So any help would be appreciated I have this ZX450 ver.2 white case not sure what happen but driving home from fireworks and the amp just cut out and I was not playing the stereo loud or anything but the next morning I noticed that the lights on the front was switching between red (ovl) and green (power) and its constant going back and fourth (red green red green). I have everything unplugged no RCA and no speakers wires connected to the amp so I could test for bad sub or what no luck. I disconnected the amp brought it inside for visual inspection after removing the front and looked at everything and nothing I had this amp repaired over 10 years ago (Licensed Dealer) shipped it and after a lot money to fix it due to brother borrowing it and had installed the power wire between the car door and frame it pinched the wire and burned up top right side. Other than that only other issue I have had was RCA plugged seems loose for front side I would loose sound on bottom RCA and would need to move it a little to work again.
Don't think this is the cause of your problem but very well might be. Those four large capacitors near the toroid/transformer are known to leak and cause severe damage (even fire in some cases). I wouldn't be surprised if you remove them and find a small trace underneath them or near them that has been damaged by the electrolytic fluid that is now OPEN. Seen it before, so I would start there and then re-test.
Okay I'll look into these and try and replace these caps! I hope these are the reason and will post back when replaced if anyone could help try and chime on to why it would switch from OVL red to power green on and off constantly that would be awesome thank you
Been running two 12 subs at bridge... I removed all connections to verify if it was a speaker issue and no luck on getting it to run Constant on power green only! So I order the replacement caps and I hope I ordered the right ones I saw a link from Erick http://www.soundbuggy.com/Eric/Car%20Au ... index.html about this issue so going off what he said I ordered those caps I hope I did correctly for those caps please let me know if I'm on the right track please
If you used Eric's link then you should be okay with size. Also don't forget to check the internal fuse, those may appear to be good but may have a loose connection inside on the ends. So do not check it with your eyes, use a meter.
So update on this is I checked fused on internal amp on meter said was good. I replaced the four large capacitors near the toroid/transformer and still no luck. I'm going to order the next four capacitors under the crossover/RCA board but I'm running out of steps trickyricky... Please help!!!! I thought they looked bad and after removal they seem ok but will still order new ones since they are out. I have seem other post on ordering bigger ones what do you guys think? here's the replacement link http://www.digikey.com/product-detail/e ... ND/5057745
Don't mess with the rail caps...it will not repair the issue. All the rail caps do is help filter the DC rails and as a capacitance bank. If you remove the black top off of all four and none are vented or bulged then I would suggest to leave them alone. Some damage the via's by pulling the caps while there is still solder connection on the pins.
Have you checked to make sure your power supply fets aren't shorted/bad? If they are good then check the large protection diode that's by the toroid (doubt this would be the case as it usually draws a lot of current if either of the two are bad). You'll have to check the fuse resistors for the fet drivers and PWM IC's pin outputs (11 and 14 I believe).
You are saying this amp is just cycling on and off repeatedly? If so check for DC voltage on the speaker output terminal, if there is a significant amount then the amplifier would go into protect mode and could cause it to cycle on and off. I would also check the remote input circuit as those can have bad transistors (the first two transistors on the remote circuit). There are several things that could cause the amplifier to cycle, so it may be hard to tackle this one but don't give up.
Rail caps are not bad then took the cover and none look damaged and if you could point me in the right area as what to check and how to check them please
Okay so check for DC voltage on the speaker output terminal front left and right are low .002 or close to that it jumps around but nothing high and the same with the rest except back right side jumps from 1.0 to 3.2 DC Volts so I would assume that this is where the issue is causing the amp is just cycling on and off repeatedly from green to red (OVL). Is this a output fet not the power fet and if so how should I check the voltage on these?
Yep if the dc voltage rises on one channel then you can rest assure there is an issue with that channel. The predrivers, drivers or the final output transistors may be shorted/bad, there are also fuse resistors near by these devices that need to be checked.
What channel was this? You'll have to carefully remove the board from the bottom chassis/panel.
Check between the legs of the output transistors with a meter either in diode or resistance mode. There should not be any dead shorts (meter will beep if set on diode mode, or read very very low if set in resistance mode). You'll have to check the predrivers and drivers as well, don't forget the fuse resistors that are near by these devices as well. They pop open and leave no sign or marks.
Each channel has a dedicated component part number...for example a resistor for ch1 would read R1xx while ch2 resistors will be labeled as R2xx. So if you have a problem with channel rear right (you can keep focus on that area/devices for that channel).
Looks like Rear Right ch is Q2xx/R2xx/C2xx. When ohming out devices and you think you found the problem compare your readings with another channel.
So an update found two output transistors was not showing the same as the others so I removed them and boom its staying in the power on mode and not switching back and fourth.. wow I'm so grateful for all you help in getting this old school working. I still need to get the replacements on these to fully check if this fixed the issue but from the test I think it has. where would I go to order the right ones. attached is the ones removed which was Q219 and Q218. Both were not showing the same as the others thru testing with the meter.
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IMG_7029.JPG (65.74 KiB) Viewed 12418 times
zx450 output fet right side.jpg (144.21 KiB) Viewed 12418 times
Great job did you notice how these transistors have a short between pins/legs? .Before you place an order make sure you check all the resistors in the channel. After that check the predrivers and drivers (compare to the other working channel) as well as the resistors around these devices.
