Autotek 99 - Strange repair by previous owner


Junior Member
Apr 23, 2017
Hi guys. At first i must admit that English is not my native language. I know its not at good level, but i hope you can understand what i mean.

I recently bought an Autotek 99 car amplifier, made by Zed Audio 1994.

(The PCB board tell us its Revision C which i cant find on google image)

It cost me 25$. I saw that couple of them was sold on this forum for 100$+, so i thought it was a good price. Seller told me that he is not first owner and he dont know if the amp was repaired, but its fully working. I bought it without asking for photos of inside, just to not waste time (someone else may take it in any moment)

I connected an amp when it arrives. both of two channels works identically, there is no crappy sound or distortions (i only tried to playin at 2/10 of volume, but i hope thats enought to say its working correctly)

When i opened it i did sad face, because it was repaired by someone.

i removed the IMG tags because photos are too big

1. Somebody added a capacitor (Nichicon 3300uF 35v). It's probably connected between B+ (12v) input signal and this small black diode.

2. The coil is also smeared with silicon (maybe to reduce the noise of coil?)

3. Im not 100% sure, but also some of the left side transistors looks like they was resoldered (i cant look closer, cause i dont know how to remove those black clips between the transistors and metal. They are very strong and i won't to break anything.)


Can you explain what somebody wanted to achieve by adding this one more capacitor?

Transistors looks like resoldered.. Is there chance that somebody inserted a fake's transistors? If yes, does it means that amp is worthless?

I have a chance to replace this Autotek for used Boston Acoustics GTA802, fully working in a good condition. Shall i do it? Im looking for strong mono/2channel amp for my rockford fosgate sub. Which of those two will be better?

Also, shouldnt the input level potentiometer act like regular volume control?

I mean if i connect this amp in home (i dont have my car audio completed yet), to the PC using 2x cinch > jack cable, even if the input level on amp is at minimum and the windows control is at 20/100 it sounds loud. If i set a input level higher volume get increased by little, so the potentiometer by self is working.

If you need additional informations or photos, just tell me. I would really appreciate your help. I'm starting my journey with Car Audio.

More photos:



Hurtin' feelings errrday.
10+ year member
Jul 24, 2005
I'm confizzled. So if the amp works fine, why worry who did the repair?



Jan 8, 2017
btw lots of those coils have some type of maybe it's silicon idk from the factory but some of that is to protect from moisture


audiobaun Veteran
Jun 28, 2011
I have 4-99s,2-66hcs,2-66s,2-44hcs,4-44s,2-40mxi,-2-60 mxi,and 1-90 mxi, and all have lasted me from the early 90s up to date.If you want to go back to the reg. board or have it repaired to original state, not going to happen more than likely, but you can get close, by sending it to Zed Audio.Im a Zed amp collector, and have enjoyed every amp made Ive purchased over the years.Hard to let them go as they are full of surprises and sound so clean.That 99 will run 1 ohm mono stable if you keep it running cool.One of the Best amps ever made in my opinion.I plan on setting up an Old Autotek Mean Machine Install, and then Autotek Bass Thrust,Both great amps.The individual that rebuilt that board looked as if he was trying to get it back up and running.If it works..Run It!



Junior Member
Apr 23, 2017
AMP is working corretly under mine 2x Tonsil perfect 150 (150w 8ohm each connected in parralel) but im afraid that if it was repaired, it may be not that stable or powerful than the original.

I will give it a try and connect it to an 1ohm subwoofer, lets hope that will be stable. I won't damage my speaker..


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