Aeroflex IFR3413 IFR3414 IFR3416 Signal generator PSU - Page 1
Forum section: electronics / testgear

author: G0HZU
author_rank: Super Contributor
timestamp: August 11, 2023, 09:38:59 pm
content: HiHas anyone in the UK got an Aeroflex IFR3414 sig gen they can do a quick test on for me please?I've just repaired the switching PSU in one of these and it would be nice to compare VA and W readings from UK 230V AC mains when the sig gen is running normally.The datasheet says <185VA but this is for all models. Mine is a fair bit less than this but it would be nice to know the readings for a known good generator.The power supply is one of the TDK Lambda Sirius CSF250NMML types as shown below. The image below is from my 3414 sig gen.The reason I ask is because the PSU is really complex (to me anyway) and I had to change quite a few dead parts to get it working again.It looks OK with a thermal camera with the cover removed and since the repair, the sig gen has been on soak test for many hours and it's still OK.Thanks in advance for any replies...

author: Mkpirulo
author_rank: Contributor
timestamp: June 08, 2024, 08:27:58 am
content: Hi, do you still need the power supply info?Michael

author: Mkpirulo
author_rank: Contributor
timestamp: June 08, 2024, 08:33:51 am
content: Hi again, air flow through the power supply is very important. The original foam needs to go around the supply so when the cover is on the air can only go through the supply.Michael

author: G0HZU
author_rank: Super Contributor
timestamp: June 08, 2024, 09:41:49 am
content: Quote from: Mkpirulo on June 08, 2024, 08:27:58 amYes, thanks! It would be nice to know this although I now have several of these 341x sig gens here. I try and keep a W and VA power spreadsheet for all my test gear.I typically see 15W and 21VA in standby and once it has been powered on for maybe 10 minutes, I typically see 123W and 132VA. How does this compare with your sig gen?

author: dew
author_rank: Contributor
timestamp: June 13, 2024, 09:36:07 pm
content: They do get themselves cooked sometimes

author: Mkpirulo
author_rank: Contributor
timestamp: June 13, 2024, 10:29:49 pm
content: Yes, this cooked area is typical due to ambient temperature to warm. When these are in a lab with AC at 72F this area will not be to bad but if you run this at home room or garage you can be 15F higher in temp.. Read my post from yesterday, I’ll see if I can find the link. Those SMDs with no fan running (standby) mode they run at around 100C ambient at 28-30C. Michael

author: Mkpirulo
author_rank: Contributor
timestamp: June 13, 2024, 10:36:30 pm
content: Ok see my post to another group about this issue.Re: IFR 3414 Signal Generator Repair (spurious signals on output)Michael K.Jun 12Hi Gents,I have four or five different manuals/data sheets on these supplies. One manual states that it needs a fan even if the PSU is On but there is 0 load (when using the enable control of the PSU via the molex connector).Always thought that was strange so I dis-regarded it just to have it bite me in the rear, let me explain.My first 3413 five years ago had a PSU that had the SMD resistors under L12 burned, actually the PCB was burned very badly due to those resistors heating up (90 - 100C). This location is at the edge of the PSU that faces the fan. But at the time I thought that the supply just burned up due to a bad fan, I’m sure that did not help things. Since I did not have any schematics I purchased another supply that had basically the same PCB as mine. This allowed me to do a few resistance measurements of a known good unit. Even though the PCB was burned I found an open trace in this area. Fixed the trace and also replaced all of those SMDs. Turned the unit ON and it worked. Put it back together and put it back into the rack. Plugged it in and left it on standby to keep the 10mhz oven on. After a few months I noticed this smell, did not really know where it was coming from. Until it became so bad I had to track it down. Well it was the PSU again at that location. This time I replaced the entire supply with a new one, known good. It turns out the new one was also getting hot at the same location, strange. I verified this temperature on my other working 3416, same temp. Another printing of the manual does not mention that cooling is required at 0 load. On the 3413 the fan pulls air through the PSU but on the fan versions of the PSU (EM and TM) the fans blow in onto the PSU as soon as AC is applied (when the enable molex is used) to the PSU (Let’s say as soon as you turn the rear switch on to the 3413, fans would be running to cool this area down).In the 3413 even though it gets AC power as soon as you turn the rear switch On there is no fan that turns On until you push the button on the front panel. These supplies are slowly baking when in standby mode. Look at your PSUs I’m sure that the location is discolored at best.On top of this you guys are also seeing temperature issues as well. I can understand some of the over temperature signs are coming from environments that are warmer than your typical electronics lab, We don’t have AC running all of the time. This would mean that the temperature mitigation is marginal.If your unit is in a warm room don’t leave it on standby turn it off.Another way that might work to cool it down while in standby is to take the fan leads that cool the PSU and plug them into the PSU fan terminals. The fan would turn On as soon as the rear switch to the 3413 is turned On. This PSU fan output runs the fan at the same speed as the 3413, slow with very little noise. When the PSU gets warm it will speed the fan up like the 3413 fan control. Not sure if the 3413 might sense a disconnected fan.Well hope this helps to shed light onto the marginal heat mitigation of this unit.Last comments would be on finding good CSF250 supplies that would be a fix for any bad original supply. If you have a bad supply that can’t be fixed, don’t throw because you will need the transformer out of it.MichaelOk this is what I posted yesterday.I have two 3416 and one 3413, all have the same heating issue.Your thoughts?

