Tantrum 1200.1 quit working.

vageta31 · Post by **vageta31** » Tue Jul 28, 2009 6:05 pm

Ok so I bought a brand new Tantrum 1200.1 in a box about a month ago. Warranty sticker was still intact and it did indeed look new. Has worked beautifully the entire month up until Saturday when it just went quiet. The blue led is on but the fan is not.

I've done some research and it seems the tri-chip is a common issue and wondering if there is a way I can pinpoint this. Wasn't sure if the fan died which overheated the amp (doesn't an amp of this caliber have a protection circuit?), or whatever other problem that happened also killed the fan. It's dead quiet, no crackling, popping or strange noises. The fan part is what gets me unless it's somehow tied into the tri-chip itself, or if the fan dying is what caused the amp to fail.

vageta31 · Post by **vageta31** » Tue Jul 28, 2009 6:26 pm

A little more info. Took my DMM out to the amp and the DC voltage across the outputs reads -12.0v. Power input is 13.8 which is about what my other amp that has a voltage display says.

I'm guessing the (-) in front of the 12v is not a good sign hehe. Though maybe this can help nail down if it's the tri-chip or something else. If it's anything else I may have it repaired. If not I guess I have a boat anchor.

Post by **Jacampb2** » Tue Jul 28, 2009 6:51 pm

12Vdc on the output is a bad, bad thing. You have something causeing the output mosfets to leak. Either the tripath chip shit the bed, or it is simply a shorted fet. I have seen the 1200.1's with just shorted FETs, so all might not be lost. They will typically draw quite high current in this scenario, and it very well could have power supply damage too. I had one a while back that had a blown out power supply due to a shorted Fet and it still would light the LED with power... Open it up and check it out, or send it back to PG to be serviced.

Later,
Jason

lopezi · Post by **lopezi** » Wed Jul 29, 2009 4:52 am

Jacampb2 wrote:12Vdc on the output is a bad, bad thing. You have something causeing the output mosfets to leak. Either the tripath chip shit the bed, or it is simply a shorted fet. I have seen the 1200.1's with just shorted FETs, so all might not be lost. They will typically draw quite high current in this scenario, and it very well could have power supply damage too. I had one a while back that had a blown out power supply due to a shorted Fet and it still would light the LED with power... Open it up and check it out, or send it back to PG to be serviced.

Later,
Jason

I'd concur with checking the output FETs first.
If you feel adventurous here's a link that'll describe a testing process for seeing if the FET is blown (requires taking the FETs out though).

I'm unsure about how to test a TriPath chip, I have an amp with a TriPath chip, as well, but haven't had the chance to dive into it but I'm hoping the problem is in the output FETs.

If the TriPath chip is bad, the chances of replacing it are kinda on the slim side, although 41Hz.com appears to have access to the chips somehow. I'm not sure how PG approaches fixing these amps if the TriPath chip is bad.

jessegrant1028 · Post by **jessegrant1028** » Wed Jul 29, 2009 12:01 pm

I was rummaging through my garage because I was cleaning it out and I cam across an old ZX600TI that fried some ten years ago..... so I pulled it apart to see what might be the problem. I found a burned hole in the bottom of the PCB and the heat transistor was melted so bad that the terminals werent even connected anymore. I put new FET's in all 8 spots, bypassed the heat transistor, fixed the burned spot of PCB on the back side of the amp and put it back together.

I now get all three power supply lights to light up. I get all red lights to light up but I only get 2v to the fan and the amp makes a sizzling noise when I hook it up. IT doesnt blow fuses so im thinking its frying something inside?

I saw the work you did to the power supply of your zxti and was wondering if you had any ideas on where I should look next. [/img]

Post by **Jacampb2** » Wed Jul 29, 2009 3:24 pm

Did you replace the gate resistors? Those resistors are fusible and will go open with no external sign that they smoked. The sizzling sound is probably your new mosfets fighting for their lives. If you have any open gate resistors, then they are probably already shot.

What kind of current is the amp pulling? The blown power supply is normally the end result of other damage. You may have a shorted BJT output, or other transistor in the power amp stage that is causing current draw high enough to smoke the supply.

Later,
Jason

jessegrant1028 · Post by **jessegrant1028** » Thu Jul 30, 2009 9:25 am

I tested all the resistors on the power supply side. they all measure within their tollerances.
would a fried BJT keep the fan from getting 12v? or do you think the power draw from higher in the amp stage would be robbing power from the fan?
The two transistors that are standing up in the last picture (they are labled sf302 and sf302a.... what are those and could those be the problem?) they look friend and the resistors to those are getting really hot really fast and thats where the sizzling noise is coming from.

Post by **Jacampb2** » Thu Jul 30, 2009 11:05 am

Those aren't transistors, they are diodes. You have to pull their center lead from the board to check them. DO NOT apply power with their center leads disconected. Just meter check them. Chances are they are okay. What was your idle current draw?

If a output is shorted, then yes, it can pull the whole supply down. The fans run straight from the remote switched 12V rail in the amp, IIRC there are two comparators which vary the speed of the fan based on temp and other conditions. How did you bypass the thermal resistor? IIRC the thermal resistor should be at ~80 ohms at room temp. You could try putting a 75-80 ohm resistor in it's place. That could be your fan problem. I think that you still have a shorted output though.

Later,
Jason

jessegrant1028 · Post by **jessegrant1028** » Thu Jul 30, 2009 1:42 pm

I dont have a multimeter that will read amps and I dont have a clamp on meter either. so I have no idea what its drawing.....

here's a thought though... do the diodes labled sf302 and sf302a need to be isolated from the FEts in the power supply on the heatsink? I seem to remember two rubber type isolators or something on the diodes that I didnt put back on... I think I just put arctic silver on em'

Tantrum 1200.1 quit working.

Tantrum 1200.1 quit working.

maybe you could help