lambda LLS6120 Power Supply IC needed

[rodd]

Hi folks,
I am trying to repair this power supply.
I could find the  instruction manual with schematics in the internet.
The primary side is not oscillating. After some checks and following the trouble shooting procedure described in the manual I could find that Q102 was opened.
Fortunately I had the replacement in my junkbok (an IRF840 ) but that did not solved the problem and no oscillation at all.
After checking Q103 (BUZ71), which was OK, the manual points to IC 101, where my problems begins.
This is a custom IC marked FBT00-116.
I checked the link on this blog that mentioned a Lambda catalog, but unfortunately the link is broken.
Does anyone have a copy of this reference or any idea of where I could by this part or an replacement?
Thank you all,
Roger

[orbanp]

Hi Roger,

You did not give the correct schematics! All the ICs are denoted IC2xx!
I downloaded the manual for the LLS6000 series regulated PSs.

Generally Lambda did not make their own ICs, just relabeled commercial ones.
It is also possible that they selected the ICs.
However, this IC indeed looks like a custom chip, as the pin-out is non standard!
Assuming that I am looking at the correct schematics, IC101 is a quad op-amp, but with that non-standard pin-out.
It is running from 15V, assuming the note is correct on the schematics.

I would take the old IC out, put in a socket, and wire in a "regular" quad op-amp, like an LM324.
You could also check out the old IC once it is out, test if they behave like op-amps.
If you know the resistor values in the circuit around those op-amps (I did not find any parts list) then you could decide if it needs a FET input op-amp or not.

Good luck, Peter

[duak]

G'day Roger,

I was thinking that I'd seen that IC footprint somewhere before.  I believe it is an LM339 quad comparator.  It makes sense because it looks as if the chip is generating switcher control pulses, probably above 20 KHz and that most of the outputs are pulled up to Vcc since the LM339 is open collector.

Best o' luck

Duane

[rodd]

Hi Peter,
Thank you for your comments.
There are two pages on the attachment, and the primary side is on the 2nd page - sorry for that.
There is no parts list in the version I downloaded also.
The resistors values around IC101 are:
R116- 10K
R117- 14K
R118- 5.6K
R120- 470k
R121- 15K
R128- 470K

Can you help me to choose the op amp to try?
Thank you again,
Roger

[rodd]

Hi folks,
I am sorry for my post.
I should have read the answer from Duak before.
I think I would try it and post the results as soon as I get them.
Thanks to you all,
Roger