My new Tarantula

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shaheen
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Post by shaheen »

Hey There

Yeah , I did the repair work on a da-vinci , if it's an earlier board then it has a outboard transofrmer for the neon's , there is a guy on ebay who has them in stock .

I used LED Strips connected to a remote output on the board. If you want to keep it original then go with the neon tubes, if you want it to work without too much of a fuss and the worry of broken tubes, then go for the LED strips.

The Fans come on only when the amp is pushed really hard, if you open the top , you can disconnect the neon tubes and see of that does away with the whine. if it does then ur tubes are poked. While the top case is open , look at the fans when you drive the amp , they are controlled by a chip on the board with a temp sensor. Turn the gains up on the BLT you should see the fans start to move.
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Thumper88
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Post by Thumper88 »

Jacampb2 wrote:The next SS amp I really want-- the LE "Human Reign", not the plain jane one...
Would love to have one as well...pretty much the most unique amp I've ever seen...visually.
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Jacampb2
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Post by Jacampb2 »

Well, I bought another one-- really got to stop with these, they are a lot bigger than my pg amps and I'm going to run out of space.

Supposedly this one is in unknown condition, so I am assuming it is blown. Going to get time to work on them eventually-- I will keep you all posted.

later,
Jason
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M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Jacampb2
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Post by Jacampb2 »

So, I started on the most recent monoblock last night. It has some problems, biggest of which is some hack was inside it and left it in pretty bad cobbled up condition. When I first put power to it, it seems to power up normally, amp muted, power led on, then the power led goes out and status led lights, wash, rinse, repeat. Every cycle the current draw jumps to about 15 amps, so we've got a shorted or leaky transistor somewhere. The outputs seem to measure about normal in circuit, but the power supply fets do not, a couple of the ps fet banks look like they have at least one laker in the mix. First thing I did was solder everything. All of the fets and outputs have been screwed with, and they must have had a $2 radio shack soldering iron because every joint that was messed with was cold, cracked, our screwed in some way!

Put power to it again and now it never even tries to un-mute the amp, as soon as the pwm comes up it goes high current draw, so, I've got to start desoldering power supply fets until I find all the leakers. Hopefully I'll have the power supply fixed today and see what else there is that is wrong with it...

**edit** for a couple of pics, had to clean the board, it seems it had a cap explode some time ago, either that or the po stored it in a bucket of oil... It was a serious wreck, you can also see all of the cold solder joints in these pics before I fixed them.
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M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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marko
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Post by marko »

that's the problem with this beast, so many fets to go through!
Ti1 headunit (unique)
Outlaw in crate.
2x original shrouded ms2250's.
Route 66 in box + custom m100 to match.
Roadster 66 in flight case
Octane LE in box.
Reactor #186 in flight case.
Reactor EQ232
Ti400.2 AL
AX204A + EQ232 + ZPX2 + TBA set
ZCS6 component set
Tantrum+Titanium bass cubes
Ti12d Elite sub
DD5 + DD10 + 6 Ti blocks!
Jerome
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Post by Jerome »

i also own a tanratula 2kw monoblock. the only one here in France... it is the one with the 3d tarantula on it. Near mint condition.... :D :D
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Jacampb2
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Post by Jacampb2 »

Sweet! They are really awesome amps... when they work that is. I think that these are the the biggest A/B amps I have ever seen in person.

I spent the last 6 hours or so working on this bitch. I found the leaking fet. I pulled them all and then checked the whole pile. One bad transistor out of 28, and the really cool thing, it was a sub. The only Fet in the whole mess that is the wrong part and of course it popped. More reason stupid people should not be allowed to own/repair expensive amps!

So, the rails come up good and are stable, I only have 2 pairs of fets in it right now for testing, if they start popping like pop corn I don't want to have to replace all of them. Anyhow, powered it up, and no real high current draw, but it is still not right. There is some cyclic current draw for some reason. it idles around 5 amps then pulls 7-10 and back to 5. It happens fairly quickly, I would say at least one cycle per second, maybe 2. So, it as like something is switching on and off and drawing excess current. It is not enough to even cause the 4 power supply fets I have in there to sweat. They stay nice and cool, even with out the sink.

