By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

A Replacement circuit board

All Topics | Latest Posts

Search for:  in Thread Title in  
Gary Wooding03/08/2018 13:27:15
967 forum posts
253 photos

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.

digital safe.jpgdigital safe pcb.jpg

John Haine03/08/2018 13:51:54
4622 forum posts
273 photos

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

Brian Sweeting03/08/2018 15:43:25
453 forum posts
1 photos

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

**LINK**

Nick Clarke 303/08/2018 17:57:24
avatar
1391 forum posts
61 photos

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

Gary Wooding03/08/2018 18:21:25
967 forum posts
253 photos

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.

digital safe pcb2.jpg

peak403/08/2018 22:19:57
avatar
1672 forum posts
175 photos

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

Les Jones 103/08/2018 22:45:37
2255 forum posts
156 photos

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.

I.M. OUTAHERE04/08/2018 00:08:26
1468 forum posts
3 photos

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

duncan webster04/08/2018 22:21:53
3919 forum posts
61 photos

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

I.M. OUTAHERE05/08/2018 00:32:37
1468 forum posts
3 photos

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 .

peak405/08/2018 02:05:36
avatar
1672 forum posts
175 photos
Posted by XD 351 on 05/08/2018 00:32:37:

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?

John Haine05/08/2018 09:05:13
4622 forum posts
273 photos

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!

not done it yet05/08/2018 12:00:36
6719 forum posts
20 photos

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.

Michael Gilligan05/08/2018 14:16:15
avatar
20057 forum posts
1040 photos
Posted by John Haine on 05/08/2018 09:05:13:

How was the combination set?

.

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.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Rapid RC
Dreweatts
cowells
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest