hp 3245a FATAL TRAP # (SOLVED Bent ribbon cable socket pin) - Page 1
Forum section: electronics / repair

author: Cyclotron
author_rank: Unknown
timestamp: May 31, 2025, 08:53:25 pm
content: I have a hp 3245a that I am attempting to replace the DALLAS memory with FRAM. I put in the DIP28 sockets and initially put in the FRAM and it said bad CMOS and "FATAL TRAP #" So I swapped the DALLAS modules back in. The BAD CMOS went away but I still get "FATAL TRAP#" after boot up.I'm searching for that error but can't find it. I am about to remove the DIP 28 socks and inspect the board as that's all I did. Anyone with ideas?

author: Cyclotron
author_rank: Unknown
timestamp: May 31, 2025, 10:39:41 pm
content: Alright, I dug out the service manual. First steps is to determine the stage that the failure happens.I hear the BEEP, the RAM test, and then it starts to show the outputs and gives Fatal Trap#I have unplugged the ribbon from the processing board to the backplane and it will give me the error empty frame.That's where I am now. Now I will try to get through doing a full test of the ribbon cable.

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 12:05:45 am
content: Ok, FATAL TRAP solved. The ribbon cable connector that connects to the DIP-28 socket was the problem there. One of the pins got behind the spring instead of in front of it.Now it boots and gives me a 92:BUS error. I can clear that and run a test and it gives me 226:SOUR error.So I'm off to look those up and figure out what I've done to my precious.Cheers

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 12:31:46 am
content: Hmm, it seems the little green fuse on the primary output board for the 15v rail is gone open. Maybe I shorted something while frustratedly looking for where messed up.Typical of me to get solve one thing and make another problem. I've tested to ground and see no issues so I'll order some fuses and get see if that sorts it.Anyone know if it is worth while to do the LTZ upgrade on the voltage reference?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: June 01, 2025, 01:42:05 pm
content: Good Morning Cyclotron, I would recommend you check the current draw of the circuit before replacing the fuse, to see if the size is appropriate.

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 02:07:58 pm
content: Quote from: BILLPOD on June 01, 2025, 01:42:05 pmTrue, I'll wire it up and test the current draw on that path before replacing the fuse. I had the boards lose while sorting the FATAL TRAP, and I suspect I may have shorted the 15V rail inadvertently, as the unit did work properly before my attempt at replacing the DALLAS modules.But who knows, it's a good practice and I'll give it a go.

author: Cyclotron
author_rank: Unknown
timestamp: June 01, 2025, 05:16:01 pm
content: Ok, I setup a test rig to emulate the fuse with another of the same characteristics and ran a current draw. Everything came back ok and the unit has no errors now. I also programmed the FRAM replacements for the DALLAS chips. For some reason I failed to do that the first time I worked on the replacements which was the reason for the initial BAD CMOS error.I spend so much of my time out on the road traveling that when I get home to my hobbies I feel this sense of urgency to get some items done and then that turns into mistakes.I continually coach myself on this but I don't seem to make progress as I keep repeating the same mistakes of "just get it done while you still have some time". None of this is urgent as its a hobby but my work ethic that I use over my career kicks in and get the job done, make progress!Slow down to go fast... It's all set not besides waiting for the replacement fuse to come in. I will now get it setup in its home and run some tests/validations over a few days. I'm happy to scratch this itch of having a 3245A in my lab. One day, I'll get the 8.5 DMM to sit with it.Thank you to this invaluable community for your time, expertise, and encouragement.