So, I go through and pull all 32 output transistors. I checked them all as I went and they all tested good (that's good news, they get expensive fast). So, I am still stuck, powered up with no outputs in place it behaves the same as it did with them. I'm thinking that gremlin is still going to be in the amplifier section, my guess is that the pulsing current draw I am seeing is the amplifier being enabled (un muted) and something in the amplifier stages drawing the above average current, the amp mutes again, then the cycle repeats.

So, it has been a pain in the butt to pull all these transistors, but in the end it will be worth it, I will be able to clean the crap off the board a lot better with the outputs and PS fets out of the way.

I will keep you's posted. Tomorrow is my last day for working on it before I go back to work. I'll try to make some actual progress :)

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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marko
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Post by marko »

fun fun fun Jason! good luck with this one, i'm usually stuck with this kinda thing myself. i do like to tinker but my knowledge has limits, i learn a little more with every amp i play with 8) i've been trying to get my ref1000s to work on both channels for ever but something is just not right :evil: may end up replacing the whole board one day :lol:
Ti1 headunit (unique)
Outlaw in crate.
2x original shrouded ms2250's.
Route 66 in box + custom m100 to match.
Roadster 66 in flight case
Octane LE in box.
Reactor #186 in flight case.
Reactor EQ232
Ti400.2 AL
AX204A + EQ232 + ZPX2 + TBA set
ZCS6 component set
Tantrum+Titanium bass cubes
Ti12d Elite sub
DD5 + DD10 + 6 Ti blocks!
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Jacampb2
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Post by Jacampb2 »

Yeah, lots of good fun. I have put another 8 hours or so in this pig. It is still having random issues and I have as of yet not managed to get it to un-mute the power amp. I thought it was enabling before and that there was a short somewhere in the amplifier and that that was the reason I was seeing these weird PS issues. Further investigation showed it was never actually enabling the amp, and it is actually in the PS. I would have it up rails stable, then all the sudden the rail voltage would slowly fade away, come back, settle in a a lower or higher voltage. I was seriously pretty stumped by this. I replaced the op amp that manages the 3 variable power supply levels, and that didn't help.

Today I put the PS issues on the back burner while I worked on the issue with the power amp staying muted. I checked the enable circuit out, and it it looked like the protection jfets were holding it out. So, I start to pull the two p-channel protection jfets to check them out, and I find that in their place the PO has subbed MPSA56 BJT's. I wish I had caught this about 12 hours ago. A BJT and a FET are not interchangeable. These p-channel jfets are only found in 4 places in this amp-- 2 are in the amps protection circuit, and two are part of the PS level switching. Swapping out the protection ones for the wrong parts was not enough for our idiot hack, he swapped out the two in the PS feedback section as well. I don't have any of these jfets in stock to replace them, but I suspect I have just found the answer to both the PS hunting around, and the fact that the amp wont enable... I tried to order the jfets during the first round of parts as I know they are a problem area, but no one had them in stock. I finally found some, and ordered them along with new wet caps for this prick.

My assumption thus far is that amp went into protect at one point in time. These amps have a small design flaw in their protection circuit, there is no gate resistor for the two protection jfets. If they trip, there is a good chance it is going to short, and they will stay that way. So, we assume the PO pushed it into protection, PO replaced at least one PS fet (probably more) and fixed the obvious blown components. Then PO try's to power it and finds that it still is in protect. PO finds/hears/guesses that the protection jfets are shorted. He swaps them out with a BJT because he can't find the jfets-- or maybe he doesn't know there is any difference in function and capability... I buy the prick on ebay, and have to go through things component by component to find all the shit that he cobbled. I have no doubt that I still have more surprises in store for myself...

Good news is, both this one and the 800/5 I got the other day were both still USA models, I found the handcrafted in the USA stamped on both of them. Since I thought all of the plastic spider ones were china made, I was pleasantly surprised to find these were still from the USA. Also, although the control panel for this one does not have the illumination switch, the board is still drilled for it, just not populated. The main board was populated for the lighting, all except the two pin header for power, so that is good. When I get new tops, this one will light up just like the other. Also, the PIC in this one is still good, I swapped it into my other older Tarantula today and it ran it without a hitch.

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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stipud
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Post by stipud »

Wow... what some people consider "repairs"! :shock:

Good catch. I couldn't imagine having to track something like that down!
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Jacampb2
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Post by Jacampb2 »

I'm sure it was done with the best of intentions. I assume it was for troubleshooting and this was all the guy had on hand. I just hope that there aren't a lot of other mismatched surprises for me. There has to be at least 500 discrete components in these things, and to have to go through each does not feel like fun to me.

