GF-12 reflow oven - Page 1
Forum section: electronics / repair

author: IconicPCB
author_rank: Super Contributor
timestamp: January 24, 2019, 10:28:18 pm
content: I have one of the old APS GF-12 reflow ovens.Bought it second hand out of USA.To my chagrin i discovered the manufacturer wanted to charge me over a thousand dollars in the form of support ticket when i asked for the "secret" code to run the setup/tune part of software in the oven controller.It didnt happen , i stumbled on the right combination of keys.Machine is running however there is a small niggly problem. The conveyor speed is unstable. I have stripped the conveyor, lubricated motor gerbox combination but still when observing the conveyor the motion is a bit jerky. conveyor will momentarily come to a halt and restart. On average however the conveyor speed is correct.The motion is obtained from a split winding capacitor run AC motor whose speed is monitored by a tacho ( feedback) and speed adjusted by a triac controller.A little bit knuckle headed but....OK the motor drives a 190:1 gearbox whihc then uses a timing belt through a further pulley reduction ratio to drive the conveyor.Since the motor was designed to run on 60 Hz supply I am wondering whether the observed behavior is due to local 50Hz supply .I was wondering whether I needed to Increase the run capacitor value in order to increase the current through the second winding due to change in supply frequency?Presently the capacitor is 5uF/250V.

author: Armadillo
author_rank: Super Contributor
timestamp: January 24, 2019, 10:50:00 pm
content: Stumbled on the Right keys? hahahahah LOLI hope to do that sometimes;What's the trick to stumble, like to learn from you.Regarding the motor, could be mechanical.I would separation the drive and the tacho from the troubleshooting by powering the motor directly thru a variac.With this, I can determine if its mechanical or not.OK please send the stumble method over. thanks.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 24, 2019, 11:25:05 pm
content: Good idea,I was just recently gifted a variac and isolation transformer....On the question of stumbling... its a bit like tango...got to know the moves... it is not a contortionist act.The keyboard has two groups of keys F1, F2, F3and four arrows and Enter keyI knew the code for setup function in my caseF2 . left arrow, up arrow , down arrowA two handed two fingered salute.So in similar vein the Tune code turned out to be F1 left arrow down arrow right arrow... just like a steamy tango

author: IconicPCB
author_rank: Super Contributor
timestamp: January 26, 2019, 08:20:40 pm
content: Meanwhike....Back to the original question change in capapcitor versus change in frequency?

author: Armadillo
author_rank: Super Contributor
timestamp: January 26, 2019, 08:25:53 pm
content: Only Change in the Phase of push like shift to Gear One, frequency is the Same, no change.Surely you are going to look at the Tacho or speed feedback, give it a good cleaning or function test it.

author: IconicPCB
author_rank: Super Contributor
timestamp: January 27, 2019, 02:25:19 am
content: Frankly,I am a bit on the lazy side.... Decoupling the tcho means disassembling oven down to the conveyor mesh in order to access the motor tacho mechanism.I thin i may just trial an additional microfarad or two in parallel with existing five microfarads.A five minute job.tomorrow.. the sun is beating down its midday.. and the aircon is quietly purring in the background... think I might go back to post lunch snooze..

author: PKTKS
author_rank: Super Contributor
timestamp: January 27, 2019, 12:41:27 pm
content: 1000 bucks for what ? ...DUMP this **** (ditch on near potty) with 1000 buck you got far better gear from CHINA.and cheaper... and w/Open Source code available .. .and forum support..1000 buck for what ?

author: IconicPCB
author_rank: Super Contributor
timestamp: February 01, 2019, 01:14:23 am
content: Erratic conveyor issue resolvedThe three thermocouples are packaged into individual metal tubes ( 1/8" diameter ) and then located in a screw down gland inside the heat chambers.Over a period of time the external glass fiber sheath becomes contaminated with consumed flux smoke and soot.The outcome is an unwanted path from thermocouple to machine frame. The path causes the machine to to fail with a thermocouple alarm every now and then despite the fact that the junction is OK and the leakage current also contributes to erratic behavior of conveyor speed control.I have replaced thermocouples and the conveyor speed has stabilised, there are no longer the usual conveyor hickups.In the hope someone finds this useful in he millennia to come.

author: KG7AMV
author_rank: Frequent Contributor
timestamp: November 15, 2020, 01:20:06 pm
content: I got one of these GF-12's for the shop..Detailed Photos of the Guts are On My Blog if anyone is Interested.http://www.stevenrhine.com/?p=14183

author: IconicPCB
author_rank: Super Contributor
timestamp: November 16, 2020, 01:51:45 am
content: Your machine, while externally similar to mine is significantly changed.The controller is changed. It is based on a 6800 microprocessor where as in my machine it is based on a Zilog micro.I also note the location of conveyor motor is from the front side of the machine whereas in my machine it is accessible from the rear side of the machine.There are two cooling fans, I had to install the second fan after experiencing some overheating issues.I also experienced problems with the thermocouples which enter the tunnel from the top side unlike Yours which has thermocouples on the side of the chamber.When the thermocouples through use become contaminated with soot and garbage they become leaky which in my machine produces an interaction between thermocouple circuit and conveyor speed control circuit.The other difference is the content of the display when operating under different options.Come to think of it looks like the side entry wiring is power to the heaters not thermocouples. In my machine power to the heating elements is applied from the rear of the tunnel.I have also had to take care of the two brass rails running the length of the tunnel providing support for the edges of the conveyor. They were a bit bumpy.. worn out.Battery gets worn out... keep the machine plugged in every now and then so that the battery does not keel over.As far as the key codes are concerned there is no universal set of codes that operate all machines.Your machine may have a subset of all possibilities and your codes may not work with other machines.