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Zx350 OVL then Steady Green after cap repair

Posted: Mon Apr 05, 2021 3:25 pm
by GettinOlder
Ok, so I replaced the power caps and rail caps. I think everything went well but I energized the amp and the the OVL turns on for a second, the fan stops and then powers up again and get the green light. It stays lit and fan runs. This is with no speaker connected. So I then connected a speaker on one channel (left) and no sound. (Only tested this channel). I adjusted the gain pot and no sound (per say) but get static as I change the gain. The static sound pops here and there and does increase in volume as I increase gain. If I turn the gain all the way up, it turns off!? I’m using a little 12V power supply to test (didn’t want to use a battery or the car itself in case if blew up!). Should I use a proper 12V source (battery)? But checked the voltage at the rail caps and found 38.7 Vdc each cap. Any ideas?? Where I can start testing this Zx350v1 by the way. Thanks!!

Re: Zx350 OVL then Steady Green after cap repair

Posted: Wed Apr 07, 2021 2:32 pm
by Jacampb2
Overload led for a few seconds and then green led is normal startup behavior. The o/l led is lit while the poweramp is muted during power up. This is to keep any pops or thumps from hitting the speakers.

The amp can easily overload a small DC power supply. You can run a more stout supply and either a 2R current limiting resistor or a serious 12v headlight bulb and it will save your bacon if there is an issue.

Why there is no audio, well, if you pulled the rail caps, I'd bet money on board damage. If you compromised the through hole plating both rails will not be present everywhere they are needed.

Other than that, the ribbon cables are common failure points as are the configuration switches. Double and triple check that the crossover is configured correctly.

Re: Zx350 OVL then Steady Green after cap repair

Posted: Fri Apr 09, 2021 4:31 am
by GettinOlder
So I have been doing a lot on this amp and keep finding little issues. I have also visited another forum on fb and learning a lot. So far I have pulled both bass boost and gain pots, opened them up, cleaned them up with deoxit and made major improvements. Then ended up breaking the ribbon cable solder joints on the daughter board and ended up replacing with wires instead. Also, I pulled the fan, heatsinks, isolation plates and removed the old compound on the chips and replaced it with dowsil 340. Now all my channels have music and no static, thumps or pops while sweeping the gain. But my left channel is clean and performs well, my right channel seems to have some distortion. I bypassed the daughter board as a test and connected the mainboard XVR interconnect pin 8 (right channel signal) and pin 2 for shield to my rca input and made a huge improvement so I will remove my daughter board completely and put individual RCA jacks Jason recommended (his knows his stuff and boggles my mind!). I get a little thump while shutting down the amp still so I'll now checking my fusible resistors and see if any of them are open. The saga continues! Once I get this project over (I can feel it in my bones that the end is near) I'll post some progress pics and part #'s so I can help the phorum community in case someone else needs help. Stay safe.