# Lanzar Opti 4001D Repair - No Power/Possible PSU Troubleshooting



## laughatthemall (Aug 3, 2015)

I am dealing with an Opti 4001D that was given to me with the original issue of the 38N30 outputs being blown on one side. I have replaced that side and the associated gate resistors, and now get no indication of power whatsoever. It draws 0.0A after initial capacitor charging. It appears not to use a TLx94 chip for PWM, but a KA3525A chip. The datasheet for that is here : http://www.mouser.com/ds/2/149/KA3525A-1010657.pdf

KA3525A Voltage (vDC)
1.) 0
2.) 5.05
3.) 0
4.) 0
5.) 2.10
6.) 3.63
7.) 2.10
8.) .333
9.) 5.52
10.) 0
11.) 0
12.) 0
13.) 12.02
14.) 0
15.) 12.02
16.) 5.05

I have attached any 'interesting' (non-DC) waveforms I found on this IC (Pin 5/7, same waveform). Plus, bonus internals / gut shots of the cadaver, just in case it can help someone else in the future.

IRF064N has ~12v on the Drain (center) pin with or without remote applied. There is no waveform on any of the three terminals (or rather, only a straight DC waveform).

All measurements here are taken with ground being referenced to B-.

Any of these look 'off' to you? Any suggestions on my next course of action? Thank you for any help you might be able to provide!

EDIT: Just re-read the SMPS section of the tutorial. Found the information for the SG3525, and noted that pin 8 is not as it should be (near 5 volts). Pin 4 also appears to be incorrect (no pulse?) Pin 11/15 has no output either. Now to figure out why; any way to determine whether this indicates bad IC or something else?


----------



## laughatthemall (Aug 3, 2015)

Here are the promised internals pictures. Hope it helps someone!


----------



## bnae38 (Oct 3, 2015)

pin 10 is shutdown and is low?


Unless I'm mistaken.....

I would start there


----------



## bnae38 (Oct 3, 2015)

Test circuit in datasheet seems to pull it high to shutdown, misleading... if your tutorial had that low, odds are it should be, nvm....


Softstart should just go to a cap or rc that will charge (relatively slowly) before bringing outputs up on chip..

Sounds like it could be a bad chip (or cap... but not likely). Think you're on the right track.


----------



## laughatthemall (Aug 3, 2015)

Well, I got a bit further with this. I tried replacing the chip, to no avail. I did note that when I would apply remote voltage (I have it hooked to a switch) and watch the legs of the PS transistors, it would give a bit of a 'ripple' as if it is cutting out immediately. I pulled the output driver board just to see if that mattered, and yes. It now powers up and the green 'functional' light comes on when this board is not in it. I noted that IC part number IR2113 was socketed and removable, so I decided to remove it and see if that did anything; being that this appears to be one of the main things on this board and is the gate driver IC. With only this removed, the amp still functions what I would call as expected (PS has proper waveform and output), and draws 1.6A. Is there any way to test this IC to see if it might be the issue? It's a 5 dollar IC, which in the long run is nothing, but I'd rather learn how to definitively determine or get an idea if this is the issue or not, before resorting to low-tech 'replace and pray' methods.


----------



## laughatthemall (Aug 3, 2015)

A bit more info, I checked out the pins with the chip out, and most of the pins along the top row (8-14) have ~93v DC on them. This matches what the replaced transistors have on the center leg (the one side has ~93v on the center leg, the other side has ~-93v on the outer two legs).

I guess that's where I'm at now -- is it normal that many pins going in to this driver board have about 93v on them? I read the pins actually leading in, and it appears there are about 5 pins that have +93V on them.


----------