I order my components from Mouser as they are about 11 miles away. Parts are Fairchild 2SC5200 and 2SA1943 (I suggest you order 2 of each...2SC5200OTU and 2SA1943OTU)
Also since you mention you are running it bridge I would suggest you replace the outputs of the opposite rear channel as well so both channels have outputs with matching characteristics.
Thank you, I wasn't expecting that and that's when I spend more time testing on each one to make sure I wasn't doing something wrong haha.. and yeah I'm going to order for each since that makes sense to do that. I will go thru and continue to check each resistors as far as checking the predrivers and drivers not sure on what I'm looking for and testing I don't think I saw that on that website you referred me to but I could be wrong...
The predrivers and drivers are Q214-215-216-217, check all the resistors in that channel.
Also once you confirm everything is good and solder in the new output transistors make sure to power up the amplifier with a 5-7.5amp fuse and if possible (very important) keep an eye on the idle current making sure it doesn't increase has to remain steady around 1-2amps. You'll more than likely have to adjust the bias for the new outputs (I'll let you know how later on once you got everything straighten out and ready to test/power up).
Make sure the black anodized heat sinks don't get scratched up where the transistors make contact with it. Otherwise you'll run into bigger problems.
Okay I found all but 217 maybe its just late but anyways Ill look at it tomorrow after work I'm hoping to have everything needed to order on Friday... Since you said replacing the other two output transistors which I agree on the other channel how do I know which is which? Also we can get to the idle stuff later but you said "black anodized heat sinks don't get scratched" your talking about the black plate that goes on top of them correct? And also what do you suggest on the thermal paste?
If you are referring to which is the other rear (left) channel then it's the one with the Q1xx (Q118 & Q119). I placed a star directly above Q217. As for thermal compound you might have to buy the stuff available for PC (computers) as they are available in small quantities and available in most electronic stores such as Fry's or RadioShack (if you can find one, lol). Or you could order some in larger amounts for a bit cheaper price, I use Dow Corning 340 and Wakefield 120 both are pretty affordable and come in different sizes as well.
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zx450 output fet right side.jpg (135.59 KiB) Viewed 12398 times
Thanks for the visual location I would have never looked under the black spacer lol. So by using the meter all of those predrivers and drivers are matching in numbers on all the other channels so I'm sure they are 100% good I'm going to order the new output transistors tonight. I will follow up once I received them I might go with fast shipping as I'm ready to get back on the road with some real tunes its just not the same driving without my PG
Okay I've install the new output transistors ready for the next steps not sure how to test the idle and ready to learn on this please school me on it! Also ready to the adjust the bias for the new outputs.. I cant thank you for all you have done it has been awesome feeling to be able to learn all this!!!! I installed the new transistors (which I read to do solder after the heat sinks have been re-installed then fitted to solder to the back of the board to make sure it fits to the board perfectly) trickyricky I heard your in tx..? I'm in AZ
You will see small yellow trim pots about in the middle section of the pcb, each channel has one. For the two channels you replace the outputs for you will want to turn both of them completely counterclockwise (just for these two channels, take a picture of its current position as you will find out it may be in near the same position once you finished). If you have a resistor use it (any value and wattage should be higher if you use low resistance) to charge up the filter caps in the primary side (the caps you should have replaced as they are known to leak), this will prevent a spark and possibly blowing up a fuse in your meter as you will be using it here in current mode in the next step. Use the DC current mode on your meter and place it inline with the B+ cable, then apply power to the remote terminal. Keep an eye on the current draw it shouldn't exceed 2amps. If amplifier is on without cycling on and off, then let it warm up for a good 10-20 minutes while observing the idle current. Once you have allowed the amplifier to warm up then take note of idle current, slowly rotate one trimmer pot at a time clockwise while observing the idle current. You'll notice the idle current increase slowly and once you get near half/middle point of pot you should stop and make sure idle current is not increasing, should be steady as soon as you stop rotating the pot. If it does continues to increase you need to IMMEDIATELY turn the pot just a hair back until the idle current is stable. You'll notice the idle current increase by about 300ma/0.3a per channel, for example if you start with 1.2a then you will end up approx 1.8a.
Do the same for the next channel, while keeping an eye on the idle current. After you set both pots you can then leave it on for another 30 minutes and make sure the idle current doesn't drift and remains constant. If all is good, you can now check for dc offset by setting your meter in DC (after removing it from the B+ of course) and check the DC voltage for each channel, should be less than 30mv/0.030v. If you pass all these quick tests/procedures then turn it off and hook up some speakers and rca's (as well as a 10amp-15amp fuse) and enjoy.
Yes I am in Tx.
Great soldering procedure, that's how I do it. I don't solder the middle/center pin as that is attached to the heat sink of the device and if the aluminium heat sink is attached it will draw heat from the center pin/leg and could possible cause a cold solder joint. So once I remove the anodized aluminium heat sink I then solder the middle pins of the devices. Am glad you did it this way as it could cause serious problems had you done it differently without the sinks.
I had this amp repaired over 10 years ago (Licensed Dealer) shipped it and after a lot money to fix it due to brother borrowing it and had installed the power wire between the car door and frame it pinched the wire and burned up top right side. Other than that only other issue I have had was RCA plugged seems loose for front side I would loose sound on bottom RCA and would need to move it a little to work again.
I'm going to order the next four capacitors under the crossover/RCA board but I'm running out of steps trickyricky... Please help!!!! I thought they looked bad and after removal they seem ok but will still order new ones since they are out. I have seem other post on ordering bigger ones what do you guys think? here's the replacement link 
