A Replacement circuit board

This is a long shot, but just maybe, somebody can help.

I have a rather old digital safe that no longer works digitally, so we have to use the emergency key. I recently decided to investigate and found that the circuit board is faulty - the keypad and everything else is fine. I've tried for days to find a replacement board, but have failed. The faulty component is the eprom.

Can anybody help please?

The following photos show the safe and the circuit board.

The eprom presumably holds the firmware, so you need both a new component and the code?  And there is only one IC on the PCB so it's presumably a processor with embedded flash.  How do you know it's faulty?  Could you peel off the label saying 220101 so we can see the type number?

Edited By John Haine on 03/08/2018 13:53:10

Edited By John Haine on 03/08/2018 13:53:39

Edited By John Haine on 03/08/2018 13:54:14

Came across someone who fitted an Ardunio system instead if this is feasible.

**LINK**

I know you have made investigations, however does applying power directly to the latch solenoid unlock the system? if it doesn't there is your fault.

There is no eprom in the system - the chip will be a processor as has been already mentioned. If that is the fault you will need to replace the chip (quite easy) and then find the code it was programmed with (IMHO unlikely to impossible)

I doubt if pcbs were ever made independently of the safes so your choices are down to someone who has a faulty safe with a good pcb (what can go wrong with the rest of the safe except perhaps leaky batteries?) or buying a good safe and hoping you can swap the board. I note your safe seems quite large, but the 'front panel' seems the same as those on cabin/hotel room sized safes that go for £15 upwards on the auction site. 

Edited By Nick Clarke 3 on 03/08/2018 18:09:28

Yes, the solenoid works fine, as does the keypad. Since the PCB shows no signs of trauma I'm assuming its the eprom.

Here's a photo of the board with the eprom number exposed, but since I have no means of getting and burning the code, I'm really looking for a complete replacement - possibly from a scrapped safe.

If it's an old PCB, I'd try changing the capacitor before condemning it to the bin.

Electrolytics do tend to expire with age.

Bill

I would first check that the power from the battery holder was getting to the PCB. There could be corrosion on the battery holder contacts. ICs are normally very reliable so I think it is more likely the fault is some other component or connection.

Les.

You also have two transistors on there and i would guess one is to switch the solenoid on so check them also , are any of the leds lighting up or changing state when you enter the code ? 

If you have a search on the net for the data sheet for the chip so you can check the pinouts to find the power and ground pin and check to see if it is getting power .

Whats the other side of the board look like ? Have you checked for dodgy solder joints or damaged tracks ? 

The black connector looks deformed , it looks like it is bulging in the middle if it is maybe a crook connection there ?  

If all else fails you could swap that board with an arduino and connect up the keyboard to it , there are plenty of code lock projects on the internet .

Edited By XD 351 on 04/08/2018 00:24:26

I've tried goog;ing the chip, no success, has anyone else found what it is? I'm guessing PIC of some kind, but having a pinout would be a good start

Edited By duncan webster on 04/08/2018 22:22:09

Same here and the closest i got to anything that uses any of the numbers was 0405 which is a hex inverter.

I find it hard to believe that the chip just died , usually it is because something else has gone wrong and killed it .

It could just come down to a crook keypad or a bad connection somewhere

The only other option i see is to try and contact the manufacturer and see if a replacemnt board is available other than that it may be a bin job .

I didn't get anywhere with the PCB number either.

I'd still go with testing the diodes, easy enough with a multimeter.

Change the electrolytic capacitor; they are cheap enough.

Test/replace the three other semiconductors Q2-4

The disk capacitor C4 should be reliable enough.

Do a continuity check on the inductor.
are there any other components on the reverse side of the board?

How was the combination set? A quick Google shows that there are some witlessly stupid circuits around for combination locks, one for example uses just a dual D type flip flop.

**LINK**

They seem to have limited key lengths and the combination is set by hardware links. So we may be assuming this unit is cleverer than it really is!

Gary,

My advice would be to weld in a bracket to accept a proper keyed lock and do away with the electronics/electrics.

These elecronic digital safes are not regarded as particularly safe. I would not store anything really valuable in one.

I have a couple, but only store things of low value that I wish to try to keep meddling fingers away from - not to prevent theft by any low scum.

.

It appears to be very similar to this one: **LINK**

http://www.hilka.co.uk/support/manuals/s-25ea(ii).pdf

I have the S-25E version of that one, and was hoping to assist Gary ... but the pcb is a different layout

... 'though probably functionally similar.

MichaelG.