Xtant 3300c Fitzed!

[ezamps]

Thanks to 1moreamp Cecil who came through for me last year(!) with a basically intact Xtant 3300c "parts" amplifier, I have successfully completed repairs on IT rather than fixing my old one. I may someday revisit the old one, but it's pretty gutted out.

I didn't bother starting any repairs on the Xtant until early last week. It had been quite a while since I've repaired an Xtant amplifier that I'd forgotten a few key things about them and I'd never taken the time to really look at the design. One interesting fact - there are no secondary filter capacitors for the "Third/Mono Channel". The voltage rails are +/-63V which exceeds the ratings on any of the onboard 2200uF 50V caps. Tracing this out revealed that Xtant didn't really want people to hit that mono channel too hard with too much current capability. I used to run my old (2 amps ago) 3300c with 1 ohm on that channel with zero problems. I guess the rails sagged enough that it never caused the amp any stress!

After looking over the amp for a bit, I think it's a decent "CYA" design. It's not phenomenal, though and lacks a true audiophile design intent. The thermal management of many components is downright atrocious, burning several components up around the EXTREMELY HOT regulator transistors. I used to think Xtant was one of the best, but I'm going to recant that statement. PG still trumps that (at least up to the ZPA series, which is the last I had contact with).

Oh, the problem? An open Zener diode in the +53V predriver supply - was getting -3.2V at the output terminals.

[ydnap]

Good job man. Great feeling of achievement with stuff like this

[ezamps]

Good job man. Great feeling of achievement with stuff like this

Thanks! It's a rush - still. Even after having done it professionally, it feels real good to have an "old player" back in the system. I can now spend some time installing it. I can have a real system again! I'll need a sig.

[ydnap]

hehe.

IIRC the first thing I ever fixed and got working again was an old Rotel record deck. the arm had snapped off and all the teeeeeny little wires to the head had ripped..

I got an arm off of an old player (garard) and fitted it to the rotel, wiring the head into the circuit in the rotel and adding a stanton S500 head and needle.

It worked perfeclty, I was so pleased with myself.. I was only 13 at the time hehe, lots of casualties of war since, but I generally tend to repair more than ends up in the trash now

[1moreamp]

Congrates on your repair. I have long since given up on even trying to bring Xtant amps back to life. Especially now that MTX Mitec owns them and wants Xtant to die a quick death of the buy the company to kill off the brand. No support whats so ever at all now...

Do you need anymore Xtant amps. I think I have a few more in storage, unclaimed. A 4180 in perfect working order, No case though, and maybe a 1001D that was here from before my time. The 1001 makes a sweet doorstop...

The 3300C you got from me was a workhorse of a amp though, as I remember, something like 600 watts RMS at the blink of an eye. their power supply are so harsh and dirty, that and the high rails passing thru reg pass elements with tiny little aluminum tabs for sinks, and epoxied to the device to
Just makes you look and wonder "what the hell was that engineer thinking". They remind me of what a amp looks like if you were tripping on acid and designing a car amp all at the same time Sorta fried so to speak, and they all look that way.
The bad solder from excessive heat on the pass element leads tell the rest of the story. along with the melted and color turn by heat caps.

Damnest design I ever saw, borderline everywhere, and excessive heat everywhere. So much for the great Xtant cooling tunnel design, shame they did not mount the really hot components to the sink DOH !!!:lol:

[ezamps]

Congrates on your repair. I have long since given up on even trying to bring Xtant amps back to life. Especially now that MTX Mitec owns them and wants Xtant to die a quick death of the buy the company to kill off the brand. No support whats so ever at all now...

Do you need anymore Xtant amps. I think I have a few more in storage, unclaimed. A 4180 in perfect working order, No case though, and maybe a 1001D that was here from before my time. The 1001 makes a sweet doorstop...

The 3300C you got from me was a workhorse of a amp though, as I remember, something like 600 watts RMS at the blink of an eye. their power supply are so harsh and dirty, that and the high rails passing thru reg pass elements with tiny little aluminum tabs for sinks, and epoxied to the device to
Just makes you look and wonder "what the hell was that engineer thinking". They remind me of what a amp looks like if you were tripping on acid and designing a car amp all at the same time Sorta fried so to speak, and they all look that way.
The bad solder from excessive heat on the pass element leads tell the rest of the story. along with the melted and color turn by heat caps.

Damnest design I ever saw, borderline everywhere, and excessive heat everywhere. So much for the great Xtant cooling tunnel design, shame they did not mount the really hot components to the sink DOH !!!:lol:

Yeah, I feel a bit sheepish for thinking it was a good design. It did sound very good, though, on my old system.

You have more of them, huh? I never did get a 1001d working - and I count it among the five amplifiers I couldn't figure out without a schematic. Of course, I nearly counted the M100 with those, but after several more years of experience, the M100 didn't look so complicated after all (and it works, too).

I don't think I need them - but if you absolutely MUST get rid of them, I'll consider it. It's a freakin' sickness.

[Agent-J]

hmm...
i'm sitting in a similar boat.. i have an old M100 i'm trying to restore... It has been through a few very untalented hands before... lots of tracks burnt off .. and a few leaky diodes. Does anyone have any kind of digram for this M100? its a beauty and i'd hate to have to toss it out. They sound so nice.
I've replaed all teh fets and the switcher is working nicely once i remove teh comparator IC CA3140, looks like all the pins to the chip sit at about 32V, which is quite strange.

J

[1moreamp]

hmm...
i'm sitting in a similar boat.. i have an old M100 i'm trying to restore... It has been through a few very untalented hands before... lots of tracks burnt off .. and a few leaky diodes. Does anyone have any kind of digram for this M100? its a beauty and i'd hate to have to toss it out. They sound so nice.
I've replaed all teh fets and the switcher is working nicely once i remove teh comparator IC CA3140, looks like all the pins to the chip sit at about 32V, which is quite strange.

J

Hi Agent J you should start a fresh post and I will try to help you on your M-100. Please upload a pic of the board. ...C

I am looking at my shop reference M-100 board and I see the 3140 your talking about, and it does get 48 volts feed to it so as to tell the power supply control chip that the raw and rail supply are correct and in balance. so I don't think your problem is there, but it might be pointing you in the right direction please check all the supply voltages.

You should have +&- 16 and +&- 46 to 48 and +&- 52 to 54 volts < innthat range
If all these are correct then tell me the idle current draw at 12 volts, and then we can move on....C

[nick-caper]

I had a few Xtant amps. I thought they were the best amps I ever heard. Although they were the A2002, A4004 and A6001. I still think they are some awesome amps. I never had problems with heat. Maybe these older models I had were better designs?
And why dont more people use Balanced inputs and regulated power supplies? Its a no brainer!

[lashlee]

I've got three in my current install in the car and one in the truck. I've had no problems out of them, besides the one bone headed moment I had!! I guess I may be one of the lucky ones!!