I just spoke with Gordon, he didn't design the amp. My understanding is that it's an S & I design.

Interesting story, I have a clients MS2125TA on the bench right now. In addition to a mess of other issues, it to has the O/L LED lit all of the time even though protection isn't tripped and the poweramp is not muted. In this amp it turned out to be a bad LM339. It was leaking just enough to allow t...

I'm really sorry, I forgot about this. R47 may be responsible for the fact that the green LED is not lighting. It should not be causing the O/L led to light. The weird thing is that if the o/l led is lit, then the power amp should be in mute. The same output that drives the led should cause the prot...

I'd be interested in your blown ZPAs. Pm me if you want to discuss.

Thanks,
Jason

Sorry, I haven't been on here lately. I'm waiting at the vet for my dog at the moment, but I'll try to look into it when I get back to the shop.

Gordon designed it???

Were the voltages taken with or without the outputs in circuit? When you say speaker ground, do you mean the non inverting output for each channel, i.e. the terminal with no signal present that is connected to secondary/audio ground? I ask because the only one of the terminals marked (-) are actuall...

I personally don't care for how the PG xs and tantrum amps (basically the same amps in similar power levels) sound. They are still solid amps, and make great power, but the only one of those two lines I ever liked was the Tantrum 1200.1, and that amp isn't even remotely similar to the other tantrums.

The one in the picture is correct. I replied to your fb post, but the part numbers you posted there came up as a different style. I'm not sure now if my input got auto corrected, it what happened, but anyhow, I posted the part numbers there. You but then in single gang and just install as many as yo...

I can confirm that if A)remote goes high before the B+ or B) Remote and B+ go high together, that the thermal LED does indeed light on power-up. This is probably not a great way to power the amp, and the fact that it does this means that parts of the protection circuitry are having their power suppl...

I checked my 0.3 that I use as a reference amp on the bench the day after I replied last time. This amp is on a power supply and it's completely without power for 12+ hours before I fire up the shop in the mornings. I wouldn't swear to the caps being completely discharged, but I expect they are. I'l...

Any time the amp is in thermal or o/l, the poweramp is muted. Q4 on the differential amp daughter boards is the mute transistor. Basically the way the power supply control is set up is that you should never be able to have a green "power on" led at the same time as either thermal or o/l. I...

I miss forums as well. FB is just too many millenials asking the same stuff they should have searched. I wonder how long they and this one have left I asked Tom last year or maybe the year before if he was interested in my mirroring the phorum or selling the site to me. We had seen a few brief spor...

If the noise goes away with the crossover bypassed then it's possible that it is a faulty pot in the stack of pots. Did you try cycling the frequency control to see if the noise changes or goes away? If it is one of the 10 pots in the stack then you should hear some changes when you cycle it. If the...

For clarification, you are saying that while the audio system is running, there is a hum coming from the speakers which remains even with the engine switched off? First, definitely check to see if have the Panasonic caps in that amp. Many ZxTi amp had them, it's not likely your problem, but it's goi...

Power on sequence should be just o/l led when power is applied. Switched to green power led when the poweramp comes out of mute. Fans should stay on low speed throughout. Thermal should never light. And the amp should start in high voltage mode and only switch to high current when the rail switching...

I'm still on here every now and again. For some reason the phorum quit alerting me of private messages. I'm on Facebook more often as Scott mentioned. The PG classifieds group or my tech group. Feel free to pm me there and you will get a lot faster response. My audio tech group: https://www.facebook...

The output on the board is 12V, the actual neon transformer output is probably closer to 20kV, so don't hook to the actual wired that go to the tubes. Follow it back to the small black box and use the 12v wires that go into it. That said, I like the look of real neon far better than LEDs. The tubes ...

BTW, if the LEDs have failed, do not buy just random 3mm LEDs. You need to get LEDs with a Vf (forward voltage) of 1.2-1.4V. look at the datasheet before you buy. Most random LEDs in eBay or Amazon are not going to be characterized or come with a valid datasheet. You will be better if ordering from ...

It's getting pretty common for the current source LEDs to fail in these amps. The very first thing I'd do is check to be sure they haven't failed. After that, start going through the fusible resistors in that channel. The fusible resistors look a bit different than the regular counterparts. They als...

So paying $125 for that 20 fared new was a bad deal it sound leak. The 10 and 20 farad models used an array of very small supercaps to reach their rated capacity. Sadly, a lot of the caps leaked and it soaks into the board and many times shorts out the power and ground planes and starts a fire. The...

I repair nearly any car audio electronics, although I'd say my specialty is Phoenix gold. I can give you details and my email contact info if you'd like to drop me a pm. The zxti amps may need to have their power supply caps replaced. Most of the zxti amps still had the faulty Panasonic caps. Do not...

Here's a link to my general tech group on FB as well.

https://www.facebook.com/groups/149769529274064/

I found a screenshot for the final draft of my modified power supply card. The pdf attached in the last post may be more useful since the attached here has several deviations from the stock design including a switch to lock the amp in HV mode and buffers for the sg3525 to allow the amp to drive mode...

I hope these work, I'm on my phone and could only find the pdf for one of them, the other is a screenshot.

I'm also not sure I'd they are my final revisions, but I'll try to get them from my PC when I'm back to the shop.