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Electronics => Repair => Topic started by: IconicPCB on January 24, 2019, 10:28:18 pm

Title: GF-12 reflow oven
Post by: IconicPCB on January 24, 2019, 10:28:18 pm
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.
Title: Re: GF-12 reflow oven
Post by: Armadillo on January 24, 2019, 10:50:00 pm
Stumbled on the Right keys? hahahahah LOL
I 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.
Title: Re: GF-12 reflow oven
Post by: IconicPCB on January 24, 2019, 11:25:05 pm
Good idea,

I was just recently gifted a variac and isolation transformer....

On the question of stumbling... its a bit like to know the moves... it is not a contortionist act.
The keyboard has two groups of keys F1, F2, F3

and four arrows and Enter key

I knew the code for setup function  in my case
F2 . left arrow, up arrow , down arrow

A 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
Title: Re: GF-12 reflow oven
Post by: IconicPCB on January 26, 2019, 08:20:40 pm

Back to the original question change in capapcitor versus change in frequency?
Title: Re: GF-12 reflow oven
Post by: Armadillo on January 26, 2019, 08:25:53 pm
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.
Title: Re: GF-12 reflow oven
Post by: IconicPCB on January 27, 2019, 02:25:19 am

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..

Title: Re: GF-12 reflow oven
Post by: PKTKS on January 27, 2019, 12:41:27 pm

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 ?

Title: Re: GF-12 reflow oven - resolved
Post by: IconicPCB on February 01, 2019, 01:14:23 am
Erratic conveyor issue resolved

The 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.