GW Instek SFG-2007 - Transformer Identification - Page 1
Forum section: electronics / general

author: ElectroTech
author_rank: Newbie
timestamp: May 06, 2012, 09:29:40 pm
content: I'm working on a GW Instek SFG-2007 function generator which needs a replacement power transformer. Unfortunately the output voltage is unknown as it was non-functional when I got it. Hopefully someone on this forum can point me in the right direction.Kibi recently posted a teardown of a GW Instek SFG-2110 which uses the exact same transformer...https://www.eevblog.com/forum/product-reviews-photos-and-discussion/teardown-gw-instek-sfg-2110-function-generator/msg103427/#msg103427Clearly, the part number is "3000-FG031001" but internet searches come up blank. Other writing on the transformer is "HP-05719001C" and "HP 57 19 1V" in case that helps. I should post pictures, but other distinguishing features include 6 pins on the primary side and 5 pins on the secondary. The primary pins are 1.2mm in diameter and are spaced 7mm apart. The secondary pins are also 1.2mm in diameter but are spaced 5.5mm apart. The distance between the primary and secondary pins is about 31.5mm, with a slight offset between them.The transformer is designed to handle either 110V or 220V on the input. The secondary appears to have two coils plus a center tap. Because one of the outputs feeds a LM7918 and LM7818 regulator pair, I'd estimate that section to be ~30VAC.Any suggestions are welcome.

author: kripton2035
author_rank: Super Contributor
timestamp: May 07, 2012, 06:42:28 am
content: what makes you think the transformer is deadit is very rareanyway I got one recently, a battery charger to fixmeasure ohms between the primary gives infinite... open loop.you must know that there are fuses in the primary of recent transformers...I teared down the transformer, unwind some wires, and I founs a little fuse in itreplaced the fuse, rewinded, and everything is ok now...In my case, the transformer was also unknown by internet, special windings.good luck.

author: ElectroTech
author_rank: Newbie
timestamp: May 07, 2012, 12:35:15 pm
content: Thanks for your response. Transformers sometimes do bad but usually not on their own. When I received the machine and opened it up the first thing I noticed was the missing fuses. The second thing was the funky smell of burnt plastic.In this case it looks like it took a hit of lightning or was otherwise improperly connected it to some other high voltage because the primary windings are literally vaporized at their connection posts. There are tiny particles of copper embedded in the plastic where the enameled wire should be and there is soot all around.I expected the electronics downstream of the transformer to be dead, but was pleasantly surprised when the system came up under the care of a current-limited power supply. Clearly there was some kind of protection in play.I have contacted GW Instek to see if they will recommend a replacement and will post their response when it arrives.

author: kripton2035
author_rank: Super Contributor
timestamp: May 07, 2012, 08:26:50 pm
content: can you measure the resistance between the primary windings ?I would in your case try to tear down the transformer, and remove one-10 turn of the primary,and then try to re-make these primary connectors.your transformer will not risk more than death ...