quad 405-2

goodguys · 10th March 2011, 10:07 AM

Hello and thanks for taking the time to read this post.

I purchased a pair of quad boards from here :
DIY Stereo Audio Power Amplifier Assembled fr QUAD405 on eBay (end time 15-Mar-11 07:12:35 GMT)

1. Does anyone have experience of these, How do they compare against standard quad boards.

2. The first four luger-style connectors are identical to my quad boards: that is phono input, then speaker out, then -54volts, then +54 volts, unfortunatly there is a fifth luger connector labelled " gnd " which my quad boards do not have, i contacted the manufacturer who said it is the power ground, so i connected it to the smoothing capaitors of the power supply, when switching on i got massive distortion then both boards blew. Does anyone know where i went wrong.

Many thanks in advance. John.

Ouroboros · 10th March 2011, 11:06 AM

The original QUAD405 pcbs picked up the 0V supply via the heatsink. The case of the 405 is at 0V, and is connected to the centre 0V point of the two large PSU electrolytic cpacitors.
How were you connecting the new board to the front heatsink? From the pictures it looks as if it would need a totally different 'T' or 'L' aluminium extrusion. Was your insulation ok between the transistors and the aluminium heatsink bracket?

poynton · 10th March 2011, 11:27 AM

There are quite a few threads already about this.

Search for Quad 405 clone

As far as I can tell, they are clones of the original 405 not the 405-2.

Coming from China (via the UK?) the quality of the components may be suspect especially with regard to voltages and power handling.

Andy

.

Edit... This is probably in the wrong forum. Should be in Solid State not Chip Amp.

goodguys · 14th March 2011, 09:35 AM

Hi. Many thanks for the reply. I have put an attachment405-2.jpg on to this post hope it comes through ok. There is a green wire running between the two smoothing capacitors of the power supply this is where i connected the 5 luger connector to labelled " gnd "

10th March 2011, 10:07 AM	#1
goodguys diyAudio Member Join Date: Feb 2011	quad 405-2 Hello and thanks for taking the time to read this post. I purchased a pair of quad boards from here : DIY Stereo Audio Power Amplifier Assembled fr QUAD405 on eBay (end time 15-Mar-11 07:12:35 GMT) 1. Does anyone have experience of these, How do they compare against standard quad boards. 2. The first four luger-style connectors are identical to my quad boards: that is phono input, then speaker out, then -54volts, then +54 volts, unfortunatly there is a fifth luger connector labelled " gnd " which my quad boards do not have, i contacted the manufacturer who said it is the power ground, so i connected it to the smoothing capaitors of the power supply, when switching on i got massive distortion then both boards blew. Does anyone know where i went wrong. Many thanks in advance. John.

10th March 2011, 11:27 AM	#3
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	There are quite a few threads already about this. Search for *Quad 405 clone* As far as I can tell, they are clones of the original 405 not the 405-2. Coming from China (via the UK?) the quality of the components may be suspect especially with regard to voltages and power handling. Andy . Edit... This is probably in the wrong forum. Should be in Solid State not Chip Amp. __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

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10th March 2011, 11:06 AM	#2
Ouroboros diyAudio Member Join Date: Dec 2003 Location: Nottingham UK	The original QUAD405 pcbs picked up the 0V supply via the heatsink. The case of the 405 is at 0V, and is connected to the centre 0V point of the two large PSU electrolytic cpacitors. How were you connecting the new board to the front heatsink? From the pictures it looks as if it would need a totally different 'T' or 'L' aluminium extrusion. Was your insulation ok between the transistors and the aluminium heatsink bracket?

14th March 2011, 09:35 AM	#4
goodguys diyAudio Member Join Date: Feb 2011	Hi. Many thanks for the reply. I have put an attachment405-2.jpg on to this post hope it comes through ok. There is a green wire running between the two smoothing capacitors of the power supply this is where i connected the 5 luger connector to labelled " gnd "