Custom Harness Projects

D_Harris

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I'm back to two projects that I had run into a wall with.

As for the first one. I'm working on a custom wiring set-up and it requires that I extend the connection between a Robotron rom PCB and it's main board, because in my set-up the rom PCB must be situated a couple of feet away, and the OEM cable is only about 4 inches long at present.

The part of the ribbon cable that plugs into the main PCB is a 40 pin dual row header like those that fit an IDE hard drive, but the other end that goes to the rom PCB is a different kind of connector. I have no idea what the part number is of this connector or where to get it. I can't even figure out how to disconnect it from the PCB without breaking it. :-(

Secondly, I'm also looking for someone who can make small harnesses with 18 or 20 gauge wires along with a connector that is also compatible with 40 pin dual row(IDE) header at one end.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.
 
I'm back to two projects that I had run into a wall with.

As for the first one. I'm working on a custom wiring set-up and it requires that I extend the connection between a Robotron rom PCB and it's main board, because in my set-up the rom PCB must be situated a couple of feet away, and the OEM cable is only about 4 inches long at present.

The part of the ribbon cable that plugs into the main PCB is a 40 pin dual row header like those that fit an IDE hard drive, but the other end that goes to the rom PCB is a different kind of connector. I have no idea what the part number is of this connector or where to get it. I can't even figure out how to disconnect it from the PCB without breaking it. :-(

Secondly, I'm also looking for someone who can make small harnesses with 18 or 20 gauge wires along with a connector that is also compatible with 40 pin dual row(IDE) header at one end.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.

Hey Darren,

If you just want to extend the connection and have an old IDE cable of the correct length and with a correctly oriented header connection, the easiest way to do this is to very carefully lift the top restraining clip off of the ribbon where it connects into the ROM board [ do not break the clips or go to plan B ], carefully roll the old ribbon cable off of the pin matrix and press the new [longer] cable in with a vice and lots of paper to protect the PCB.

The part you are looking for to connect the cable directly [soldered] to the PCB, is sold by Mouser, I do not have the part number handy [someone wanna chime in here?]. The header cable part is sold by unicorn electronics.

As for your second project, I have not a clue.

Hope this helps,
Saltbreez
 
Hey Darren,

If you just want to extend the connection and have an old IDE cable of the correct length and with a correctly oriented header connection, the easiest way to do this is to very carefully lift the top restraining clip off of the ribbon where it connects into the ROM board [ do not break the clips or go to plan B ], carefully roll the old ribbon cable off of the pin matrix and press the new [longer] cable in with a vice and lots of paper to protect the PCB.
"Restraining clip"? There is nothing to grab. There is just the smooth black connector at the end of the cable and connected to the ROM PCB. It won't come off and I'm apprehensive about breaking it if I attempt to pull it with pliers.

The longest IDE cables I have are 20 inches but not without one or two connectors along this length in addition to the connectors at the ends.
The part you are looking for to connect the cable directly [soldered] to the PCB, is sold by Mouser, I do not have the part number handy [someone wanna chime in here?]. The header cable part is sold by unicorn electronics.
Well, that is what this comes down to. Finding out the part numbers of the connectors for the ends of these IDE cables.

Is it plausible to de-solder the connector from the ROM PCB and solder in an IDE header? (That way a cable with IDE connectors on both ends can be used to connect the ROM PCB to the main PCB).
As for your second project, I have not a clue.

Hope this helps,
Saltbreez

OK, thanks.

Darren Harris
Staten Island, New York.
 
"Restraining clip"? There is nothing to grab. There is just the smooth black connector at the end of the cable and connected to the ROM PCB. It won't come off and I'm apprehensive about breaking it if I attempt to pull it with pliers.

Look again. It is a retaining clip, it just fits very well into the bottom seat which has the pin matrix. There are 2 clips, one on each end. Be careful. You are going to have to lift this retainer clip no matter which path you choose; unsoldering is best done one pin at a time [if that is the path you go down, not recommended]

Saltbreez
 
The longest IDE cables I have are 20 inches but not without one or two connectors along this length in addition to the connectors at the ends.

These old cables had an engineering limit to the length they would support; noise [signal bleed via induction] along the wire set this limit. Even if you can rig this, there is no guarantee it will work.

Finding the right length cable with the correct header one one end is part of the challenge.

Saltbreez
 
These old cables had an engineering limit to the length they would support; noise [signal bleed via induction] along the wire set this limit. Even if you can rig this, there is no guarantee it will work.

Finding the right length cable with the correct header one one end is part of the challenge.

Saltbreez

The unfortunate thing is that such a cable does exist, so a custom harness is the only option.

Now the question is if it is plausible to completely remove the connector from the board and install something more standard between the main and the rom PCBs.

