Mason alarm

[Dave Mason]

if the earth connection is so delicate, would it not be better to earth the alarm to the main earth

Yes, well to a different earth. There are many "earths" in a car electrics and with large currents circulating all those "earths" are not quite at the same voltage. Choosing the wrong earth won't do any harm but the Mason alarm may not work properly if it's not sharing pretty much the same earth as the temp gauge.

My problem is that I don't have a Bongo so I need help from you Bongo owners so that I can revise the Mason alarm fitting instructions before I recommence supplying them.

There is another place on the back of the speedo that I used to power Haydns alarm. ... ... This goes into a much meatier nut soldered to the PCB, so would seem to be a better option (highlighted in yellow - it appears to be labelled as SP-).

Simon, that very helpful, thank you. Details matter if I'm revising instructions ... please confirm:
(a) that nut is already soldered on by the manufacturer (sounds slightly unusual), you didn't mean you soldered it on,
(b) that nut already has a screw in it, supplied by the manufacturer (would I have to supply the screw?), and
(c) SP/yellow is a 0v/earth connection (you said "used to power Haydns alarm")

Even then I fear SP (Star Point/main earth?) may be too different an earth - unless someone can confirm it's commoned with the temp gauge earth nearby. Also I'd need to supply the alarm cable with longer tails because that SP is so far from the temp gauge. So is anyone in a position to look inside the fuel gauge cover and comment on whether there's anything fragile around the fuel gauge earth pillar?

[Simon Jones]

Answers below

(a) that nut is already soldered on by the manufacturer (sounds slightly unusual), you didn't mean you soldered it on,
A. The speedo module has a proper PCB on the back. There is metal plate on the pointer side of the pcb which passed thru the pcb & is then soldered. This is quite solid.

(b) that nut already has a screw in it, supplied by the manufacturer (would I have to supply the screw?),
A. The screw is already there - its the same as the temp gauge ones, just longer


(c) SP/yellow is a 0v/earth connection (you said "used to power Haydns alarm")
A. Correct - well its the 0v conntection for it. The +12v comes from a different point at the rear of the speedo connections


Even then I fear SP (Star Point/main earth?) may be too different an earth - unless someone can confirm it's commoned with the temp gauge earth nearby. Also I'd need to supply the alarm cable with longer tails because that SP is so far from the temp gauge. So is anyone in a position to look inside the fuel gauge cover and comment on whether there's anything fragile around the fuel gauge earth pillar?
A. I'll whip it out again this evening (got a duff bulb to deal with anyway). I take a photo of the flexible pcb so you can verify it all the same earth. The difference in length is pretty minimal

[Dave Mason]

OK that's clear enough, thanks very much. However I think I can't use "SP" with my existing stock of alarm cables, the tails look too short to span T-U to SP. So I still have a strong preference for using the fuel gauge's earth if that will be reliable and I'd like to wait for someone to take a look. I know it will work electrically, I need to know if it's mechanically risky to remove/replace the screw.

I could do with a good general pic of the area (fuel gauge, temp gauge, and "SP"), please, for when I revise the instructions, the one I have is overexposed - flash reflection I think. Having a cm ruler alongside in the pic would enable me to check the length of tails required.

There's no rush. It will be at least a week before I revise instructions and accept orders. I have to deal with the "squealing" cases first - and I don't want those customers to add broken temp gauges to their troubles.

[trekie]

hi y'all,
i managed to dismantle the gauge, the earth wire did snap but i cant find the end to reattach and the copper wire is so flimsy i dont have a clue as to how to repare it so it looks like i will need a replacement gauge

cheers

alex and jan

[Linusface]

I fitted the Alarm a couple of days ago.

All working as expected

Thanks Dave.
PM sent.

[telemalc]

OK that's clear enough, thanks very much. However I think I can't use "SP" with my existing stock of alarm cables, the tails look too short to span T-U to SP. So I still have a strong preference for using the fuel gauge's earth if that will be reliable and I'd like to wait for someone to take a look. I know it will work electrically, I need to know if it's mechanically risky to remove/replace the screw.

I could do with a good general pic of the area (fuel gauge, temp gauge, and "SP"), please, for when I revise the instructions, the one I have is overexposed - flash reflection I think. Having a cm ruler alongside in the pic would enable me to check the length of tails required.

There's no rush. It will be at least a week before I revise instructions and accept orders. I have to deal with the "squealing" cases first - and I don't want those customers to add broken temp gauges to their troubles.

hope these help
malc

[Simon Jones]

Well done Malc - you've saved me a job! I've got to pull the panel out to replace a bulb, but I've still got to get packed up for the Bash yet, so was going to have to put it off til next week. Were you able to confirm SP- is the same as E? I've got my Haydn alarm connected to SP- for its negative supply & it works fine.

Trekie - if you're coming to the Bash - I'd be happy to try to fix it for you. Otherwise, are there any techy folks in the Liverpool area who could volunteer to help him out?

