 100' are.

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SZH-002T-P0.5

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However they can be purchased in 10's at an inflated price on ebay.

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Yes SMD components have different codes for their size. For resistors, the larger the size then the higher the wattage. 1,000 ohm SMDs for LEDs don't need to be more than 1/8 watt (0.125W). This makes them resonably small physically. This web page will assist identification.

 

[50FAN]

Many thanks chrissafVery good info indeed.Will get onto this ASAP 

Regardd

[50FAN]

/media/tinymce_upload/b08d72d2a9b690fbb66af1d65c79fff5.JPG/media/tinymce_upload/19e656649260d15a1f1a0ed46852c10d.JPG

[50FAN]

Sorry back again.

Right have spent a bit of time on the site your post suggests but have ended up with more questions.Please remember that this is all completly new to me and have no idea.Having used the guide that you suggested I am now able to get the size.

0805/2012 metric 1/8 watt

My search was worded "smd resistors 0805 220 ohm 1/8 watt" which gave me a considerable list so i  applied some filters and these were

1. Thin film
2. 100v and 150v
3. The way in which it is supplied

This narrowed it down to about 8 items of which i was able to lose another 2 so left with 6 but that was as far as i could go.Attahced to list if you scroll over gives alot of other information of which i do not know

1. product range(does this matter)
2. Voltage rating(what would i need for a hornby pcb)
3. power rating(could you explain)
4. resistence tolerance(larger or smaller plus/minus 0.1% 0r 1.0%)

I can measure the physical dimensions of the resistor and that its an smd but theres nothing else to give its identity away.Is it possible to take a look at the photo above on the previous posts its the one missing at r10 and r9 if it is shown and are both the same physical dimensions of those surrounding it.As explained before I believe that this is the missing part of the circuit to get power to the headcode lighting and if this is the case I can then use the class 56 pcb and continue with the rest of the upgrade.

Thanking you

 

[Chrissaf]

Resistors are not really a critical component. Any resistor with the right values will do......they don't even need to be SMD type, they could be standard axial resistors if they will physically fit. I think you are over-cooking your requirements in trying to exactly match to the nth degree the missing resistor components.

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1. product range (does this matter)

Voltage rating (what would I need for a Hornby PCB)

power rating (could you explain)

resistance tolerance (larger or smaller plus/minus 0.1% or 1.0%)

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1) Product Range, does this matter - No not really. Components are made in different ranges to suit different circuit scenarios. Some components might have specific chemical make ups for different circuit tasks. For example, resistors can be made of carbon, carbon film, wire wound, and other materials. An LED circuit is what I would consider a 'general purpose' type of circuit application. So a 'general purpose' resistor range will suffice. These days 'carbon film' resistor range is considered the norm for most applications, but 'Carbon Film' tends to be in the larger axial resistor type. But this is not critical. 'Thin film' used on SMD resistors will be fine too.

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2) Voltage rating....resistors don't normally have voltage ratings the way other components like capacitors do. The circuit you are going to put them in is not likely to exceed 15 volts DC, so any rating that exceeds that value will do. SMD resistors being so physically small, could be prone to arching in 'high voltage' circuits and thus a voltage rating might be specified by the manufacturer for those higher voltage applications. But the voltages in a Class 50 PCB are not going to be at those levels. As I said, about 15 volts DC max.

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3) Power rating.......this is the amount of power (heat) the component can safely dissipate without burning up. For LED circuits the power rating can be as low as 1/8 watt, but 1/4 watt would give a safety margin in an average LED circuit. These are typical values in an LED circuit. To work out an exact power rating you would need to know the current passing through the resistor and the voltage drop across it and apply those values into Ohms Law (see mathematical formula below for calculating power in a DC circuit). See postscript at the end of this reply for a rough and ready calculation.

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Power Rating (Watts) = Current in amps squared times the Resistance in Ohms

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Power Rating (Watts) = Voltage dropped across the resistor times the current passing through it in volts and amps.

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Power Rating (Watts) = Voltage dropped across the resistor in volts squared divided by Resistance in Ohms.

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If we assume a current of 5mA through a typical LED, then 5mA = 0.005 Amps

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4) Resistance Tolerance......this is not critical in this application. Typically a tolerance of 5% or better will be fine. Based upon a resistor value of 220 Ohms, then a 5% tolerance would mean that the accurately measured value of the resistor should fall between 220 Ohms +/- 5% = from 209 Ohms to 231 Ohms

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For comparison a 1% SMD resistor at a nominal 220 Ohms should expect to have a value between 217.8 Ohms and 222.2 Ohms.

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For an LED circuit designed around a base 220 Ohm resistor, it would unlikely to be affected by even a 10% resistor tolerance [ 198 Ohms to 242 Ohms ].

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Postscript.

