Lambda linear lab supply schematics LP-414A FM - Page 1
Forum section: electronics / repair

author: jonpaul
author_rank: Super Contributor
timestamp: April 09, 2025, 11:14:21 pm
content: Hello, I am Seeking schematics and parts listLambda LP-414A FM 0-120v 0.2 ALinear lab power supply circa 1970sMany thanksJon

author: edavid
author_rank: Super Contributor
timestamp: April 09, 2025, 11:40:27 pm
content: See attached.

author: jonpaul
author_rank: Super Contributor
timestamp: April 10, 2025, 12:22:04 am
content: Edavid, many thanks for the fast schematicsPerfectAmicalementJon

author: coromonadalix
author_rank: Super Contributor
timestamp: April 10, 2025, 12:25:15 am
content: and the regulator ic is supposed to an mc1466 who's rare nowadays, fakes exists

author: jonpaul
author_rank: Super Contributor
timestamp: April 10, 2025, 03:57:08 am
content: It's dead due to shorted pass NPN TO-66 series pass regulator, I had a large charged lytic that discharged when supply was turned off.Jon

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 10, 2025, 06:03:36 pm
content: I rebuilt a Lambda 522 that i stupidly blew.There is a schematic for making your own mc1466, but I did not use that, I ended up using a few op amps, a zener for ref and I used multi turn pots for making voltage and amp adjusts easier.I think the zener is not as stable as I would like (millivolt drift with heating) and am thinking about a different volt ref.If you want I can post the mc1466 schematic and my own schematics for my "fix"

author: Puffie40
author_rank: Regular Contributor
timestamp: April 10, 2025, 08:31:15 pm
content: Quote from: Wallace Gasiewicz on April 10, 2025, 06:03:36 pmI would say go ahead and share it anyway - Someone in the far future might thank you for the workaround!

author: cnqhdszq
author_rank: Regular Contributor
timestamp: April 14, 2025, 08:35:45 am
content: FBT00128=LAS3700

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 14, 2025, 01:49:02 pm
content: The MC 1466 file is someones build of a 1466 using discrete components. I did not build this.The second attachment is a partial schematic of a voltage and amp control of a Lambda 420 FM PS. I did build this and it works. I believe that the Zener diode reference drifts a bit, perhaps a few milli volts. It is sensitive to temp and just blowing on it will cause noticeable voltage shift. I do not think this is meaningful but perhaps a more stable volt reference should be considered.I used multi turn pot also, rather than the two pot adjustment of the original.This was a project and not meant to improve the original. I blew the MC 1466 chip.I know the schematic looks simple but dealing with the two voltages and their interactions caused me to do too much thinking. I now have a better understanding of the complexities involved.

author: GGMM
author_rank: Frequent Contributor
timestamp: April 14, 2025, 02:07:02 pm
content: Hi, WallyLook here:https://groups.io/g/HBTE/topic/homebrew_power_supply/99852161This is an example of making a power supply. May be less sophisticated, but it works.I know you follow my constructions.There, it is still tinkering with my oscilloscope 54810.Hope to finish one daycdt

author: artag
author_rank: Super Contributor
timestamp: April 14, 2025, 02:54:49 pm
content: Quote from: coromonadalix on April 10, 2025, 12:25:15 amI've successfully repaired an LP-521 using an MC1566L. Differences seem to be small, I haven't looked in detail (the available datasheets are dreadful) but it may have a slightly higher voltage tolerance and is available, I think, from Onsemi if you want to avoid dodgy sources.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 14, 2025, 07:36:00 pm
content: if i recall 1566L is an higher voltage version ...

author: MarkL
author_rank: Unknown
timestamp: April 15, 2025, 10:53:49 pm
content: If of any interest, there are a couple of sellers with Motorola FBT-031 on ebay in the USD $10 range right now (pricey but not insane). FBT-031 (aka FBT-00-031) is the Lambda part number for MC1466L.I have a Lambda LPT-7202-FM with FBT-031 labeled IC's that I repaired with a MC1466L. Interestingly, the LPT-7202-FM service manual parts list says:IC101, IC201, IC301 Integrated Circuit FBT-00-031 **...** IC101, IC201, IC301 was FBT-00-034 onunits with Serial no. prefixes A & B.Mine is serial C02xxx. So, it's likely that FBT-034 could also be used, if available.No affiliation to the sellers.