I started in on the 800/5 while I am waiting on parts for the big boy. The 800/5 was sold as broken, supposedly the seller purchased it at a local auction and it had a "repair tag" and he claims he never tested it. I got it here and opened it up and someone had pulled all the PS fet's and the spring clips that retain them were missing as well. There were some signs of catastrophic mosfet failure, but it looked like this tech had actually done a decent job, at least the board was not butchered when he/she removed all those fets, and they cleaned up behind themselves as well.

Anyhow, kind of sucks not having the old parts. Missing the clips is bad enough, they are about impossible to find, I am going to have to drill and tap the sink if SS doesn't have any available. Not having the fets and not having the schematics for this amp means I am guessing on PS fets, but I have a plethora in stock and they are all pretty common given a certain driver style.

I started with 4 fets in it, a pair for each transformer, it has a +/- 30V set of rails for the 4 channel section and +/-60V set of rails for the sub amp section. Both sets have their own torroid. They share one PWM driver though.

Powered it up and had the fets shoot through pretty much instantaneously. Shame on me for not checking the push/pull bjt drivers. I just assumed the last guy did it as he went to the trouble to pull all the fets... I had some shorted driver transistors. Got those fixed and measured the gave voltage with no fets in place. I had a good 5V for each PS fet gate which is correct, thought I was good then, popped 4 more fets in, and powered it up and bang insta-short again. I went and pulled all the output BJT's, they all tested good in circuit, but at this point I was thinking it had to be a big short to kill a fet before it even had a chance to get warm. None of the outputs checked bad out of circuit either... 4 more fets-- 4 more shorted fets... At this point it is getting expensive. On a guess I pulled and replaced the PWM IC, it seems the orriginal one was damaged in the meltdown, as the new one no longer instantly blows mosfets. I'm guessing that the old PWM driver was allowing shoot through on the mosfets (shoot through happens if both sides of the PS mosfets are on at the same time, it's a very bad scenario and dumps a lot of current though the fets)

Anyhow, new PWM and it fires up for about 3 seconds and then for some reason the it shuts down. This is something going on in the PWM circuit itself, not the amp shutting down due to protection. I don't currently have any PS fets in it, I am just messing with the PWM circuit. I can see the PWM drivers come up for a few seconds, and then the driver output fades to 0v and it quits. The PWM is still up and running, the I have a measurable clock frequency of 50Khz on the oscillator out line, and each of the driver lines is pulsing at 25Khz which is all normal, but the driver lines are at like 30mV instead of 5v. I am thinking it has something to do with the way this PWM is sourcing the drive current. The designers actually used the separate collector supply found on the control IC. I have never seen anything done with this except to tie it directly to B+, sometimes diode isolated... Anyhow, I am still tracking down what they did to supply this pin.

I wrote into SS tonight to ask if I could have a copy of the schematics for this amp. That should help immensely. If anyone happens to have the Tarantula 800/5 schematics available and would like to hook me up, it would be appreciated!

Thanks,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Jacampb2
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Post by Jacampb2 »

Oh, and something I forgot to mention earlier. I said at one point that I may machine new tops out of aluminum for the monoblock tarantulas. I have been pricing 1/4" aluminum sheet in the quantity I will need and I'm thinking it would be more expensive than making them out of steel and having them plated.

With the procurement of the 800/5 which also has the plastic spider, I had a new thought. I am considering trying to source another plastic spider top-- I have already asked soundstream if they have any left, and my thoughts are pull the plastic spiders. With the spiders out, there is just a circular cutout in the case the same size as the logo. My thought is to engrave the tarantula logo in plexi and flush mount it in the existing round cutout. This means I can make all three amps match (the 800/5 would need a lot of redesign to have a case like the old monoblocks even thought they appear similar on the surface) and I think my 3d engraved spiders with side lighting would look pretty bad ass.

Tell me you thoughts! Obviously I have to get them all working or it is a moot point, but I think I am on track to get them back up and running.

Late,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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stipud
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Post by stipud »

Hmm sounds like someone may have been using your 800/5 as a parts amp. I couldn't imagine the hell of trying to get that thing working! Of course if it was anyone but you I would be skeptical if it could be repaired, but I am sure you will surprise me yet again!