author: dew
author_rank: Contributor
timestamp: June 14, 2024, 12:43:37 am
content: Nice summary, Mkpirulo. Looks like a shortcut in the supply design. They tried to cram it all in one nice SMD board. Current shunt is made out of two beefy through-hole resistors, but these... They heat up almost instantly and stay hot all the time.https://youtu.be/WT7ck5aMVWM

author: G0HZU
author_rank: Super Contributor
timestamp: June 15, 2024, 09:09:44 pm
content: I think there may be different PCB revisions used in these PSUs because I don't recall seeing those big SMD resistors in the last 3414 PSU I repaired.I recall that it had large white rectangular (ceramic?) through hole resistors in that location. It might be worthwhile to modify your PCB to be the same? They were quite big resistors, about the same height as the blue capacitor C13 in your image. Maybe twice the width as C13 but with the same depth as C13?

author: Mkpirulo
author_rank: Contributor
timestamp: June 17, 2024, 03:27:59 pm
content: Hi, Yes that’s what I’m talking about. Send me the model of the supply with the two ceramic resistors, is it on a CSF250 supply.

author: G0HZU
author_rank: Super Contributor
timestamp: June 17, 2024, 04:34:56 pm
content: Quote from: Mkpirulo on June 17, 2024, 03:27:59 pmLooking at my records, it's the same CSF250NMML model as the one shown in post #4. The part numbers on the main label are identical.I don't really want to take them both apart as there are lots of screws in the PSU cover plates but I think both of my CSF250 PSUs have the two large white through hole ceramic resistors. I spent a fair bit of time repairing one of them and there were no large 10k SMD resistors on the underside of the PCB.I have some internal images of the processor board and the RF board and some of the chips have 2005 date codes. However one PSU was dated 2016 and one was dated 2009 so I suspect both of these PSUs are not the original PSU fitted to the sig gen. Maybe the original PSU had the SMD resistors and it failed in some way?

author: G0HZU
author_rank: Super Contributor
timestamp: June 17, 2024, 04:44:29 pm
content: I should have some images of the insides of these PSUs somewhere but I probably won't be able to tell if it is the 2009 PSU or the 2016 PSU. I have various cameras here (phone, camcorder, digital cameras) and a several memory cards for two of them. The images should be one one of these devices. However, at least one PSU definitely had the large (white, square, vertical) ceramic resistors either side of the inductor that looks a bit like a transformer. I strongly believe they were both like this.What is strange is that my PSU date codes are 2009 and 2016 and the PSU in post #4 is dated 2014 and they all have the same part number.

author: Mkpirulo
author_rank: Contributor
timestamp: June 18, 2024, 04:24:12 pm
content: Interesting that psus have the same number but different fabs. All of my PSU have date codes on the green sticker. Mine are 2002 - 2006 vintage. I will be attaching my PSU fan to the fan terminal inside the PSU this is the best location to control PSU temperature. The main 3413 board has no direct feedback on PSU temp.. I will also replace the main boards fan with one step up in cfm. Original fan is the 622HH. The rubber fan mounts can be replaced with like ones from Amazon. One will need to cut the original ones to get the fan out. Attached are some pictures of my PSU, I should say my bad one. I removed the transformer and transplanted it into a working board. The original transformer has the low leakage current that the model number states.MichaelKD6UJS

author: G0HZU
author_rank: Super Contributor
timestamp: June 18, 2024, 05:06:53 pm
content: I managed to find some internal images of two of my PSUs. See below.The image that shows the whole board is from the 2009 PSU as pictured in my original post in this thread.The closeup image must be from the 2016 PSU as it shows some differences in terms of the red sealant. So this is not the same PSU captured twice.There is another white ceramic resistor on the other side of the inductor/transformer in both cases.

author: Mkpirulo
author_rank: Contributor
timestamp: June 18, 2024, 10:11:41 pm
content: Hi,Yes interesting, looks like TDK realized that they had an issue with the earlier models. I would guess that you might see the same temperatures but these can easily handle the temperature. Would be interesting to see how hot the inductor gets between the two resistors. When the unit is sitting in standby mode it’s still warming up but it will no longer burn the board, might heat the inductor. If I had this supply I might still change the fan control configuration just to protect the inductor.My opinion is that one would want to control internal heat on these obsolete gens since parts are hard to find.My Agilent E4418B and 53143A have their fans running when plugged in.Thanks again for taking the time to send pics.Michael