SEF 551.10 - How to raise the temperature of the unleaded soldering furnace? - Page 1
Forum section: electronics / general

author: bpjl
author_rank: Contributor
timestamp: March 16, 2025, 03:27:36 pm
content: Hi,We continue to struggle with the SEF 551.10 reflow oven. After we managed to start it in october - the topic here ->https://www.eevblog.com/forum/repair/sef-551-10-error-starting-the-reflow-oven/everything promised to be good. But...While soldering with lead paste somehow goes, but we cannot force the stove to raise the temperaturethat he would dissolve the unleaded binder. I even doubted what this bastard shows on screen and passed through it a thermocouple connected to an external meter. The maximum temperature that was obtained is 190°C.Maybe someone used such a stove and could share their knowledge of what we can do wrong?I will add that the device shows nothing, what could suggest that a heater or fan does not work.I have some suspicions related to the configuration file that loads into the furnace with the software. We got it with files from the manufacturer when there was a problem with starting (see link above). But we are not sure if it is a good configuration for this stove,or just a general configuration file.We wrote e-mail to the manufacturer in this matter and we are waiting for answer. But maybe someone has knowledge about this? Configuration file is in the attachment.

author: JURP
author_rank: Contributor
timestamp: March 17, 2025, 06:39:01 am
content: Just some ideas:1) are all the heaters heating?2) at room temperature do all the zones show the same temperature?3) should I temporarily attach an external thermocouple to the internal one and compare their values? I don't believe in the ideal configuration in .ini TempOffset=0

author: SMTech
author_rank: Frequent Contributor
timestamp: March 17, 2025, 09:08:31 am
content: There's a pretty extensive manual I can see online. Maybe you could post a screenshot of the Oven profile you have created (running) for lead free so we can see what you have set and what the oven says it is acheiving.Have you attached a thermocouple and measured the profile on the board?I can't speak for the zone settings you should be using in your specific oven with your product, however with a heated length of 850mm you can determine the speed range it should run at.Lead Free paste typically has a reflow profile of 3 to 4.5 minutes, so the speed should be between 19 and 28CM/min.A ramp to spike profile can be more efficient, but if you have a large heavy board or components like inductors that suck up a lot of heat, a more traditional & slower ramp-soak-spike profile might be the only thing that works. Use your thermocouple to monitor the most critical sensitive of complicated parts of a sample board to dial in the profile make sure you have read both the datasheet for the paste and any component that might have special requirements.

author: bpjl
author_rank: Contributor
timestamp: March 17, 2025, 05:52:39 pm
content: Quote from: JURP on March 17, 2025, 06:39:01 am1) Yes2) Roughly speaking yes3) A very good idea, although it is very difficult to get to internal temperature sensors while working.Quote from: SMTech on March 17, 2025, 09:08:31 amOf course, but only in two days when I am at work.Quote from: SMTech on March 17, 2025, 09:08:31 amThis is another puzzle. It doesn't matter if the thermocouple is connected and moves with the PCB through the stove or it is not at all, the device records exactly the same temperature measurement creating a profile chart.

author: bpjl
author_rank: Contributor
timestamp: March 21, 2025, 05:23:52 pm
content: I decided to start from the beginning and calmly.I wanted to start by re-uploading the owen software with the original, unchanged, globalpams.ini file. This time my attention was caught by the fact that in addition to the file for installing firmware (this file contains globalpams.ini) is a separate globalpams.ini filealso sent by the manufacturer in connection with the previous machine failure. Why didn't I see it before?I compared the contents of both globalpams.ini files and it turned out that there are differences in two parameters:# Coustumer configuration 6 Photo Sensor and Stand by Functionand# DebugI have no idea what impact these parameters on the owen work, ut after replacing the globalpams.ini file and uploading the software, the device began to react to my instructions. Or is it a pure coincidence? I don't know.It is important that now I can set the temperatures, and their measurement has begun to look real and agrees with the indications of external devices.Quote from: SMTech on March 17, 2025, 09:08:31 amCurrently with such a work profile (chart generated by the owen) and a unleaded solder paste:I get such solder joints (sorry for the quality of the photos):It is still to be refined, but with a clear conscience I can already say that it is good

author: bpjl
author_rank: Contributor
timestamp: April 02, 2025, 04:24:07 pm
content: Since the previous entry, everything has been working as it should. We are now refining profiles. Thank you for your help and advice.