Very stoked to see what you come up with with plexi. I never liked how the original amps were wide open for stray debris, but the plastic spiders are super cheesy, so your method should offer the best of both worlds!
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Jacampb2
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Post by Jacampb2 »

stipud wrote: I would be skeptical if it could be repaired, but I am sure you will surprise me yet again!
Consider yourself surprised, I got it up and running today. I still don't have any word from SS on if I can have the prints or not, but hopefully they will still hook me up. I have it kind of cobbled right now to get it up and running.

After a bunch of false starts and checking stuff around the PWM IC and finding nothing I checked out the feedback levels to the PWM. The inverting input was at 2.47V but the non inverting input was at 4.8Vdc or so.
I haven't yet figured out how they are doing their PS regulation, that is the main reason I still need the prints. IIRC it should have approximately one half of the reference voltage (Vref is 5V) at both the inverting and non inverting inputs for the PWM to run at 49% duty cycle which equates to 100% output, or the highest voltage that the supply is capable of making.

So, something is putting the feedback out of range. Instead of fishing around with out the schematics I decided to try a down and dirty little trick. I removed a resistor that was inline immediately prior to the non inverting input, leaving that input open. I then made a little voltage divider from a pair of 10K resistors. Center leg of the divider to the non inverting input, one leg of one of the resistors to the Vref pin, the other leg of the other resistor to ground and now we have an instant 2.5V on the non inverting input.

I'm pleased to say that it fired right up after that, however, I have effectively bypassed any voltage controlled current regulation that the amp had. I did spend a while testing it out, all five channels play and it actually sounds quite good!

Thanks for the vote of confidence though! If I hear back that SS has more of the monoblock tops then it is a done deal, I am going to make all three match with plexi inserts!

PS... My 4yr old daughter wants a "mad face" in here :D :twisted:

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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stipud
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Post by stipud »

I dunno how you do it man... :clap:

Mad face? Well there's :x :evil: :snooty: :idiot:
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Jacampb2
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Post by Jacampb2 »

Oh, the mad face was the twisted evil face. I was just explaining why it was there :D

Anyhow, more good news, I think I have the other big monoblock working now as well. I got the tracking number for my last parts order yesterday and it looks like it is going to be more than a week before they arrive, evidently UPS is getting behind with the holidays...

With the other amp up and running, I decided to put the output BJT's and rebuild the PS on the new tarantula. This is really a lot of work, 32 output transistors and 28 fets-- I only pulled them all to check them and they all checked out good except for that one subbed in fet, but we replaced that. I am pretty sure that someone somewhere along the line subbed the PS FETs once before. I have a couple of different prints for different revisions of this amp and they all list STP80NF06 PS fets. That is a 55V 80A fet, this amp had IRF3205's which are 55V 98A fets. All things equal I prefer to use the IRF parts anyhow because I have had some phenomenal luck with their stuff surviving where no one else's does...

So, no new parts before I go back to work, but I had some SOT-23 SMD style p-channel JFETs that should have been a decent cross for the old missing parts. The problem is they are SOT-23-- damn that is tiny! Anyhow, with the parts a week out, I decided to make do with what I have. I cut some tiny little PCB's and attached some short leads to it. Soldered on the little SMD JFETs and the rest was plug and play. You can see them in the first picture bellow, they are the little war of the worlds looking critters, I had to keep the leads long so I didn't accidentally de-solder them from the little boards as I made.

Image

Then, when I powered it up again for the first time with the proper JFETs in it I almost had this cap in the picture bellow explode in my face! That was scary!!! You can see I pulled most of the caps. I was actually looking for the source of all the crap on the board. None of these rail caps appeared to be leaking, but although they were the factory caps, they were not really the right part. The board is designed for snap in caps for the rail caps. My other Tarantula has snap in caps in there, but the photos on ampguts show other tarantulas with the same leaded caps in those places. Problem is, the snap in lead spacing is 10mm and the leaded caps are 7.5mm lead spacing, so they had to bend the leads to fit, none of the caps sat tight to the board, and it just looked like crap. I have already ordered new caps, so this isn't that big of a deal, but I thought it would be cool to show a picture, I had this thing as tight to the board as it could get with the bent leads. You can see in the pic where it lifted a good half inch off the board. It also made some terrible sounds that had me hitting the deck :D

Image

And here are just a couple of over all pics of the amp. It is never going to be a beauty queen, there has just been to much work done on it and the board is starting to show the abuse.

