# Help! Old School Lanzar Opti Drive Plus 100 goes into protection



## Buickmike (Aug 10, 2012)

I posted this in the Old School forum, but then realized it would be better posted here. I'm just going to start a new thread with all the details to date.

I got my old Opti Drive Plus 100 from a buddy a few weeks back. This was mine back in HS. I powered it up and saw that it starts out in protection mode for a couple seconds, comes out of protection mode for a couple seconds, and goes back into protection mode again. It does this with nothing connected. If I hook it up to speakers and an audio source it plays loud and clean for those 2 seconds it is not in protection. It won't come out of protection mode the first time I connect it to a power source. Only every time after. A good Opti Drive will go green immediately no matter what.

So..I decided to take it upon my novice self to figure this out. 

I remembered that back in the day a couple diodes in the power supply section got hot and unsoldered themselves from the board. I soldered them back in and did not have an issue after that. I went ahead and pulled them to check them. They are fine.

The big caps in the power supply had scorch marks on them from my solfering iron (I was a teenager when I did that). I replaced them. No luck. While checking continuity I noticed that the ground side on one of the biggest caps was not connecting to the trace, which was common ground. After a couple attempts to fix this, I ended up just running a lead from the cap to the ground to see if that was it. Nope.

I pulled the mosfets off the board and checked them. One had leads that were about to break and another would keep losing resistance when I checked the closed circuit after closing the gate. I bought new mosfets and that did not help. 

I pulled the output transistors and checked them too. They all test out identically.

There are no scorch marks on this board.

I tested all the little caps on the board and they all seem to at least be functional. None are shorted or open.

My next step was going to be to replace all the little caps hoping that one is dried out and cannot hold a charge. Am I heading in the right direction, or am I missing something?


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## Buickmike (Aug 10, 2012)

*Re: Help! Old School Lanzar Opti Drive Plus 100 goes into protestion*

Anyone?


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## ATOMICTECH62 (Jan 24, 2009)

*Re: Help! Old School Lanzar Opti Drive Plus 100 goes into protestion*

My first thought is there is low level DC offset on the output which would let it play till it swings above the threshold on goes into protect.
I've never worked on one of these amps so its just a gut feeling.
You need a scope to see it.


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## TrickyRicky (Apr 5, 2009)

*Re: Help! Old School Lanzar Opti Drive Plus 100 goes into protestion*

Just a thought, have you checked the thermosistor/s or the ICs?


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## Buickmike (Aug 10, 2012)

*Re: Help! Old School Lanzar Opti Drive Plus 100 goes into protestion*

The thermistor tested out fine. At this point I don't have a scope, data sheets for the IC's, or even know what to do if I had all that. I was hoping it would be something simple that I could replace and test with a multimeter. Someone suggested a cap in the preamp section bleeding off DC and causing this. Should I bother spending another $15-$20 to replace all the small caps, or should I just hand this off to a pro to fix? There is a local guy who is a former PPI tech who could do it, or I could ship it off to Steve Mantz. I got an Opti Drive 50 Plus on Ebay and it works great, so I want to have a pair for an old school setup I will be putting in my Grand National.


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## TrickyRicky (Apr 5, 2009)

Replacing all of the caps is always a good idea & investment if you plan on keeping it, those caps did their job but they are old and will eventually fail with time, if they havent already failed.


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## Buickmike (Aug 10, 2012)

Ok. I'll replace the rest of the caps and see where that gets me. The fact that it comes out of protection for a moment and goes back really makes me think that a cap is not holding a charge.


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## spooney (Nov 5, 2010)

Post all of this same info over here: Car Audio - diyAudio

There are a few very seasoned techs over there that I am sure will be able to help you get this thing going strong again.


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## TrickyRicky (Apr 5, 2009)

perry & my good friend help diyers over there, and are very good at it.


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