Warning to potential AMP11-HV buyers

[Matthias]

Hello there,

I finished my AMP11-HV yesterday and it works flawless with 24V.
Today I tried 45 V and got no luck:
Fault pin of STA517B is active (low)!

This is the same behaviour some other builders the last weeks could see!
There must be some kind of fault in current STA517B batch or they are fake.

I'm currently investigating further on this and will get back to you when I have more information about this issue.

So far I can only recommend not buying an AMP11-HV at the moment. Is there anybody who built this AMP since 01/2011 with success at higher voltages?

Matthias

[Jan]

Hi,

Like I have written before, I will replace the chip if faulty. When did you buy yours?

Jan

[Matthias]

Hi,

Like I have written before, I will replace the chip if faulty. When did you buy yours?

Jan

Hi Jan,

that would be very nice of you!

I bought it few days ago, Order 8825 (15.03.2011).

You wanted to add my missing Truepath 220 nF output filter capacitators but forgot it - would be even nicer when you add them to my replacement STA517B :)

My investigation showed that FAULT begins to become active at about 39,7V with no hysteresis. I did not desolder Tristate/Powerdown pins, so I could not see those signals seperated.

Thank you very much, I would not have requested this from you (because it cannot be taken as your fault when you got faulty chips - you just sell nice amp kits and I dont think there is much profit for you)

Matthias

PS: I scanned a high res version of my pcb/sta517B:
http://matthias-larisch.de/datenablage/krimskrams/platine.jpg

[Jan]

For now, I have removed this kit from the web shop until this is sorted out.

[V-bro]

I have a couple of working AMP11-HV so if it helps to provide some data from the chip on it it's available!

[Matthias]

I have one problem: I will not be at my home / solder station until the end of april. So I cannot make further investigations or replace the chip. If this is okay, you can send me a new one and I will test it end of april. Maybe someone else with experience in electronics AND a "faulty" Amp11-HV with this behaviour can do something till then?

I checked a bit more with my scope but it really seems that the STA does all this "fault" stuff on its own - maybe someone should make a small test build just with sta, 2 capacitators and Vcc?

[Jan]

I have a photo from Mathias for the non-working batch, so one of the IC for some working batches would be good.

[Jan]

I checked a bit more with my scope but it really seems that the STA does all this "fault" stuff on its own - maybe someone should make a small test build just with sta, 2 capacitators and Vcc?
Yes, the fault pin is directly from the STA517B, via a driver transistor only. I may be able to test in the coming week but first, lets see what different batches look like. They usually have production dates / weeks etc and other printings that vary.

[Ascomar]

It could be useful to try with a variable power supply in order to know which is the Vcc limit.
My fault STA517B worked flawlessly at least up to 30 V and remained stuck in the Fault state at 45 V.
Considering that other pin to pin compatible products of the STAxxx family are guaranteed to work up to 40V (e.g. STA505, STA506, STA508) I would bet that the problem is around this value. Unfortunately I am not able to check this hypothesis as I don't own a suitable power supply.

[Matthias]

As I said I tested with a variable supply (I have 0-24 V supply and connected two ~~12V supplies in series so I could test about 35-45 V) and the shutdown/fault active point was at about 39,6-39,7V. I could adjust to a point where the "rest ripple" 50Hz from the 12V supplies lead to 50 Hz fault active/not active, so I think there is about no hysteresis. Measurements where taken with an oscilloscope and precision multimeter so I'm very sure about those values.
I measured directly at the fault output pin at STA517B. I also monitored all other Vcc/Vss/GND Pins at that chip, there were no flaws.

[quixfz]

here are mine:

http://upload.festzeit.ch/upload/zeug/41hz/sta517b.jpg

both worked fine with 30V, with around 120mA standby, dont remember exact value.
the left burned up after a 1-2 minutes trying around (the fault-led was on) with (possibly badly isolated) 2x 24V psus. when plugging the psus out of the wall, the amp would work for a short moment, when the voltage went down.
the right one imidiately gave a loud pop and the 4 pins were gone, tried with meanwell 48V psu.
again, both worked fine with 30V...

PS: hifimediy removed the T3 (same ic's as amp11) from the shop, because of some "noise issues", and it isn't back yet... maybe he knows something

[V-bro]

Maybe Jan should just divert to STA516B to avoid the confusion....

[Matthias]

So if I should test one new STA517B you should send it to me the next days, I'm at the amp & solder station from next Friday till Tuesday :) And as mentioned earlier, I'm still missing the 2 Truepath Output Filter Caps, 220 nF.

If you don't send me anything I can easily order that myself but that would be in a few months (or later) because I don't have much time and would make an order together with some nice parts for a planned high performance audio dsp that has to be designed first :)

[Fernando]

What are the values of R52 and R54 you have?
Measure and inspect them and see if it is all OK.
VPPSense is made for over/under voltage protection.

[longitude]

Unfortunately, I have the same problem with my STA516B chip.
I bought eight amp11-HV for my Linkwitz Orion speaker.
The preliminary test with 24 VDC SMPS are all O.K.
But after I connect them with 48 VDC power supply.
All eight STA516B chips fried!
Anyone get amp11-HV with STA516B and encounter the same situation?