The good news is, it seems to power up normally now. I haven't actually tested it for audio output, but the power up sequence now behaves just like my other one, the amp un mutes, and status lights are no longer doing random things. Tomorrow I should have time to check and see if it actually has audio output, but I have no reason to expect that it wont.

Image

Image

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Kurt Wild
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Post by Kurt Wild »

Fantastic amps! But my humble opinion is that some of these dinosaurs are just too powerful and complicated for their own good.

When you are swinging around kilowatts of power, something is going to burn sooner or later. And when it does, its reckoning day!

Imagine doing a cap replacement job on one of these babies! Or imagine that shit shorting out :-x
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Jacampb2
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Post by Jacampb2 »

I wont disagree that they are complicated, but being a high power amp does not necessarily mean that they will be more prone to failure. If they are designed correctly, then they should have the same reliability of a smaller amp.

There are a lot of pro audio amps that make far more power than just about anything we have available for mobile use and they are perfectly reliable.

From a tech's standpoint though, big amps are down right dangerous. I have a one big CA that has +/-110Vdc rails, that is potential for a 220Vdc shock if you happen to get a hold of both rails. That is enough to easily kill you. Most people don't even realize that an amp the size of the Ti600.2 w/ it's ~ +/- 50Vdc rails has the potential to be dangerous, if not deadly...

My favorite part is figuring out the puzzle. I have more amps than I will ever be able to use in a life time at this point, and I think pretty much all of them were bought blown and are now fixed.

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Jacampb2
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Post by Jacampb2 »

Sound check this AM, and the second monoblock is indeed alive! Now it is just a matter of swapping out those JFETs for the ones on the way, and replacing all the caps and we are in business.

Hopefully SS gets back with me soon on if there are more lids available. I am looking forward to working a little magic and making these really bad ass.

I'm pretty :D geeked :D that all three are up and running now! Hopefully my luck continues-- I have three PG amps in my stash that I bought a few months back and haven't even popped the lids yet!

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
Virtue
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Post by Virtue »

With those amps, if you have any problems with 'no' sound or weird things happening after you fix the power board, replace the turn pots on the daughter board. I have 2 of those amps and I had to replace them... They didn't look bad, but, they failed internally. They are 10k 20k 50k and a dual 20k pots. I am still looking for a place that sells them... If you know of a place that sells those pots, let me know...

You have the best style which is version 1. I have a version 1, which you have and I also have version 2 which has the raised spider logo. I also found a design flaw with the version 2. In version 1, the fans on either side, suck air from the sides and pushes the air across the heat sinks towards the center of the amp, exiting through the cut out spider logo. Well, the noodle heads over seas messed up version 2. They first made the side vent slots half the size as compared to version 1, but, they didn't take into effect how the hot air exits the amp. There is no logo cut out and they didn't change the fan direction around to make it a push/pull design with the air. So, the amp gets absolutely no cool air and it just recirculates the hot air inside because the hot air can't escape! So, they cook! Nice eh!
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Jacampb2
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Post by Jacampb2 »

I have both styles too. My V2 was made in the USA however, so I can't blame over seas engineers. I noticed the smaller slots in the case as well and wondered about how well it was going to cool. I will take care of it before I run it.

Update on this though: This monoblock is not working again. I got my new caps and installed them all, put power to it again and it's up to the same old shit. The power supply is not coming up. The negative rail comes up to -30Vdc or so, the positive rail to like 11.5Vdc, that is a weird imbalance! I tracked part of the issue down to the PWM feedback, I bypassed the protection and feedback and got the PS to come up to +60Vdc and -65Vdc, rails are still to far apart and I am no further ahead on why the protection is holding it out again.

I did some more testing and found that the +/- 17.4Vdc supply is down. the negative rail of the supply has no output at all, the positive rail has anywhere from 12-17.4Vdc, it is floating around. Looks like it is moving around due to the over current protection built into this low voltage supply. It is a Zener based supply with a transistor amplifying the zener output current and another transistor to fold back the output if the current draw goes to high. The low voltage supply is powered from the amplifiers main set of rails. I think that I have a high current draw somewhere on the positive low voltage rail and that is why the +65Vdc rail is slumping so far.

