Linear PSU upgrade

Thread Starter

nmmnmm

Joined Mar 7, 2014
10
Need advice on upgrading old Lambda LINEAR PSU with Mean Well QP-150F Switch Mode PSU.

Lambda connections (on motherboard)
ANA 0v
LAMP (steps down -15v to -6.2v for exciter lamp)
-15v
+15v
+5v
0v
Raw DC Com

SMPSU connections
V2 +15v
COM
COM
V1 +5v
V1 +5v
V3 +24v (not required)
V4 -15v
(E)
(N)
(L)

Where do the 3 three Lambda cables go? (ANA 0v, 0v & RAW DC COM)
 

MisterBill2

Joined Jan 23, 2018
18,498
It seems like this is a REPLACEMENT, not an upgrade of a Lambda power supply. I see no mention of the AC mains supply to the Lambda power supply, so that leaves a big question: Is the supply being replaced AC mains powered? or did it receive DC power from some connection????
 

MisterBill2

Joined Jan 23, 2018
18,498
What is wrong with the Linear supply? Is it defective? or just replacement because of age/type?
I DID see a Lambda power supply fail once. It was brought to me for repair. THE FAILURE WAS that the over-voltage module on the terminals in back was set too low. So I was able to "fix it"
 

Thread Starter

nmmnmm

Joined Mar 7, 2014
10
I have a 19" rack with various boards that slot in a 'motherboard'. IEC Mains cable supplies a Linear PSU (Farnell 16RB / 5v Int Power IHC5 or similar). Next to which is a 15v Linear PSU (Lambda LOD-W-152 / XP LNBB15 or similar). the -15v psu is fitted with a non-oem regulator supplying -6.2v to a lamp.

A repair used to consist of replacing the electrolytic cap's. However, that's not always the case now, and sometimes it can take ages with a solder sucker on the Power Transistors sometimes ending up lifting the pcb tracks. The Lambda i removed recently had now been powered down for nearly 20 years.
 

AnalogKid

Joined Aug 1, 2013
11,042
Is the motherboard actually a passive backplane? If so, is it for one of the industry standards?

Is the system powered by linear supplies because of noise sensitivities? If so, then external filtering will have to be added to a switching supply replacement.

You don't mention the listed or required output currents.

Some of the Lambda or MeanWell connections might be for remote sense. Is there a system wiring diagram showing how the supply is connected?

Also, there are a lot of linear supplies available today. Why not just replace the lambda with a similar device?

ak
 

MisterBill2

Joined Jan 23, 2018
18,498
"Lambda" has been making good power supplies for at least 50 years and so there is a huge number of models. AND it is entirely possible that one that has not seen a sheltered life does suffer needing repairs frequently. AND, Certainly, for a set of voltages that will be set and not changed, fixed voltage linear supplies could be a very good replacement choice.
 

MisterBill2

Joined Jan 23, 2018
18,498
I NEVER use a SMPS in any industrial application if I can help it!
I have used adequately rated switchers from reliable product lines for the high current applications for many yr=ears, with no problems. But the ones I used were NEVER from web searches or yootoob recommendations.. ONLY from sources that had long before earned my trust.
 
Top