Based upon previous experience. Hornby PCB boards are likely to have a LDO (Low Drop Out) regulator on board to derive about 3.3 volts for lighting circuits. The advantage of a LDO is that it can maintain output voltage regulation when its input drops down very close to the output voltage of the regulator. This is key for DC Analogue layouts (say where the PCB is in a DCC Ready loco) as the track voltage is variable up and down. The LDO regulator maintains a near constant output voltage over a wide range of DC Analogue speed settings. This, of course, maintains the LED at a consistent steady brightness until such time as the controller speed is turned down to a really slow speed. This is not an issue when the DCC Ready loco is fitted with a decoder as the input voltage will always be constant at the max DCC track voltage level.

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This is consistent with the resistor values being low at 220 Ohms, they are probably only dropping about 1 volt across them when drawing about 5mA operating current. 5mA = 0.005 Amps

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From the Ohms Law formula for power rating a 220 Ohm resistor would only need to be 0.005 x 0.005 x 220 watts = 0.0055 watts from the Ohms Law formula Watts = Current squared times resistance.

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0.0055 watts is far less than 1/8 watt (0.125) so a 1/8 watt SMD is well within power rating safety margins.

[50FAN]

Oops a duplication in photos there could we delete one set?

Anyway once again a lot of good info there for me thanks for your time chrissaf.I did think about just using an axial resistor to connect the circuit but was a question more of aesthetics really trying to keep the board looking the same.

Anyway will get an order together for resistor and connectors and will report back findings when work is complete in a couple of weeks if not sooner.

Thanks again.

[50FAN]

Back home again after working away and have received my order which consisted of resistors and jst connector housings.Just to report that the completion of the circuit on class 56 pcb with the missing resistor now gives me power to headcode light so pleased with that.

Having ordered jst pin receptacles a few weeks back and also the housings i thought i was all set up to make connector blocks to convert wiring class 56 pcb to class 50 lighting pcb but i seem to be a component missing.The pins.

Sorry but i am going to have to call on you again chris for help.When i go to your link for pins it takes me to the receptacles not the actual pins,are the pins available?I have been on the site and cant seem to find them.

Your help again is much appreciated,thanks

[Chrissaf]

JST connectors only come in two forms.

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1. Plug housings for female terminals.
2. The male pin JSTs only come in PCB mounted headers, as I detailed in my previous reply on page 3 of this thread (two pin PCB header with male pins shown).

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JST do not make free flying lead based sockets with male pins. In other words you cannot use JST components to make inline male / female connections. JSTs are made and marketed by JST as PCB header connection componetry.

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This, of course, does not stop you soldering wires to the tags on the PCB male header sockets with a bit of 'heat shrink insulation' to use them in a non-standard manner as a home made inline connection socket with male pins.

[50FAN]

Ok thanks understanding that now.Will have a look at that then.

Thanks again

[50FAN]

Hello again

Right after a while experimenting with jst stuff i have finally sorted an in line connector of which i will post a photo over weekend.The clips and receivers are really hard to work with and would actually like a set of crimps but cant seem to find any for the size involved and I am crimping by hand of which I am not happy with.Anyway just a quick question on the back of this.

Does anyone know the gauge and type of wire actually used by Hornby in what i should imagine would be all their locos?

I am using a 30awg 7 stranded tinned copper wire silicone coated.

This still seems too big and I believe Hornbys to be just PVC coated.

Can anyone shed some light,and on the crimps!

Thanks 

[Chrissaf]

When you say crimps...do you mean crimping pliers specifically made for the tiny JST crimped connectors. Yes they are made, but are extortionate prices because they are deemed as only being used by commercial companies. I use those JST crimped connectors a lot. I have tried several different so called JST crimping pliers that have been advertised as JST compatible in the £20 to £30 price range and have yet to find one that really makes crimping the connectors effortless. The only genuine JST crimping pliers I could find were nearer £60 to £100. I don't crimp enough connectors to make that expense worthwhile. I have ended up getting the best results by crimping them by hand manually using miniature 3 3/4" pliers with very pointy fine slim tips - see photo.

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The very short pointy fine pliers tip allow me to really get a good grip on to the tiny metal tabs on the JST terminal sockets and pins. Pliers in this specification are like hens teeth....I have looked before for a new replacement.....I have had mine for years and have no idea where I got them from.....they are marked with a "CREM" brand name (which does not get any hits using Google).

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/media/tinymce_upload/5852351095e037fa297f6bb5ac1df4e1.JPG

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Don't forget that images posted over the weekend won't be approved until next week....and may be delayed further than that as there is no new Administrator permanently in place to approve them. See the post titled "Forum Administration - UPDATE" in the 'Forum & Website feedback' forum.

[Chrissaf]

You could consider this wire:

https://wicknessmodels.co.uk/product/fine-decoder-wire-choose-colour-quantity-copy/

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A very cheap alternative is to strip the wires out of 8 way burglar alarm cable. The cable, thus the wires are very thin and the wires are stranded conductors. The added benefit is that unlike telephone cable (see below), alarm cable uses very nearly the same standard decoder solid colours for the eight wires.....red, black, yellow, white, green, blue, orange ......but brown instead of grey. Typically 7 x 0.17mm or 7 x 0.2mm strands per wire.

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Do not use telephone cable, this cable uses solid 0.63mm diameter conductors in the wires and a striped colour scheme on the wire insulation [i.e. blue/white, orange/white, green/white, brown/white, slate/white etc]. Being solid conductors, the wire is relatively stiff and subject to fatigue induced breakages.

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[50FAN]

Thanks for your input again Chris.

And for reminding me about photos i've learnt my lesson on that one.

As you will see in photos,yes i have been down the route of the so called jst crimpers,fine for heavier gauge connectors.Due to space restrictions/keeping it tidy i must be on the smallest connectors jst supply.I did however manage to make a straight in-line connector using jst stuff,it took a while but it helps if you read their data sheet, saves a lot of time.

The reason I ask about cable is that also I have been down the route of the alarm cable(ditched the telephone and cat 5 straight off).It is a fine stranded cable for sure but as you may or maynot see in the photo still a couple of gauges bigger.Also in that photo you will see 3 cables, top is alarm second is 30awg silicone sleeved and thirdly Hornby original.

As you can see the alarm cable is is pretty large.So looking at the other 2 I would presume Hornby original is 32awg and PVC coated.I don't mind the 30awg but being silicone,its flexible but wont bend at a 90 degree and stay there it wants to curve its way round and if you know the wiring on the fifty and maybe others they are put into some tight channels.So hence the reason for sort of an exact match.

Anyway for anybody wishing to use an inline straight jst connection these are the codes,trust me i've done the homework.

Housing ACHTP-02V-S

Crimp SACH-P003G-P0.2

Housing ACHTR-02V-S

Crimp SACH-003G-P0.2

So I will post back when I've completed the original task.

Going to upload photos in seperate post

Thanks again.

[50FAN]

photos showing crimps,cables,male/female connectors and completed connector/media/tinymce_upload/da20d5bcdd69d2166bd3c6aaa11784dc.jpg/media/tinymce_upload/83666d234234765bb8174b9abe36610a.jpg/media/tinymce_upload/3f4e620b88bea57ff47b48fd6b66cd9a.jpg/media/tinymce_upload/721bdd19bf5b729213424d0d54c78f6a.jpg

[50 FAN]

Hi 

Ok its been a while and I am back on trying to get to the botoom of the Hornby Class 50 PCB problem that I have and no doubt will be calling on chris and his expertise in this field.

I have many Class 50 PCBs that have this issue but for the example and photos I will use the first generation PCB with axial componements.

I have wired this PCB directly to the supply, in other words taken out the bogie pick ups to eliminate a bad connection from them.I have also taken out the motor being connected to the PCB as I believe this plays no part.

So we have a PCB with power supply to both ends and the directional lights PCB at eithier end all wired correctly.I have varying problems on boards but I believe to be caused by the same issue.

Problem 1

Setting controller to forward direction the white high intensity light should light in the forward pcb and the red marker lights should light in the trailing pcb.

What happens

Setting the controller to the forward direction both the white and red lights light in the forward pcb and both the white light and red marker lights light in the trailing pcb.

As the power is increased the PCB goes into normal operating condition.Unfortunatly this ,means in order to have it working as it sould the loco would have to run at race speed.

Problem 2

Really more of the same except this only happens in one direction.In other words going forward will light white and red at the forward end and red at the trailing end and when direction is changed ,lights white correctly and red correctly to its following end.

There are not many different components on this board,resistors/capicitors and transistors.Would I be correct in assuming that this would be a transistor not doing its job?

I will post photos in another post.

Many Regards

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[50 FAN]

/media/tinymce_upload/c1261be78835031f9ae893c90ce7cc62.jpg

All lights lit both ends in forward direction at low controller setting/media/tinymce_upload/6b914bbc831a365351c5d62bfa4a36d6.jpg

Turn the controller up and works as it should/media/tinymce_upload/c21be1ba868c7a2483d5bfc5ffffd8d2.jpg

Change direction low power and same all lit/media/tinymce_upload/225758df685cd770f080bdd0e0d35018.jpg

Increasing power again and in the reverse direction and lights as should

[96RAF]

Makes me wonder if one is common positive and the other common negative for the lights. Some 21-pin 56s were opposite polarity to the 8-pin versions.

[50FAN]

Hi

I must explain that this is on dc.Its wired up as it was supplied and by examining other 50s in my possesion.I dont claim to understand PCBs and I am trying to self teach.What a head doer.

Anyway if you could enlighten me with the common positive and common negative board thing and how this would affect the lighting and a solution to try then that would be great.After reading up about diodes I am beginning to wonder about these especially with the increase in power thing.

Many regards.