ZX-450

thedeal7235 · Post by **thedeal7235** » Sun Nov 02, 2008 10:54 am

ive owned this zx450 since '96, and when my nephew returned it 2 me, a year ago, it had no output, and was being lazy about sending it in 2 PG-now, with losing my J-O-B gotta save wherever I can, well Jason(jacampb2), Schooled me on what 2 look for, and how to try & fix it, well, as of today it appears to be a bad transistor, I snipped out the bad one, once again after Jason's knowledgable advice, Powered that puppy up, & IT NEVER ONCE WENT INTO protect/thermal-so, 2morrow i am going to go and get the new transistors, can't wait to hear this baby AGAIN- THIS IS WHY I LOVE THIS phorum, and maybe this isnt the right place to commend Jason, but i just wanted u guys to know, how much I appreciate it here-btw, here are some pics-

Post by **Wakeup** » Sun Nov 02, 2008 11:06 am

Nice! Good work! Thanks Jason for as always continuing to be a major asset to the forum!

thedeal7235 · Post by **thedeal7235** » Sun Nov 02, 2008 12:55 pm

Post by **Jacampb2** » Sun Nov 02, 2008 5:29 pm

Awe shucks dude, you're making me blush!

I am glad that I could help.

Let me know how things pan out getting your parts...

Later,
J

thedeal7235 · Post by **thedeal7235** » Sun Nov 02, 2008 5:54 pm

more pics up soon, just working on the caps now, transistors came out no problem

deathcloud · Post by **deathcloud** » Sun Nov 02, 2008 7:49 pm

dang man if only i had the balls to do what you guys are doing. would save me so much money instead of shipping it out to PG especially on my x200.4 still trying to save up money to send it out. nice work though man hope everything works out for you.

thedeal7235 · Post by **thedeal7235** » Sun Nov 02, 2008 8:47 pm

more pics, just got the caps out, what a bitch on the posi, negative was a sinch-

this was built in 1996, caps i think began to leak, only b/c i was working on 'em, however, donyt wanna mess with this again in 6 months

maka78 · Post by **maka78** » Mon Nov 03, 2008 7:05 am

Jason, dude, help me out... I'm trying to figure out what the hell's wrong with my X200.4... http://phoenixphorum.com/problem-x200-4-vt7570-25.html

Post by **Rold Gold** » Mon Nov 03, 2008 7:53 am

Make sure to clean that board....... Ya don't want any of the cap juice sitting there.

But I'll agree, I'd be alot better off if I was confident in the area of electronic's repair. I need to get my 5 M's serviced and it's lookin like $700 if I have PG do it. If they go to Cecil, it'll be more though cuz I'll want all the available upgrades.......

denim · Post by **denim** » Mon Nov 03, 2008 8:11 am

Nice work, and yeah for Jason!!

rolandk · Post by **rolandk** » Mon Nov 03, 2008 8:48 am

Nice job guys, make sure you install and tighten down the heatsink BEFORE you solder those transistors in.

thedeal7235 · Post by **thedeal7235** » Mon Nov 03, 2008 8:54 am

what do u mean, i have to solder in the transistors, then i can put the heat sinks back in, how, and why i dont get it?place the transitors in place, then screw the heatsink in(thermal grease too), then solder from underneath????

rolandk · Post by **rolandk** » Mon Nov 03, 2008 10:09 am

thedeal7235 wrote:place the transitors in place, then screw the heatsink in(thermal grease too), then solder from underneath????

Thats right. You want the transistors to be perfectly flat against the heatsink. If there is any air gap between them, the transistor will overheat very quickly.

thedeal7235 · Post by **thedeal7235** » Mon Nov 03, 2008 10:21 am

ok, thanks for looking heads-up; i tried to call there this am, and says ur closed? also, should i put the new transistors in first, or new caps( they arrive here on wednesday, or does that even matter?, also, illput thermal grease on all transistors again, heatsink fins(on underneath where they screw in ontop of ceremaic type pieces, screw all that down, yeah i guess that makes sense, screws will hold the leads in, and then snip out excess leads, and then solder them, makes alot of sense as i continue to think about this-

rolandk · Post by **rolandk** » Mon Nov 03, 2008 10:28 am

We are open today, maybe you called before 8:00am PST. Dosen't matter which order you put in the transistors and caps, just make sure the amp is all back together before you power it up. Good luck!

thedeal7235 · Post by **thedeal7235** » Mon Nov 03, 2008 10:36 am

yeah, i will and seriously thanks for the heads up on the heatsinks, now i realize the rate you guys charge is actually VERY FAIR!!! the hardest part, seriously, was getting the positive cap leads de-soldered, I spent about 3 hours going very slow, and steady

Post by **Jacampb2** » Mon Nov 03, 2008 5:07 pm

maka78 wrote:Jason, dude, help me out... I'm trying to figure out what the hell's wrong with my X200.4... http://phoenixphorum.com/problem-x200-4-vt7570-25.html

I am sorry, but I probably cannot help you. I read the thread, and it sucks, but I have virtually no experience with the xenon amps. The only one I have is a 400.1, I bought it for $10 and didn't even try to fix it, I have just been using it for spare parts. The 400.1 is an entirely different design then the 200.4.

