Randall RG100G3 powerFET amp

[N_Cook]

"no name", not Hitachi ,2Sk1058 failed in low power practise use. Securing
screw to h/s was fine . Known problem of Randall using suspect devices?
probably 2006 PbF/RoHS labels

 

[Phil Allison]

"Nutcase Kook "

"no name", not Hitachi ,2Sk1058

** Only Hitachi or Renesas make them.

Sometimes logos are omitted from the packs.

failed in low power practise use.

** How the fuck would you know that ?

FFS - report customer stories as STORIES !!

What is the nature of the failure?

Why do you EDIT all the facts out of your bullshit posts.


.... Phil

 

[N_Cook]

More evidence of dodgey sourcing. The mounting hole is visibly off-centre
relative to the hole in the flange, displaced vertically.
Looking under x30 one of the 3 injection casting vent holes has this "ident"
impressed in the 1.3mm diameter recess
MALAYSIA
AG
8
also a presumed date code of 6F1 marked under the K1058 for th earchives,
but no maker name or logo
This was D-S short failure

 

[N_Cook]

Off centre hole is 0.3mm displaced vertically. No first rank manufacturer
would have that amount of engineering departure from the industry TOP3
dimensions

 

[Phil Allison]

"Nutcase Kook"

Off centre hole is 0.3mm displaced vertically. No first rank manufacturer
would have that amount of engineering departure from the industry TOP3
dimensions

** Think you at clutching at straws instead of getting the amp fixed.

That FET has been working fine in the amp for many years - so it is not
likely to be a fake or dud.


...... Phil

 

[N_Cook]

I could not read the device number on the only other transistor on the pa
board. Required my PTFE magic trick to read it. Will add a bit of heatsink
to this TO220 .
TR7 on overlay
marked
TRF820
TR 542P
7D
and 83 impressed in the casting vent hole plastic
again no logo or makers name
no data found in wwwland
"passing off " as IRF820 ?
its not a bipolar transistor, the T of TRF is about the only readable letter
without PTFE, so not an I.

 

[Phil Allison]

"Nutcase Kook"

I could not read the device number on the only other transistor on the pa
board. Required my PTFE magic trick to read it. Will add a bit of heatsink
to this TO220 .
TR7 on overlay
marked
TRF820
TR 542P
7D
and 83 impressed in the casting vent hole plastic
again no logo or makers name
no data found in wwwland
"passing off " as IRF820 ?
its not a bipolar transistor, the T of TRF is about the only readable
letter
without PTFE, so not an I.

** FFS - the full schematic is easy to find:

http://music-electronics-forum.com/t16660/

Click on the thumb size schem at the bottom of the first post.


..... Phil

 

[N_Cook]

Back working again replacing the TRF820 and 2SK1058 principally. I would not
have expected to see just 1Kohm separating the gate of an FET from the
anode of a valve.