I am thinking now that the problem may be ripple on the DC power supply. I suspect that the large electrolytic capacitor at the middle bottom edge of the board is the main reservoir capacitor. If it is then measure the voltage between it's pins (Preferbly with the relay energised.) and also see how much ripple there is with an oscilloscope. I would expect the voltage to be about 12 volts.
I also suspect thet the TO220 device next to the trsnsformer is a 5 volt regulator to suupply 5 volts to the microcontroller. I suggest checking for ripple on the 5 volt rail. (I am thinking that ripple on the 5 volts could cause the microcontroller to misbehave and give incorrect timing and other problems.)

Les.

 

I am thinking now that the problem may be ripple on the DC power supply. I suspect that the large electrolytic capacitor at the middle bottom edge of the board is the main reservoir capacitor. If it is then measure the voltage between it's pins (Preferbly with the relay energised.) and also see how much ripple there is with an oscilloscope. I would expect the voltage to be about 12 volts.
I also suspect thet the TO220 device next to the trsnsformer is a 5 volt regulator to suupply 5 volts to the microcontroller. I suggest checking for ripple on the 5 volt rail. (I am thinking that ripple on the 5 volts could cause the microcontroller to misbehave and give incorrect timing and other problems.)

Les.

Yes - PSU electrolytic is the second most likely thing to have failed after this length of time.

 

Thanks @MrAl. I agree that the 30A surges could shorten the life of the relay. But wiring a different relay in the box is what I was also thinking about - it would be simple as there is stacks enough room in there. The reason for not buying a new control board is that it costs around AU$300 which for our volunteer run hall is a bit steep.

@BobTPH , I also though about the sensing circuit. It's not mechanical though. I think it's some sort of proximity reader or metal detector unit. I didn't take a picture of it, but its about 10mm x 5mm in profile and about 10mm deep. Buy each coin I was dropping in registered on the small led light in the box, so I assume that was ok.

One thing I didn't mention, one user said it didn't work well in the morning, but was fine in the afternoon (or vise versa). So maybe temperature affects the error?

@MisterBill2 , there are IC sockets. You're absolutely correct. I should try to carefully pry them out and re-seat them. Moisture over time could have affected them.

One of the hall users just rang me and told me the heater worked perfectly bypassing the coin box. So it is in the box. I think relay replacement is next...

 

OK, I think I'll try replacing the power relay...

Could someone please look at these 2 datasheets and tell me if they are equivalent:

1. Original OMRON relay (LINK) (datasheet)
2. Proposed TE Connectivity (LINK) (datasheet).

I believe these are both 30A, 240VAC, 12VDC (coil?), PCB mount, 4 pin, SPST (?)

 

Thanks @MrAl. I agree that the 30A surges could shorten the life of the relay. But wiring a different relay in the box is what I was also thinking about - it would be simple as there is stacks enough room in there. The reason for not buying a new control board is that it costs around AU$300 which for our volunteer run hall is a bit steep.

@BobTPH , I also though about the sensing circuit. It's not mechanical though. I think it's some sort of proximity reader or metal detector unit. I didn't take a picture of it, but its about 10mm x 5mm in profile and about 10mm deep. Buy each coin I was dropping in registered on the small led light in the box, so I assume that was ok.

One thing I didn't mention, one user said it didn't work well in the morning, but was fine in the afternoon (or vise versa). So maybe temperature affects the error?

@MisterBill2 , there are IC sockets. You're absolutely correct. I should try to carefully pry them out and re-seat them. Moisture over time could have affected them.

One of the hall users just rang me and told me the heater worked perfectly bypassing the coin box. So it is in the box. I think relay replacement is next...

To expand on the IC sockets idea...

If they are single wipe sockets there is more concern for failure. If they are double wipe that's a lot better, but machine pin sockets are much better and should be ok. You can check into this.

I also have to recommend changing out the electrolytic capacitors. They don't usually last long if they are subject to high ripple current. That means the power supply filter caps.

At quick glance, it appears that the TE relays are not specified as well as the original relays. That's a big deal.
That could be why the original relay lasted so long it is clearly spec'd very well covering max switching current as well as average current. If you were to use a TE relay, I would use a much higher rated one than the original.
I did not compare shapes or terminal positions.

Of course you should already know you have to match the coil resistance pretty close.

 

Could someone please look at these 2 datasheets and tell me if they are equivalent:

Close enough I think.

 

Close enough I think.

The specifications are much different. That means I would get a higher rated device if I was going to uses the TE types.

 

The specifications are much different.

Which parameters do you feel are important?

At this point, I would be interested to know what the relay is controlling in the gas heater. 250V at 30A is 7.5 kilowatts, and given it's a gas heater, I can't see what the relay would be switching that comes close to it's max rating.

 

I have a friend who resurrects old pinball machines. Based on his frequent "BUSTing" (Bitching Up a STorm), I would say the symptoms in posts #15 and #23 indicate a problem with the coin detection mechanism. A fraction of a millimeter is all it takes to miss a coin going by.

Also, that relay is very common. Originally designed by Bosch for cars, just about everyone who is anyone has produced it. I've used the T9 series since the 80's. It should be a drop-in replacement. Note that the contact pins a pretty fat, and will need some serious heat to desolder. Be careful not to pull the plating out of the holes. For this and other reasons, I would put more effort into eliminating other possible causes before going after the relay (unless I missed something in the thread).

ak

 

At this point, I would be interested to know what the relay is controlling in the gas heater. 250V at 30A is 7.5 kilowatts, and given it's a gas heater, I can't see what the relay would be switching that comes close to it's max rating.

I doubt that it is. It is a very common, low cost power relay for automotive and industrial control applications. It works very well in applications with unknown and unsuppressed inductive loads, such as the solenoid in a gas control valve. It is way oversized for this particular situation, but the same control box could control a dozen heaters in parallel, fans, water pumps, etc.

There are jillions of timer, remote control, and relay modules on ebay and alliexpress that all use the same 10 A relay. The relay in this coin box is the 1980's equivalent of that.

ak

 

Many gas heaters use an external thermostat to control the gas valve, as do most gas furnaces. Then a blower is controlled by an internal thermostat that senses when the heater is able to deliver heated air. And we still are not certain as to just what the complaint is.
AND, AK is correct in that we do not even know what voltage the relay is switching, nor what current, although I am guessing it is te mains voltage, if the three wires in the photo in post #1 are the only connection to the control board..
Besides that, it seems that there may be another switch that the user needs to switch to start the heater.
One more thing is that looking at the photo in post #1, none of those wires would be used for 30 amps, probably not even 20 amps.

One simple very old diagnostic trick that can reveal a lot is to give the coin control box a slap if the system does not work correctly. If that gets it playing again then the issue is at least partly mechanical.

 

Which parameters do you feel are important?

At this point, I would be interested to know what the relay is controlling in the gas heater. 250V at 30A is 7.5 kilowatts, and given it's a gas heater, I can't see what the relay would be switching that comes close to it's max rating.

Yeah that's true we don't have the entire story most likely.

It was not an issue with the parameters themselves that I was bringing attention too, it was how they were specified. The original relay manufacturer seems to have specified their relays in much more detail.
For example, one spec might be the current rating. They specify that for a wide range of current levels including short term overcurrent. I would think that means they put much more testing into their list of specifications.
I would tend to trust one of their relays more than the other manufacturers relays.

 

The fact is that the better manufacturers ARE quite happy to provide the details that do show that their products are better. Those sellers that pedal assorted low quality products .