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Acc24E3 Amp Enable Relay


JeffLowe
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Three times in the past few weeks we have had failures of the Amp Enable on the Acc24E3 cards at three different customer sites. These are operating Glentek and Trust drives, both at TTL levels with internal 10k pullups to 5V. These machines have been functioning normally for periods up to two years. Are these physical relays, and if so, what is the MTBF/MTTF?
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Three times in the past few weeks we have had failures of the Amp Enable on the Acc24E3 cards at three different customer sites. These are operating Glentek and Trust drives, both at TTL levels with internal 10k pullups to 5V. These machines have been functioning normally for periods up to two years. Are these physical relays, and if so, what is the MTBF/MTTF?

 

We have seen similar failures on Acc-24E3 boards: on the amplifier mezzanine card, the 'Clare LBA716 Dual Single-Pole OptoMOS® Relays Normally Open & Normally Closed' relays have failed. Most of the systems have been running for years without problems.

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These are solid state relays. You should be able to download the QC specs from the manufacturer. These have shown to be very reliable. Please contact support@deltatau.com with the card s/n to investigate this issue.

 

On the one card here I have here I found a dry joint on one of the legs of the gull wing package. A parting line was clearly visible under the Mantis. Probing the pin easily lifted it away from the pad. Possible causes clogged stencil, insufficient paste since this is near the edge of the board, or un-level pins on the component.

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  • 1 month later...

Three times in the past few weeks we have had failures of the Amp Enable on the Acc24E3 cards at three different customer sites. These are operating Glentek and Trust drives, both at TTL levels with internal 10k pullups to 5V. These machines have been functioning normally for periods up to two years. Are these physical relays, and if so, what is the MTBF/MTTF?

 

We have seen similar failures on Acc-24E3 boards: on the amplifier mezzanine card, the 'Clare LBA716 Dual Single-Pole OptoMOS® Relays Normally Open & Normally Closed' relays have failed. Most of the systems have been running for years without problems.

 

J: How many boards have you seen fail? We are on 5 and counting. This failure mode has become very visible to a major customer (18 machines, and more pending) so I really need to find some answers. My contacting the chip vendor for reliability data on the board is just not appropriate.

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Please send pictures of any boards that appear to have manufacturing issues to support@deltatau.com.

 

The one board with a visible crack in the solder joint was repaired and placed into production. I did not get a picture, nor was the serial number recorded. The remaining four boards are at Axis now being evaluated. They are all 1-2 years old and have been functioning normally up to the point of failure.

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  • 4 months later...

In case anyone is still following this thread, The root cause of the amp enable relay failure has been determined. The gate driving the optocoupler was undersized for the current required. An ECN is in place to change this gate to one with a higher drive capacity and the current limiting resistor on the optocoupler was changed as well.

 

Hats off to engineering for digging in this deep.

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  • 3 years later...

This issue is again rearing its ugly head. our service department is reporting perhaps one to two failures in the field per week. These get returned to Axis New England for testing whereupon they return them to us as no problem found. The issue is thermal in nature where turning off for some time will restore normal function. Likewise, hitting the area of the board with canned air will also return functionality. The fault is more common with boards equipped with the ACI card. For reference look at either ECO 4042 or 5839.

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  • 3 months later...

We continue to have amp enable failures, even with the ECO in place. It appears to be thermal in that after leaving the rack off over night it will often work again. This has been discussed with engineering and our understanding this is not the SSR that is failing, but rather the driver circuit supplying the LED in the SSR. Has there been any effort to replacing the driver with something more robust?

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