Wouldn't this give me the option of using better cables to improve my chances of getting a better signal transfer?

Thanks.

Darren Harris
Staten Island, New York
 
I don't know how much noise you're going to get if you make a ROM board cable a couple feet long. It carries address and data busses... Wouldn't it be far easier to build a bracket to hold the ROM board close to the other boards, so you don't have to extend a critical signal cable?

-Ian
 
I don't know how much noise you're going to get if you make a ROM board cable a couple feet long. It carries address and data busses... Wouldn't it be far easier to build a bracket to hold the ROM board close to the other boards, so you don't have to extend a critical signal cable?

-Ian

Not really, because the goal is to switch between Joust, Robotron, and StarGate rom boards on a single boardset.

The switch would of course have to occur somewhere in that cable that leads from a rom board to the motherboard, and the way I was going to do it was with a custom connect/disconnect switcher that would be located just inside the coin door at the closest, though the original idea is the have it just under the control panel.

So, a cable coming from the motherboard would run to these three connectors(switcher), which it turn would run to their respective rom boards.

Thanks.

Darren Harris
Staten Island, New York.
 
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you could use devices like this one (2 devices per rom board. )
http://au.mouser.com/ProductDetail/...=sGAEpiMZZMutXGli8Ay4kAD9bgzCqpNd2dMUI6TnezE=

there are probably other options (there maybe a 40 bit device too - i was looking through a catalogue and daw some 60 pin devices similar to these, just cant find my pdf of the catalogue at the moment!)

you could make a switching system that uses these to isolate (or connect) each rom board in turn to the CPU rom board connector.
as most of the 40 pins are used for data (8 bits), addressing (16 bits) and control (approx another 10) you would need to use two to cover all the necessary io signals. they go high impedance during switch on/off, so only need some simple switching/logic to select which rom board to use.
using devices like these you could:
1. make a short custom cpu to rom cable with:
- 1 x female IDC 40 pin connector
- 3 x male IDC 40 pin connector
2. build a small interface board per rom:
- an IDC header at one end (to connect to rom cable)
- 2 x ics on pcb (or this could be hacked together using a pcb and wires)
- an IDC plug at the other end (to plug into the cable with three eader sockets)
- these plug into 1 above
3. a remote switch selector to set the enable/disable pins on the ics to the correct address
- the selector switch cable can be as long as you like, as the ROM board signal cables remain short.

just a thought!
 
you could use devices like this one (2 devices per rom board. )
http://au.mouser.com/ProductDetail/...=sGAEpiMZZMutXGli8Ay4kAD9bgzCqpNd2dMUI6TnezE=

there are probably other options (there maybe a 40 bit device too - i was looking through a catalogue and daw some 60 pin devices similar to these, just cant find my pdf of the catalogue at the moment!)

you could make a switching system that uses these to isolate (or connect) each rom board in turn to the CPU rom board connector.
as most of the 40 pins are used for data (8 bits), addressing (16 bits) and control (approx another 10) you would need to use two to cover all the necessary io signals. they go high impedance during switch on/off, so only need some simple switching/logic to select which rom board to use.
using devices like these you could:
1. make a short custom cpu to rom cable with:
- 1 x female IDC 40 pin connector
- 3 x male IDC 40 pin connector
2. build a small interface board per rom:
- an IDC header at one end (to connect to rom cable)
- 2 x ics on pcb (or this could be hacked together using a pcb and wires)
- an IDC plug at the other end (to plug into the cable with three eader sockets)
- these plug into 1 above
3. a remote switch selector to set the enable/disable pins on the ics to the correct address
- the selector switch cable can be as long as you like, as the ROM board signal cables remain short.

just a thought!

Thanks, but this will be strictly mechanical. (Make and break). The chip idea wouldn't be as simple or reliable.

Darren Harris
Staten Island, New York.
 
I's still appreciate any recommendations for connectors I can solder to the motherboard and rom PCB in place of the originals.(Preferably connectors that can use 18g leads).

(I still have to figure out how to remove the present cable connector from the motherboard. I appears to be cemented in place).

Thanks.

Darren Harris
Staten Island, New York.
 
I's still appreciate any recommendations for connectors I can solder to the motherboard and rom PCB in place of the originals.(Preferably connectors that can use 18g leads).

(I still have to figure out how to remove the present cable connector from the motherboard. I appears to be cemented in place).

Where's the popcorn... this thread is hilarious.
 
Where's the popcorn... this thread is hilarious.

I think Michael got the last of it:

Jackson_popcorn.gif


-Ian
 
I'm pretty sure a mechanical switch between rom boards and main boards would not be allowed in the Twin Galaxies universe. Even if you successfully achieve this project and hit a new world record score, I doubt that TG would accept the score on a 'non-standard' setup.

Just sayin....'
 
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