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Heller 1809EXL TDM repair

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#85053

Heller 1809EXL TDM repair | 23 June, 2020

Hi. Have an older 1809EXL that was purchased new and has sat idle for years with 270 on hours as of today. After days of testing, unable to melt fresh paste from Loctite (SAC305). The root cause after the investigation is due to one of the 2 TDM modules being out of whack. Not sure why but the zones connected to this TDM is reporting to be green (met the set point temp) yet each of the zones linked to this TDM is 50-75 degrees cooler. After swapping the top and bottom side TDM, the problem follows the TDM module. Has anyone experience on what could be wrong? Attempting to reverse engineer the module which is based on the Cirrus 20 bit ADC and with multiple 74HC4051 muxes to sample the assorted K-thermocouples in the machine. Welcome any calibration hints. If we crank the temp setting to 350 C, the true desired temp is met and the solder melts. We see an oven file used in the calibration - is that where we can alter the offsets to bring the readings and actual temps into spec? We have confirmed the true temps using 2 different external meters. Welcome any ideas - including schematics for the TDM by Analogic (PL10-28983). Thanks!

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#85056

Heller 1809EXL TDM repair | 24 June, 2020

there is a oven setup wizard, I think you should be able to adjust probe offsets there. are the probes original? maybe they are replaced with inadequate ones? also, contacts on TDMs are weak, give them a good clean if you havent already. if you get "communication with oven" error its the motherboard, that big transformer seems to bend the motherboard and create microcrack in traces. putting some tension on board should solve it.

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#85062

Heller 1809EXL TDM repair | 24 June, 2020

Thank you so much for your comments. It sounds very logical as the probes are indeed the original along with the rest of the insides of this machine (270 hours of on time). The entire module is offset by 50-75 degrees cooler so suspecting that the personality of this TDM is skewed. Did note an onboard microwire EEprom on the PCB - guessing that is how the microcontroller identifies the TDM and then references the offsets in the software. Will try to locate the tool you mentioned and will report back. Many thanks again.

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#85072

Heller 1809EXL TDM repair | 24 June, 2020

Hi. Could we trouble you for more info on this process? We did rename the .ovw file so we have a backup. Then ran the wizard which is asking many questions we left as defaults. Then on page 6 there are the max temp for each heater. From the user manual, page down on the last page = page 6? Turn on the PROFILE settings (default was OFF) - we did this and saved. Then launched WAKEUP profile again but do not see anything different than before. We continue to have an offset of temp readings to the actual heaters for all related thermocouples for this single TDM box.

Where can we insert the temp offsets?

Thanks again.

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#85073

Heller 1809EXL TDM repair | 24 June, 2020

Heller is great about their support (at least, they always have been in my past lives). Especially if you bought the machine new.

I would suggest giving them a call, and seeing what they can do to help you. They have also turned up in these forums from time to time, as well.

Cheers, ..rob

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#85074

Heller 1809EXL TDM repair | 24 June, 2020

Thanks Rob. They want to sell us a new TDM which does not sound correct as the entire TDM is with an offset. Logic is making us believe that the calibrated data is stored inside the onboard microwire eeprom. Do not know the format of these expected values but will consider to dump the eeprom tomorrow to have a look. The user manual states that the TDM can be shipped back to the factory for calibration. Do not believe that they will replace any SMD devices for this calibration so believe that they will use a known good temp sensor and store the offset inside this onboard eeprom.

Our oven wizard tool does not mention any configuration for temp offsets for these TDM modules.

We know that we can buy the same TDM module (new & original) at 50% of the cost in Asia compared to the offer from USA. Suspecting that this TDM eeprom has been corrupted and/or erased of the stored values as the unit has sat idle.

Plan B is to just live with the fact that measured temp values + offset = true zone temp. For the most part, it will be a one-time profile configuration.

More updates later, once we know. Thanks for your help.

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