[Oldmanandhistoy]

You really need to get the schematic or hook-up when you buy this kind of stuff, otherwise you have to spend time 'reverse engineering' it.
Al.

Can’t agree more Al but it was very cheap and an impulse buy. I do have a schematic on paper but it is all Greek to me. I have attached pictures; will these help?

John

[Oldmanandhistoy]

You really need to get the schematic or hook-up when you buy this kind of stuff, otherwise you have to spend time 'reverse engineering' it.
Al.

I really wish there was a way to repay you for all the help you have given me. Just out of interest do you moderators get paid per post or any physical reward for doing it? If not then you are indeed one in a million.

Regards,

John

[Al_The_Man]

The input pins on 10 pin connector on the right have to be pulled low, to the PC/PS common to switch them on.
They use triac opto's to switch the 240vac relays and the contacts on the left switch your loads, as desired.
You may need a buffer between the printer port TTL outputs and the 10 pin inputs to drive them sufficiently, I could not make out the DC supply voltage and opto input resistor values.
Al.

Just out of interest do you moderators get paid per post or any physical reward for doing it?

Yes, another 5k posts and I can retire

[Oldmanandhistoy]

DC supply voltage; the transformer is rated 6V 1.2VA and opto input resistor values are 47R I think (blurred).

Should I just go with the original bob and hope for the best at least until I can import a better one?

John

[Oldmanandhistoy]

Just one last thing; how easy is it going to be for me to find a plug for the 10pin connector? Does it have a name?

John

[Al_The_Man]

Can't really see what type J4 is?
I would think the original BOB would give you the least grief.
And a bit more flexible.
Al.

[candle]

Oldmanandhistory: uhm.. this is connector used in philips and grundig crt tv (acient i must say), older pdp displays, nokia crt monitors... not that easy to find
got similiar to those as molex part mx-51021-1000 (enclosure)
mx-50079-8100 (terminals)
but i think you would have to replace socket as well (mx-53047-1010)
but if i remember correctly - pads are in zig-zag pattern, and molex uses straight line
if it is so, then replace with AMP Micro-MaTch connectors
should have same raster

Al has right - BOB board is more flexible, and designed to the job (poorly, but designed )
i would marry them, or build my own from scratch, but this is not the path for You to follow i pressume

[Oldmanandhistoy]

Al,
Thanks for all your help; I will be using the original bob for now until I find a better alternative. Would still like to know if one of those relays fails with 240Vac going through it, will it just destroy the PC or possibly the PC and me?

Candle,
Thanks again for your help; unfortunately I am a dead loss with electronics so will just buy a new bob.

I know I am pushing my luck with this thread but I just need to know one more thing. Will I be creating a ground loop if I use the same mains supply for the stepper motor drives PSU and the PSU for the BOB? If the BOB required 5Vdc I could have used the PC PSU and then I would definitely been ok but this 6V supply has got me confused to where the mains supply needs to come from. All the mains supplies for the machine will be coming through one cable for PC, PSU for drives and spindle.

EDIT: Is the dc isolated from the ac in a switch mode PSU?


John

[Al_The_Man]

Like I mentioned there is only a very remote possibility that the isolation might fail, but in my opinion, it is tempting fate controlling that kind of load ( spindle motor).
To put it in perspective, I could not see a machine set up for industrial use, use a relay like that for other than low current, predictable loads.
I imagine there are many out there that are going to say they have had no problems, but for a couple of bucks to spring for a heavy relay is worth it, and just use the on board one for intermediate function.
Switching power supplies do not usually come with the common to ground, in the case of a PC it often happens that this usually occures, because the incoming service ground is connected to the PC case via the PS, and the MB ground plane is connected to the case by at least one securing screw in most cases, this grounds the DC side.
Remember that service ground is actually one side of the AC supply, which is made common at the service entry point.
If you or anything comes in contact with this one AC line, no effect is felt because it is common to earth ground (neutral), Only when contact is made to the Hot side is the effect FELT.
If you connect supply commons and any equipment ground connection to this main ground conductor, every common has, or shouldhave equal zero potential.
It helps if a common point is picked in the enclosure where all grounds are connected to, including sheilds etc.
You create a ground loop if you ground a part of the system in different places, this is why it pays to set up one point for all grounds, including the service ground, also grounds should not be used as a conductor or termination point for loads etc.
It does get confusing sometimes.
One main supply source should be OK.
BTW although the AC neutral is common to Earth at the main panel, do not ground it anywhere else at all.
Al.

[skiddaw]

You might try grounding the control inputs or loading them with 1kohm to ground.

Unlike a 7404 the 7414 is a hysterisis device. A short noise spike into a 7404 might be passed as such but a 7414 will latch it until the lower threshold is detected. The 7414 is still the correct device to use but inputs need to be driven i.e. GND or 5V. If you are not using all of the relays then make sure unused control lines are loaded one way or another.

There was once a serial output port being used to drive a printer where the input was used for messaging. In one installation the serial cable contained both serial lines but only the printer line was required and the input line was left open circuit. Unfortunately the printer output was 'picked up' by the input line as noise. If you sent the right sequence of print characters they could look like a receive message .... which was then printed ...

[candle]

whereever you have transformer you have galvanic isolation from mains
no worries here
what is it you want really accomplish? maybe some drawings of your setup
i think you have too much of info already, and it needs to be sorted before you use any of this

Al, don't know for Canada, but in Poland, or UK we have line (L) neutral (N) and earth (PE), and earth may or may be not on neutral potential - depends on istalation used in given building - in my place they are the same - connected together, but in printshop i sometimes work for shorting them results in diffrential fuse poping out
apart from that its 100% true what you wrote

[Al_The_Man]

Al, don't know for Canada, but in Poland, or UK we have line (L) neutral (N) and earth (PE), and earth may or may be not on neutral potential -

Unless thing have changed since I was involved in the Electrical Business in the UK, For Every (Domestic) installation an Earth Ground was mandatory, and the Neutral was connected at the point of grounding only, this could be the star point of the distribution transformer.
The quality of the ground had to be confirmed by ground resistance measurement in order to conform.
Industrial installation could differ depending on the supply transformer configuration (delta etc), but in practically all installations I can remember, where there was a 1 phase supply set up, there was a neutral/ground installed.
As I say Things may have changed.
Al.

[candle]

Al, things may not have changed at all - i've never been in UK, but friends that have told me they could not insert anything they own into wall socket, not just because plug differs (that is not a problem for people with polish mentality ;D) but because there are locking mechanism preventing that if plug has no PE terminal
in Poland - PE is an option, and usually when you live in a block of flats or even a hause you don't have 3 wire instalation, just two, and if its flat - all you might do about it is to go with zero type instalation with PE and N connected - better than nothing