Problems with power supply from high-amp.de (for electrostatic phones)

Hi together,

I am currently building the "Transistoramp V4.0" amp designed by Andreas Rauenbuehler.

You can find the layout, partslist and circuit on the website high-amp.de

(scroll down on the left for English version)

Now my problem is that the power supply is not working correctly.

The cicruit has an integrated protection for each the +400V and -400V section.

Now the +400V section works fine, but the -400V section goes into

protected state after turning on most of the time - until now it did not for 2 times

and the outputs were stable at 400V.

Does anybody here have experience with this circuit or can help my anyway

to track down the mistake?

http://high-amp.de/html/reg_pws_v4_schematic.html

This is the circuit.

The problem is solved since yesterday anyway, I exchanged the diodes D507 and D407

with some other ones that are 500mW types (had 1200mW before).

No the supply works perfectly stable.

But I have the next problem already - connected one amp board and after 

about 5 or 10 seconds it gave a loud boom - now T07b and R59 are blown.

http://high-amp.de/html/trans_amp_v4_schematic.html

This thing is drivning me crazy, never had a build that gave me so much trouble.

concerning the "smaller" diodes:

The developer himself is using diodes of that type and I was told that

there are only 0,0001A flowing through it.

That part of the circuit is a protection circuit and not part of the

"real" power supply (see the explanation on the website for that,

I do not know enough to explain it to you)

concerning blown components:

- T07b - not T08b is broken

- D56 seems to be broken indeed

- caps are showing correct values,

but I can only measure 3nF across C54 - but I also get only 3nF across C53.

which should be 100nF (But I also only get those 3nF across the other caps of

that type (in the power supply for example) - Might be because my DMM is 

not very accourate.

I did not understand that completely (maybe because I'm no native Englisch-speaker).

1. "S/C" short and capacity?

2. RD?

3. R11b is ok

4. other transistors (apart from T07b) are all ok

5. "If not check voltage feed in." 

I don't understand that sentence

Here's the picture I promised:

http://www.bilder-hochladen.net/files/4bhv-59-6cdd-jpg-rc.html

There is another thing I did not mention yet:

While dismounting the board and the transistors from the heatsink

I recognized that the isloation pad on T07b was a little too short and

a small part of the bare metal was open to the heatsink. 

(Should not have had contact, though)

May that have caused the problem?

Here's also a picture of the entire amps interior:

http://bilder.hifi-forum.de/max/183387/transistoramp-v4-innereien_271891.jpg

The damaged board is the one on the right.

I'll check all supply voltages again.

I also desoldered C54 and measured it - it's ok.

I just can't measure it properly in the circuit.

Have to order a new one anyway since I can't get the old one back in.

Seems I was really lucky.

I'm about to get the parts to replace this week.

I'll post again.

Well, after producing another short circuit by accident the amp now finally lives!

I'm currently monitoring the offsets but everything is stable.

Seems I'll be testing with my Lambda Pros in an hour or so :-D

Unfortunately, I have not built it for myself ;-)

But I can keep it for testing for about 6 weeks before the real owner gets it.

I'm very curiuos if I'll hear some difference to my exstata.

http://www.cavalliaudio.com/diy/exstata/main.php?page=overview

There you can find everything about it.

I built the tube hybrid version.

It's kind of a "poor mans" electrostatic amp, and has been discussed a lot

here in the forum at the time. (Even more (and more critical) in other spaces)