2008-02-23
The purpose of this webpage is to describe the behaviour of an Ericsson 27 V rectifier I bought, and that I doubt is working.
If you have any ideas on how to get it to working as a normal SMPS please contact me. Thanks in advance.
Below are a number of observations and measurements I have done on an Ericsson BML 435 002/1 rectifier that is capable of delivering 27 V and up to 50 A (1200 W).
When plugging the rectifier into the mains outlet the voltage, on the output terminals, immediately goes to about 33 V even if the On/Off switch on the front plate is in Off-position. It takes about 30 min before the output voltages reached below 2 V, without load. With load the voltages drops faster.
When switching the rectifier On the voltage goes to around 27 V but with a lot of fluctuation, from about 26,2 V to 28,9 V. The latter makes the otherwise nice and robust looking rectifier useless as a power supply :-(
Fig 1. DC voltage behaviour of the Ericsson BML 435 002/1 rectifier. Source: own measurements.
Here is a video sequence, 7,5 MB, of how the voltage fluctuates.
When the rectifier is off the "Communication" LED flashes fast but when the rectifier is turned on the "Communication" LED still flashes but at a slower rate.
After more than 60 min the Error LED turns on.
So what is wrong? Voltage sensing terminals not connected? The Control Unit is needed? If you can help please do.
Fig 2. Ericsson rectifier control unit.
Well, according to Christer, SM4FXR, the Control Unit should not be needed for normal operation. But it might be needed to change the voltage. Alternatively a modification may be performed on the control board.
Fig 3. Modifications of the rectifier control board to make the output voltage adjustable on a pot-meter. Source: Christer, SM4FXR.
Here is a schematic or a PDF-schematic (2,5 MB) of the rectifier. I found a Spanish document about the rectifier on Google and I have made this Babelfish English translation.
Fig 4. The control board.
According to Bart, PE1PFW, changing the 78 kΩ resistor to a 100 kΩ potmeter will make the output voltage variable between 15 V and 33 V.
Fig 5. Backside of the Ericsson BML 435 002/1 rectifier.
2005-08-01 Mats-Ingvar, SM4DXO, says: "I have been recommended to use two car battery in series over the output and also about 15 Ω in parallel over the output. I got this information from Hans, SM3LWP, who has been working with it on Ericsson."
2005-08-01 Håkan, SM7GEP, says: "It doesn't sound as if it is working properly. I got some myself and only one of them behaves like yours. However, all are OK if loaded with minimum 1 A. I also use the 'bouncing' SMPS for a 1 kW DC PA without problem. It seems to work UFB and the transistors can easily handle 30 V. I also recommend to use a bleeder resistor."
2005-08-03 Bo, OZ2M says: "I have now tried to load the rectifier with a 54 Ω resistor. I do not have a lower value that can handle the power. When doing so the voltage stays at the set level for four to five hours without any fluctuations. But then the Error LED turns on and the voltage starts to fluctuate again. Switching the rectifier off for a minute and then back on again the rectifier stops fluctuating but reverts to it again after some more hours."
2005-08-14 Per, SM0DFP says: "What you got is a battery charger not a power supply! You have to connect a battery as load. I have used a similar supply for years that is connected to two lead acid 16 AH batteries. Do not use the charger without any battery connected. Otherwise you will see exactly what you are experiencing which is inappropriate for supplying transistor PA etc."
2005-08-15 Bo, OZ2M concludes: "Well so much for the 90 € spent, excluding transport costs :-( Even if I can connect a battery as load it is not what I had in mind and not directly my application."
2005-09-28 Michael, DG0OPK mailed me saying that he too has a malfunctioning Ericsson rectifier. He did a lot of tests with it and also investigated the circuits but concludes that his is not working as a normal power supply either.
2005-11-11 Bart, PE1PFW says: "I've also bought such a PSU two years ago. Mine doesn't behave like yours. When I plug in the AC no LEDs are switch on and no voltage appears at the output. When I flip the switch the nominal voltage (24 V) appears at the output and is well regulated. The communication LEDs are not on. The communication link appears to be a simple RS-232 connection. Unfortunately there is a password protection which I don't know. Therefore I cannot change any settings. I have asked Anders, SM7ECM, about it and he seems to know more about it, but could not tell me that time, maybe he can now."
2005-11-26 Gerhard, DH9KHG writes on a German bulletin board: "Is the Ericsson BML 435 a charger? Has OZ2M mishandled his power supply so it is now defective?"
2003-12-03 Bo, OZ2M comments: "Well Gerhard, DH9KHG, according to Ericsson's schematic of the 'device' it is a rectifier. I graduated as an electronics engineer in 1987 thus electronics is far from unknown to me."
2005-12-03 Gaëtan, ON4KHG sent me a mail with a series of correspondence between him and Gerhard, DH9KHG (what a foul language!). In this Gaëtan, ON4KHG, highlights that his and a handful of French hams' rectifiers are behaving just like mine and puts Gerhard, DH9KHG, attention to my webpage. Interestingly Gerhard, DH9KHG, states that my unit is defective. But when I mailed him about the odd behaviour in early spring 2005 he said he had tested it thoroughly before shipping it to me also saying that there was nothing wrong with it. But he has never contacted me again apologising and replacing my malfunctioning rectifier.
2006-09-20 Bo, OZ2M says: Is this the same person selling Ericsson rectifiers as Ericsson Schaltnetzteil on eBay? If so then he seems to have changed identity three times, DH9KHG, Kuvin and Kuegue. Why? It the ground burning? Please correct me if I am wrong.
2006-11-25 Bo, OZ2M says: Just discovered that eBay ID Kuegue was changed to zugdurch. Looks a bit suspicious, doesn't it?
2007-12-14 Bo, OZ2M says: Today my attention was drawn to the fact that the callsign DH9KHG has never been issued in Germany. http://ans.bundesnetzagentur.de/amateurfunk/Rufzeichen.aspx Therefore not only are questionable products sold also the identify is false.
2008-02-23 Bo, OZ2M says: Today I found the following new text on Funkboerse: " 29. Biete UKW-Geräte (Anzeigen-Nr.: 247990) Tebechop Schaltnetzteil 48 - 57 Volt 30 Amp. Tebechop Schaltnetzteil DC = 48 - 57 Volt einstellbar über Poti und 30 Ampere. In 230 Volt über Kaltgerätebuchse. Preis 150 ink. Versand. Habe neue E-mail Adresse !!! Oder die alte DH9khg@arcor.de :-) 21.2.08 - 16:50 Uhr G. Küpper - Tel:02421 277118 dh3pr@arcor.de." Very interesting is it that a new callsign is used in the second e-mail address: DH3PR. This callsign refers to Peter Reissdorf in Elsdorf.
Bo, OZ2M, www.rudius.net/oz2m
