Aleph Ono Swichting Problems

[TheMyxin]

Since saturday i have problems to switch on my Aleph Ono.
The Correction from PQuadrat is ok (Connection between
D10 and D11 and the Cutting on the PCB. I have checked this
with my V/I-Meter). I have also checked the Z-Diodes in
with my VI-Meter on the Diodetests. When i switch on i can
see that the PCD-LEd (D?) switches short time but then goes
out quickly. I have measured that D11 in blocking direction is
ok when i have not connected the RElais-Outputs but with the
output i can read 0,9 V. I have changed the Diode which not
helps. I think that the MOSFET Q25 is damaged ?
R19 has now 1.5 Kohm in my case. Is it possible that the
swichting current on the unregulated 42,9 Volt is perhaps to much
for the MOSFET with a 120 VA torroid transformer ?
Thanks for help. This is my first big DIY-Project.
What about heatsinks for the MOSFETs ?

[Boban]

TheMyxin,
try posting the schematic with as much voltage readings as you can, similar to my post from the other day (http://diyaudio.com/forums/showthrea...threadid=13960) and someone will be able to help you.

Regards
Boban

[TheMyxin]

[QUOTE]Originally posted by Boban
[B]TheMyxin,
try posting the schematic with as much voltage readings as you can,

Ok due that the Led on the Power-PCB-Board dont switch on,
the supply Voltage failid complete because the Relay-Parts are directly behind the Diode-Bridges. It works as switching delay before it swichts on the main-ono boards. (i have got this information from PQuadrat). Thats why i think the MOSFETS
Q25 and/or Q26 are damaged. I have put a schema as jpeg-pic
in the attach

[Jens]

Did you measure Q25/Q26 if they are still okay, if not, do it first. Regarding the relay, it should switch the output only, it has nothing to do with the main voltages. If there is no short, you should be able to measure +/-30VDC. Leave Q25/Q26/relay out and check what is happen…

[stefanobilliani]

Try do measure the voltage at the drains of Q9 and Q23.

Use 3Watt resistors for R44 and R71.

[Jens]

It may helps, append you will find some measurements...

[TheMyxin]

Originally posted by Jens
It may helps, append you will find some measurements...

Today i have time to check that problem.
I habe just exchanged the Resistor R77
which has 0,25W agains 0,6W type.
Know all seem to be ok. I have also swichted the PCB 7 times without any
problems. The Ono-Boards were not connected. I have put a Picture with the
voltage measurement results.

The Resitors R43/43A/44/70/70A/71
are 2W Metalloxid. I think this is enough
and i dont need 3W Resistors ?

[stefanobilliani]

Originally posted by TheMyxin


The Resitors R43/43A/44/70/70A/71
are 2W Metalloxid. I think this is enough
and i dont need 3W Resistors ?

2W are enough. I, originally find some problem in the filtering with 1/4 watt res. and bigger capacitor (10000 u ) and the ono did not turn on . Then I put 3 watt and realize that 1/4 w was too small.

[TheMyxin]

[QUOTE]Originally posted by TheMyxin
[B]

Today i have made some measurements and it seems to
be ok. I observed that the Voltage regulator Q23/Q9 MOSFET
become very hot after few minutes (just subjective measurements
with my fingertip). The voltage is ok on the source/drain and
gate. But i think to put some heatsink on the MosFets ?
The MOSFETs 9110er become also hot after some time. I have put
there some small IC-Heatsink for 6-8 Pin) with heatconducting
self adhesive tape). But it become not so much hot as the
voltage regulator MOSFETs.
Hase somebody measured the temperature in Celsius on the surface of Q9/Q23 ?