8x24 KSU keeps resetting

[Kagami]

Hey all, new to the forum.

I have an 8x24 non-DS KSU with DR5 software. It was unplugged for long enough that the system was completely reset. Upon booting it up on the bench with no external lines connected and just 1 M7324 on port 1 (ext 21) it appears to boot normally and the phone display shows "Jan 1 12:00 AM" As soon as I press the feature key to go into config the system clicks as if answering a line and freezes. It will then keep clicking and the phone resetting a few times for about 60 seconds before returning to "normal" operation...and the time will have advanced. If I press handsfree or intercom key it will give dial tone and allow to dial a number before of course showing that extension as out. Choosing any line, pressing release, hold, page etc will cause the system to lock up as above. Only digits and intercom/handsfree work. I tried a different, verified working set as well and it still does not work. Also, since my initial power up it has been keeping track of time successfully on the bench.

Anyone have an idea for why this KSU is acting like this? I was hoping to refurbish the whole system as a demonstration unit of how small office telephony used-to-be (and sometimes still is!) done.

Thanks!

 

[LXLS]

Power Supply problems? Caps on the backplane leaking? Potential Software cartridge issue? These things would be where I'd start.

 

[Kagami]

Did further testing this weekend. What I tried:

- Different software (DR5) and memory cartridge
- Draining caps on backplane and memory cartridge (Did reset time, as I'd expect)
- Checked PSU voltages (20, 5, and 10v all good)
- Inspected every electrolytic - all looked good visually and probed with correct capacitance (with some error for being in-circuit)
- Figured out which component is clicking on every reset: DPDT relay K1 which tones out to the Trunk001/emergency telephone leads (makes sense)
- Went ahead and added a POTS line on Trunk001. Ext 21 rang correctly. Answer and talk worked fine. Pressing release/hanging up the handset froze the system and released the line.

I'm at my wits end now with this thing. I suppose my next logical step is to try a third software cartridge, preferably not DR5. Unfortunately I don't have one on hand.

I did wonder if there are separate DS/Non-DS software cartridges. I only have the one it came with and a spare DR5 from a business that came from a DS KSU.

I guess it's possible one of the two UV Erasable EPROMs on the backplane could be corrupt, but I have no idea where I would possibly find a dump of those ROMs!

 

[curlycord]

DS = Disconnect Supervision
It senses the caller has hung up so it releases the trunk.

NON-DS does not work well with voicemail, the lines will hang as it thinks the caller is still in use.
Match DS software with DS Cabinet and vice versa, do not mix them.

"preferably not DR5"
Next best and final one would be DR5.1

However, since you tried both data cartridge and software cartridge then the cabinet would be the issue.
Is there proper ground?

The clicking usually indicates a failing power supply, if it clicks rapidly then it's spent.
Maybe determine if the clicking is a trunk relay or a power relay.
Grab a line then hang up and see if it sounds the same.

Try another cabinet?
Any reason you do not replace with a MICS? does it have expansion modules?

I assume a budget issue with the client?

=----(((((((((()----=

http://www.curlycord.com

Toronto, Canada

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