Honda CX500 Motorcycle CDI ignition unit

[redwire]

I got stuck finding a waterproof box, finnbox appears to be 120x80x30mm and all I could find in North America is way thicker like 55mm. The next size down, smaller enclosures I couldn't fit all the parts on a pcb.
Looking at Bud PN-1323 or Hammond 1554F the 1554C is too small. Let me know what you think.
I can make a board made once I figure out the box size and thankfully the heat wave ended. I don't care about a few bucks for parts.

The other R21 that connects to R20 (220R) is 910R?

[stj]

https://www.aliexpress.com/wholesale...of+project+box

[redwire]

Stop making me laugh
Sort by size - haha 5,610 results fu
"waterproof" - no gasket lol avoid puddles
Comes with screws? - no
Dimensions drawing - not available
recycled plastic - maybe

It's chinese torture. These boxes come in standard sizes, all are way too thick over 2-1/4" 55mm.
For some reason the prices are actually the same through distributors, I wonder why the price is up there.
I did find the usual 115x90x55 though and only one box is slimmer but it looks a bit um uh low quality and reviews complain the plastic is hard and full of voids.

[stj]

why not a cast or extruded aluminium box?

[roadrash]

Thanks very much for all your doing for me. Just had a bad time last few days as I lost my mother due to a blood clot in her heart. I Will be back on in few days.

[redwire]

My condolences on your great loss. I lost my mom suddenly years ago and I feel it was better than seeing her suffer slowly from some crappy illness.

Working on the project, best I could do is a PC board for a common 115x90x55mm box. Just too thick for my liking. Please advise if it will fit.

Best box (pic) is one Aliexpress box low profile but I don't know how long the boat ride would be.

[Per Hansson]

Condolences for your loss!


A small idea about the box if you haven't already considered it is a custom 3D printed one.
Many places you can order 3D prints from models you provide...

[stj]

noooooooo......
you cant use thermoplastic on a bike - it will soften or melt!

[redwire]

The module is located underneath the seat, away from the engine.

ABS rated -40°C to +80°C, no sunlight, I was using this it's low cost.
Polycarbonate rated -40°C to +120°C, UV is okay
Aliexpress rated nothing, melts if you look at it.

pic is of what the low profile finnbox looked like.

[roadrash]

Originally Posted by redwire

The module is located underneath the seat, away from the engine.

ABS rated -40°C to +80°C, no sunlight, I was using this it's low cost.
Polycarbonate rated -40°C to +120°C, UV is okay
Aliexpress rated nothing, melts if you look at it.

pic is of what the low profile finnbox looked like.

Yes you are right Redwire, the CDI box is located under the seat and is not in a exposed area to the wet. its more likely to just get damp under there.
The height of the box is more important than any other dimension as if its too high it might be subject to the seat pressing down on it or even the seat may not fit anymore. Otherwise there is plenty of room around it. If it was larger than the original it would be fine as long as its not higher.
I've spent hours going through that awful schematic and and following the circuit through against the real PCB. and I can only find one resistor R21 which is directly connected to R25 and R20. There is only physically one single R21 on this PCB which sits mounted vertically just to the right of R25 and below R20 (in tube). The value of R21 on my PCB is 910 ohms. see photo.

[roadrash]

Have you managed to get all you need Redwire? I've almost finished putting the old unit back together and just have a few broken resistors to replace. I am only reassembling it for reference purposes if needed.
Is there any more info you need from me Redwire.

[redwire]

Will this enclosure fit? Bud PN-1323-DG
It's the same size as Finnbox but thicker and people were using Velcro to mount it. I'm not happy with all that but it needs to be waterproof because of the high voltage. If you know of something better, I'm all ears. I have all the part values and circuit.

[roadrash]

Originally Posted by redwire

Will this enclosure fit? Bud PN-1323-DG
It's the same size as Finnbox but thicker and people were using Velcro to mount it. I'm not happy with all that but it needs to be waterproof because of the high voltage. If you know of something better, I'm all ears. I have all the part values and circuit.

Just took a look on my bike and the CDI box sits in a recessed space in the frame, below the seat. Your box would not fit as the space available is not much bigger than the original CDI box which was 134 x 65 x 35.
The maximum size of the recess in the frame you can see in the picture is: 130 x 65 x 35mm.

The maximum size in the tail space behind seat is 180 x 90 x 45mm

[stj]

is something wrong with the original box?
why not just sray conformal coating on the board or paint it with rubber and then use the original box?

[redwire]

The original module had a tight size then because it was potted. Putting 1/4W resistors vertically saved space but is not good for vibration. And then you need to bolt the board down to the can.
Due to the high voltage, many parts are big through-hole.

What about one size smaller, Bud PN-1321-DG or Hammond 1554C? If I use some SMT parts it could fit. But still 11 wires to get out.

[roadrash]

Originally Posted by redwire

The original module had a tight size then because it was potted. Putting 1/4W resistors vertically saved space but is not good for vibration. And then you need to bolt the board down to the can.
Due to the high voltage, many parts are big through-hole.

What about one size smaller, Bud PN-1321-DG or Hammond 1554C? If I use some SMT parts it could fit. But still 11 wires to get out.

I think the Bud PN-1321-DG is the most likely as its only a fraction higher than the original.
The original is still in great shape and there is a plastic sheet that keeps the pcb from shorting on the bottom. I would have to make a good job of sealing it up again but otherwise it would be ok and I could also reuse the original rubber sealing piece around the input and output connections. Original case inside dimensions are (mm):
Length=92mm, width=55mm, 30mm.
Just do what you prefer Redwire I would be more than grateful for anything you can do for me and that would keep this old CX500 going.
Was that value of R21 ok at 910 ohms. I dont know why its differnt to whats on that Schematic. It might be a good idea for me to go through all the resistors and check the values against that schematic.

[roadrash]

Originally Posted by redwire

Will this enclosure fit? Bud PN-1323-DG

I have just checked all resistor values on schematic against the ones on the pcb and here are the results. Some resistors I was unable to find.

resistors used
===============

ON PCB On Schematic
======= ==============

R1 to R12=470k
R13=82Ω
R14(x2)=82Ω
R15=330Ω
R16=27k
R17=22Ω ................................. 1k
R18n cannot find on pcb or schematic
R19=180Ω
R20
R21
R22=470Ω
R23=680Ω
R24=CAL
R25=820Ω cannot find on schematic
R26=470Ω
R27(x2)=CAL

R17 is 22Ω (grey/red/black/gold) on pcb but schematic says it should be 1K
R14 & R27 are duplicated on the schematic but not on the pcb.
except for R17, all values on pcb and schematic are the same.

[stj]

did r17 meter as 22ohms?
because reverse the colours and convert gold into brown to allow for age/heat and you get 1k

[roadrash]

Originally Posted by stj

did r17 meter as 22ohms?
because reverse the colours and convert gold into brown to allow for age/heat and you get 1k

Its definitely brown red black gold but when I tested it it gives a error so it's duff anyway by the look of it.

[stj]

brown red black gold is 12ohms