Help with Lambda Power Supply ... $224 for regulator IC?
David Lee
The regulator/comparator IC gets *real* hot and I assume the IC is bad.
Called Lambda and they want $224 for the chip! The only
marking on the chip is their own (i.e. no National Semi number, or other);
FBT-00-128. It is a 10 pin TO-100 can. It appears to control parallel
pass transistors in the output circuit via yet another pass transistor
hooked to a 12V regulated supply. I can't match the IC it to anything yet.
Lambda won't help any more through their customer service. I have even
written to the engineering department.
Any advice is very much appreciated.
--
David D. Lee, AB5AX dd...@neosoft.com
Houston, Tx Cserv: 71330,2022
"Take 2 aspirin and call me at Turtle Island..."
Bob Parnass, AJ9S
David Lee <dd...@neosoft.com> wrote:
>I have a nonfunctioning 0-20V 3.3A Lambda LQ-521 Powersupply.
>The regulator/comparator IC gets *real* hot and I assume the IC is bad.
>Called Lambda and they want $224 for the chip! The only
>marking on the chip is their own .....
I went through the same thing with a different model, fixed
voltage, Lambda linear supply a dozen years ago. The regulator
was a big, ugly module built on a slab of metal and Lambda
demanded an obscene price for a new module.
I had the last laugh by replacing the ugly, proprietary module with a
simple 723 regulator IC and a driver transistor mounted
on a small perf board and it's worked like a champ since --
It is more reliable and maintainable than the ugly module ever
was. :-)
The 723 is a flexible, low cost IC which can be configured
for fold back current limiting. It's been around for years.
I've built several power supplies using simple 723s and various
configurations of 2N3055s. Just make sure you bypass all
this stuff well if you use it in RF fields.
--
==============================================================================
Copyright 1995, Bob Parnass, AJ9S par...@att.com
Locate transmitter sites with RadioMap(tm)
James Coulter
>From: David Lee <dd...@neosoft.com>
>Subject: Help with Lambda Power Supply ... $224 for regulator IC?
>Date: 29 Jul 1995 06:22:15 GMT
>I have a nonfunctioning 0-20V 3.3A Lambda LQ-521 Powersupply.
>The regulator/comparator IC gets *real* hot and I assume the IC is bad.
>Called Lambda and they want $224 for the chip! The only
>marking on the chip is their own (i.e. no National Semi number, or other);
>FBT-00-128. It is a 10 pin TO-100 can. It appears to control parallel
>pass transistors in the output circuit via yet another pass transistor
>hooked to a 12V regulated supply. I can't match the IC it to anything yet.
>Lambda won't help any more through their customer service. I have even
>written to the engineering department.
>Any advice is very much appreciated.
>--
>David D. Lee, AB5AX dd...@neosoft.com
>Houston, Tx Cserv: 71330,2022
>"Take 2 aspirin and call me at Turtle Island..."
I had exactly the same problem with trying to find one of those Lamda
regulator chips. I think I solved the problem either by finding another
unit that was junked, or replacing the elaborate Lamda supply with something
like an open frame power supply and a voltage control wired into the sense
lines. As far as I know, and I looked into it also, there is no equivalent for
that chip. Good luck,
Jim Coulter
Electronics Shop
Chemistry Dept.
VPI & SU
Doug Ripka
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>From: par...@radioman.ih.att.com (Bob Parnass, AJ9S)
>Newsgroups: sci.electronics.repair,sci.electronics
>Subject: Re: Help with Lambda Power Supply ... $224 for regulator IC?
>Summary: dump the overpriced Lambda chip for a simple 723
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>Date: 30 Jul 95 02:31:47 GMT
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>I had the last laugh by replacing the ugly, proprietary module with a
>simple 723 regulator IC and a driver transistor mounted
>on a small perf board and it's worked like a champ since --
>It is more reliable and maintainable than the ugly module ever
>was. :-)
>The 723 is a flexible, low cost IC which can be configured
>for fold back current limiting. It's been around for years.
>I've built several power supplies using simple 723s and various
>configurations of 2N3055s. Just make sure you bypass all
>this stuff well if you use it in RF fields.
>--
I'll second the use of the 723 regulator. I recently fixed a power supply
that uses a 723. It uses 4 2n3055 pass transistors to produce up to 22 amps
of current, and a voltage range of 6 to 15 volts. However, according to the
databook, the regulator circuit changes when you go from a 2 to 7 volt range
up to a 7 to 30 volt range. This power supply solved that by using a relay
that kicks in around 10 volts to change the regulator setup, which involves
changing a couple of resistors. Another option might be to use an LM350
monolithic regulator. Good for 1.2 to 37 volts max, and 3 amps if memory
serves. If these specs are acceptable, then it might be the way to go.
Doug