The "white noise" you describe, if it sounds kind of like wind on a microphone, well, it can be a sign of many of different problems. Cold solder joints, leaky output transistors, bad bypass caps, and many other things, including lots of potential problems in the input and crossover section. The fact that it goes into protect leads me to believe it is more likely a problem toward the output end of the power amp, but that is just a guess. From what I understand, Sanken transistors like this amp uses for outputs, are normally very reliable. I have no idea how the protection scheme on these amps works though, It looks like the 400.1 I have has a PIC in it though, and if I had to guess, I would guess that both the protection and the Xe-load function are controlled by the micro. If that is indeed the case, then we would have to see the code on the chip to know how the protection works, PICs can be read protected, so it is unlikely that we will ever see the proprietary code, even if you pulled the micro and tried to read it.

I have said before, and will again here, I just mess with this stuff as a hobby. There are many more knowledgeable people out there, considering that you have a EE degree, you probably have me beat

If you decide you want to sell the broken one, I may be interested in buying it and seeing if I can find the problem, I would then be able to give you guys more info, but it would still be a bit of a stab in the dark.

You also might PM roland, or call someone from PG and see if they can point you in the right direction, it seems the first revision Xenons are riddled with problems, and they must have some service bulletins...

Good Luck,
Jason

maka78 · Post by **maka78** » Tue Nov 04, 2008 6:39 am

Thanks for looking at it dude... I might have an EE degree, but I think you def. got me beat on this stuff (I only learned theory in school, didn't actually go into the stuff physically). I can understand what you talking about, but that's about it, lol.

Anyway, thanks for your input. I can just go and start replacing parts from one 200.4 to the other (I have two, one that works fine) and see what works (yeah, old brute method way), but I might hold off on that before I break the one that's working too.

thedeal7235 · Post by **thedeal7235** » Tue Nov 04, 2008 9:24 am

u know how i found my problem? i used the dmm and checked the ohm load on each channel( unhooked ofcourse), AND THAST WHEN I TOLD JACAMPB2 MY FINDINGS, THE LEFT FRONT POSI, AND NEGI, were showing .512, all other channels were ol, innnnnnnnnnnnnnnnnnnfthe other chanel, so he told me how 2 check the output transistors, and i found the 1 transistor that was very low in resistance to all the others, sniped it out, powered up(very briefly as heatsinks were off, & the amp no longer switched constantly to ovl/thermal, as it had with no output, if it still would of done that, then i think jacampb2 said it would the power supply transistors? i got lucky, along with his help and guidance

thedeal7235 · Post by **thedeal7235** » Wed Nov 05, 2008 3:32 pm

ok, so the Transistors arrived this morning( they look identical to the oem motorola, w/out motorola logo, put new caps in( this board showed no signs of leaking, however, I figured this is from 96, so do it while ur here, and as u can see via the pics it fired up, and let me tell you, both my ti amps are comingout tonight, the zx, imho, is EVEN SHARPER in clarity @ low and high volumes, thinks jacampb2, can't believe i was able to do this-also the transistors came from newark, www.newark.com,

Post by **stipud** » Wed Nov 05, 2008 3:45 pm

Now you just gotta figure out how to set bias and you'll be a pro

thedeal7235 · Post by **thedeal7235** » Wed Nov 05, 2008 4:05 pm

hahah, what the hell is that?????????????????????????????????????????????

thedeal7235 · Post by **thedeal7235** » Thu Nov 06, 2008 11:00 pm

wait aminute, ru refering 2 the yellow pots/adjustment of such pots inside the amp? if so, i wont touch those, know they were originally set via the factory, so ill never touch'em, however i found cecil's post about distortion/dc offset-very interesting

Post by **stipud** » Fri Nov 07, 2008 7:41 am

Yep, if you can learn to properly set bias, your amp will sound amazing. Way over my head still, unfortunately

thedeal7235 · Post by **thedeal7235** » Fri Nov 07, 2008 9:04 am

cool, i understand; I would think it has to, obviously, do with the output, mayb kinda similiar to the bass cube secrets(adjustment on that put relating to db increase/decrease); but ifa person doesn't know, its probably always best to leave them alone-

ZX-450

ZX-450

more pics-under board