What's new
What's new

1995 Bridgeport EZ path 1 bmdc problem

Jefenhauser

Plastic
Joined
Apr 17, 2018
I just purchased a 1995 EZ path 1 got it all wired up and got pretty much nothing because the computer battery died and leaked. I got a new motherboard and back plane and she came to life except the no bmdc desktop error. I cannot find the b3t.exe file anywhere to down load to test . I also checked the power supply voltage which is me and it is good. Am I doomed to another $1000+ board? Any help would be appreciated.
 
No BMDC desktop doesnt necessarily mean your BMDC is bad. When you say that your power supply voltage is "good" what exact voltages are you getting? You are looking for about 5.0-5.2VDC and 12.0-12.3ish.

There should be a green flashing light on the BMDC. Does it flash on every other second or does it flash once every three seconds?

Jon
H&W Machine Repair
 
I did not see a green LED light up at all. I believe that LED is close to the top of the board in the center correct? I checked the Power Supply , which is brand new and the voltage was 5.0 and 12.0.
 
Jon likely has more experience and knowledge than I here, but I'd make sure you are getting voltage through the ISA bus and it is getting to the card. In short, verify that your motherboard or backplane is actually good.
 
I have read even new back planes can be bad. I have swapped the mother board and the BMDC board in to various slots and the Mother board works every time. How do I Check that ISA slot voltage?
 
I have read even new back planes can be bad. I have swapped the mother board and the BMDC board in to various slots and the Mother board works every time. How do I Check that ISA slot voltage?

I don’t recall which are which off the top of my head. It’s been more than 24 hours. You’ll have to google the ISA bus pin assignments and prove the pins with a DMM. Could be as simple as pin not making good contact with the card when it’s inserted. Could as well be a dirty/corroded trace. Use the old pencil eraser trick to clean those as well.
 
Well last night I cleaned to BMDC board contacts with an eraser, made sure all chips were seated on the board and inserted the board into the back plane several times to insure a good contact with no improvement on the No BMDC Desktop error. I also checked the PC health screen and it said the 5 volt was measuring 5.12 volts which is weird because with the multimeter it checks 5.0 volts almost exact. I know the 5 volt is sensitive and I was told T have up to 5.2 volt so I am at a loss why this isn't working. I will call about a new board shortly.
 
Well last night I cleaned to BMDC board contacts with an eraser, made sure all chips were seated on the board and inserted the board into the back plane several times to insure a good contact with no improvement on the No BMDC Desktop error. I also checked the PC health screen and it said the 5 volt was measuring 5.12 volts which is weird because with the multimeter it checks 5.0 volts almost exact. I know the 5 volt is sensitive and I was told T have up to 5.2 volt so I am at a loss why this isn't working. I will call about a new board shortly.

Contact member Bug Robotics. He repaired ours. Was SIGNIFICANTLY less than the result of your phone call.
 
512VDC is perfectly fine for your power supply. Typically I see 5vdc power near there than closer to 5.0. The 12VDC signal is what controls the movement, which is done through the BMDC. The light could also be not on the edge of the board, but be on the actual face of the board.

However, that also has me worried. For some reason, the BMDC was designed to actually not work if the lights are out broken or the solder to the lights is jacked up. If you are not getting any lights, this could definitely be the issue for it.

On your backplane, did you only connect power at P8 and P9 connectors? Thats the 2 connectors with like 6 or 8 wires. DO NOT hook up both P8/P9 AND the 4 pin connector at the bottom of the backplane (if you got the SBC upgrade kit from EMI, that is. Cant tell you about other motherboards/backplanes.)

Jon
H&W Machine Repair
 
The LED on the face of the board has never come on from what I have noticed. The 2 Red LEDs on the edge come on during boot up but turn off after the BMDC test. I only connected the P8 and P9 connectors so n worries there. The boards came from BPT parts and look to be standard 386 back plane and mother board. BPT didn't have the exact replacement board and EMI never returned my call yesterday so I sent the board to Global Electronics Services for repair since they are local to me. If it is something as simple as a bad LED stopping the board from working I would be thankful for just getting it repaired as compared to replacing the board. Thank you for your help on this!
 
Ok, I got the BMDC board back which was less than 24hrs and I'm still in the same situation "No BMDC Desktop". Voltages are all good still and I have swapped around to all the ISA slots no improvement. I can see were they fixed some solder joints and swapped out some components and everything looks to be in order. I am going to take the board back in tomorrow and have them go over it again and for them to check the LEDs especialy the one on the face of the board that has nevver lit up. I wish I had a trouble shooting manual or something. I really need a win....
 
You’d need to verify with Bug Robotics, but I seem to recall that one of my 5v voltage regulators needed replacing. An opto too, I think ... I suck at that stuff. Which is why I go to him.
 
Stupid question... your ribbon cable that goes on the BMDC. Not the one on the end, but the one on the side, it has a red wire on one end. Can you verify that the red wire goes to the pin 1 side?

Sounds to me like you got a bad BMDC. If you wanted to ship it here, I can toss it in my EZ Path and see if it boots up for ya.

I wish they had a troubleshooting manual for it. But thats what PM is for, right?

Do you have any other local shops that have an EZ Path or an EZ Trak that would let you put your BMDC into their machine and boot it up?

Jon
H&W Machine Repair
 
Jon,
I dropped the board back off at Global with your suggestions and my concerns. I may take you up on your offer when I get the board back because I don't know of any one around me that would have one. At work we are mainly a swiss lathe and horizontal mill shop. The department I'm over has Haas CNC and Hardinge manual lathes I did find a picture that hopefully attached showing the red wire on the red cable. This picture is of the BMDC board area before the before the new mother board and back plane.IMG_6962.jpg
 








 
Back
Top