[trekie]

hi,
galileo is effectively off the road until this problem is resolved and then the overheating problem. but can anyone answer this one? as i have lost the wire going from the coil of the temp gauge to the pin which the E screw screws into, is it possible to pass a copper wire through the loops of the coil and reconnect it to the pin? i was thinking of using a strand of copper wire or fuse wire. would this work even as a temporary repair until i get a replacement gauge?

cheers

alex and jan

[telemalc]

hi,
galileo is effectively off the road until this problem is resolved and then the overheating problem. but can anyone answer this one? as i have lost the wire going from the coil of the temp gauge to the pin which the E screw screws into, is it possible to pass a copper wire through the loops of the coil and reconnect it to the pin? i was thinking of using a strand of copper wire or fuse wire. would this work even as a temporary repair until i get a replacement gauge?

cheers

alex and jan

hi, i had exactly the same problem, it took me about an hour, working with a small screwdriver, to manage to ply the broken end out, i nearly gave up. a magnifying glass will help the broken bit must be there somewhere. if you find it scrape the coating off the wire and solder a one strand of wire from any bit of electrical cable and then connect to the post.
its an awful design and a lot of patience will be required. hope you get it fixed soon, malc

[trekie]

hi malc,
no the wire is completely gone, i did try the soldering but did more damage to the plastic so i want to avoid a hot repair.

cheers

alex

[Dave Mason]

Damage to Bongo gauge when you remove/replace screws to fit Mason alarm

The situation on the temp gauge terminals seems to be that it is only the Earth screw that poses a risk. The nearest other Earth connection is to the Fuel gauge but that has the same arrangement so potentially suffers from the same weakness - the risk that the internal pillar will turn and break the fine wire attached to it internally. Thanks to telemalc for both those points of information.

So it looks as if the solution will be to use the Earth point marked "SP" as shown below (thanks to Simon Jones for spotting the useful earth point and to telemalc for the picture, retouched by me).

To use this the cable will have to be altered so the "tails" are longer, about 80mm I think.

Now I need someone to verify this connection arrangement actually works before I can incorporate it in the fitting instructions for new customers. Any offers? Either someone who already has one or someone who wants to buy one?

[petebee]

fitted mine today thankfully all went well and the temperature gauge is now sensitive.Just finished reading all the threads about breakage of the small earthwire think that would be too tricky a repair for me.I now have this plus Haydns low coolant alarm and a digital temperature readout from the cylinder head.Towing a caravan to Glastonbury must remember to keep one eye on the road!

[Veg_Ian]

Now I need someone to verify this connection arrangement actually works before I can incorporate it in the fitting instructions for new customers. Any offers? Either someone who already has one or someone who wants to buy one?

As most people will be at the Bongo Bash this weekend, I'll have a go for you Dave. I guess I owe you one for the bum information I gave you last year

I'm rather busy at the mo so it will be Saturday before I can get around to it. I'll strip back the cable and let you know how much longer you need to make the earth wire "tail".

Ian

[Dave Mason]

Hi, Veg_Ian. No, I sometimes think your "bum info" was spot on. How did I get into this?

Tks for the offer. No rush on my part. My suggested 80mm was from where the tails part to where the centre of the screw will go. But actually proving it works properly earthed to "SP" is the more important. Until that's done, and I've then got a stock of suitable cables, I won't offer any more for sale unless someone who wants to buy one is prepared to be the tester. I don't think there's any risk of damage trying "SP", it's just that I can't publish fitting instructions that no-one's ever used!

To avoid risk of damaging the temp gauge earth I would not remove the screw, Ian, cut the wire off near the terminal and splice on an extension to reach SP.

Some bad/good news just in from a customer whose ID I'll protect!...

Hello, I bought a Mason alarm from you last September/October time, and also overtightened the screw, and broke the gauge. Luckily I had bought a pod from a 626 to fit the mph clock, so just robbed the gauge from that. I put it down to my own stupidity/bear like strength, and slapped myself on the hand!

Maybe I should have reported it then, but thought it was a one off ...

By the way, gauge has been on for something like 9 months now and I feel a lot happier having a moving temperature gauge, and have had no further problems. So thank you.

So the bad news is that there has been at least one other (and possibly more) previously-unreported temp gauge failures on overtightening the screw in the temp gauge earth terminal. However I was uneasy about the apparently sudden outbreak of failures. The real good news is that the 626 pod is an alternative source of a replacement temp gauge - but you all knew that.

[Veg_Ian]

Hi Dave, you are very gracious in your reply as ever.

I have to say that in general I find the Mazda build of components to be lacking compared to Toyota, to which you and I are more accustomed. It's as if Mazda engineer components to be 'just adequate' for the job and are not as robust as those from their Japanese competitors. It's not surprising therefore that some people have had trouble with modifying their gauges. Maybe I and others were just lucky or maybe over cautious when fitting ours. Obviously from your position you have to mitigate the risk of someone damaging their gauge when performing what should be a routine task of undoing a screw. Just telling them to be careful is too subjective.

I'll get the information to you asap.

Ian