I am not sure why the -17.4V supply is not there at all, in fact, it looks like the zener is not even seeing the -65Vdc from the main supply. I am guessing that maybe there is a bad trace or a bad via somewhere between the -65V rail and the zener for the -17.4V supply. I ran a external jumper and can get the zener part of the regulator to work, but there is still no output after the current amplifier transistor (yup, replaced it even though it checked good). With my jump in place, I am actually seeing up to +8Vdc on the -17.4Vdc rail. I am not entirely sure what to make of this. I'm thinking if I find what is loading the heck out of the +17V rail I might eliminate the issue.

There are very few components that use the low voltage supply in this amp. From the schematics it looks like two Jfet op amps use both rails of this supply, and the amplifier enable circuit uses the -17.4Vdc rail. I do not currently have the control daughter board installed which has some more op amps using the +/-17.4Vdc supply, so they can be ruled out as the problem areas. I already had replaced one of the op amps on the main board while troubleshooting early on, so I doubt it's the problem. I removed the other to see what the supply would do and it is still no go. I plan to remove that other op amp soon, maybe it is shelled for some reason, I'll pull it and do more testing...

Wish me luck!

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Post by The Golden One »

i wonder if it could be a bad diode causing current to leak back onto the 17v rail and loading it up with back current? :hmm:
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Jacampb2
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Post by Jacampb2 »

Well, it is fixed again, hopefully permanently!

Turned out to be relatively simple. I started by lifting the current sense resistors for the from the +/- 17v supply, this basically isolates the small supply from any load. I measured between the TP for the 17V supply and it reads lie a dead short across the rails. I try firing it up with the 17V supply isolated from the rest of the amp and it is still not right, this time I have like -4V on the negative rail and iirc +12V on the positive rail. I pulled both of the over current protection bjt's and I found one of them was shorted again. I checked the PS output again with the over current protection transistors out of circuit. Positive rail is now right, negative rail is still around -4Vdc.

Hmmm, at this point it almost has to be the zener diode for the negative rail. I just replaced those a day or two ago even though they tested good-- I have I think a bag of 150 of these zeners, and either I got one wrong zener in the batch or the other problems partially screwed it up. This one definitely tested good as a diode, but it was clamping at 4V not 18V it was supposed to. Weird, I know, and it did not help to have this along with all the other issues!

So, in tracking all this down, I found that the trace from the emitter of the neg rails darlington BJT to the current protection transistor was reading exceptionally high resistance. Visually it was fine, but it was nearly an open circuit. I soldered in a jumper to fix the trace.

Then, we had the known problem of the bad trace from the main negative PS rail to the zener in the 17V supply. I tracked that on the bottom of the board and it is good up to the rail capacitor bank where there is a via from the bottom of the board to the top layer, the via is under a cap, and I have to assume there is a trace on the other side that ties to one of the rail caps. Either this via is bad, or I didn't notice a fucked up a trace when I swapped the caps. I could have pulled all the caps on that side until I found the problem area, but I didn't want to abuse the board any more sinking that much heat into it to pull the big caps again. I corrected this issue with a 16awg jumper soldered on the back side of the board.

And for the dead short? That was the other op amp I mentioned was still left on the board. I pulled it out and the short went away. I can't see any good reason why it failed, but I suspect that what caused it was the fact that the 17V supply was not getting power on the negative rail when I first tested it after swapping caps. I'm guessing that destroyed that op amp, it shorted rail to rail and then that positive rail back fed the rest of the negative 17v supply and caused all the other failures. With any luck it is done for good now.

I put it all back together anyhow, here's hopping it's fixed for good!

and of course, the pics:

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Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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Re: My new Tarantula

Post by Frog4Life.com »

Was anyone ever able to get a hold of a schematic for the TA 2000?
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Jacampb2
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Re: My new Tarantula

Post by Jacampb2 »

When I was working on mine the company that bought SS sent me the prints for a few different revisions. I may still have them, but I am at work ATM and have no access. You might post up on DIYaudio.com in the car audio section, some of the people there might have them on hand.

**edit** If you end up not being able to get the amp running, I may be interested in purchasing it :)

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
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