Problems with µDimension 420.4

yellow5 · 24th August 2007, 03:20 PM

Hello,

i'am new here and my english ist not very good

i have a problem with my 4 Channel Amp µDimension 420.4.

I hear some distortion when i hear for example pianomusik and guitar (no e-guitar)
it's terrible

If i have radiorushes (no receipt) on the amp and set the Lowpass 200Hz, i hear
some scratches as with a dirty vinyl.

I tested already much.
- another HU
- another Car
- another Speaker

with a laboratory power pack is it the same.

Its definitely the amp.

which problems could be the cause?

I'am a electrician, but here i don't know more.

Please give me some Tip, thanks!

Greetings,
Martin

Perry Babin · 24th August 2007, 10:20 PM

I'm not familiar with that amp but if this is an amplifier that has the RCA shield tied directly to the center tap of the power transformer's secondary windings, an open trace between the shield and the center tap could cause the problem.

If the problem is not the same in all channels, the problem could be a dirty switch or potentiometer but it's likely you would have noticed this when moving the various controls.

yellow5 · 27th August 2007, 12:31 PM

Hello,

the shield go not to the center of the transformer.

The signal come from the RCA and goes directly with a shielded
cable to the operation amplifier.

Heres a picture:

The Potis are good.

Someone still another tip?

Greetings, Franz

yellow5 · 27th August 2007, 01:15 PM

I have found a discrepancy.

The rail for 2x -15V and 2x +15V have 4 condensers pro rail.
3 rails have 100µF an 1 rail have 220µF

perhaps come the problem because of different sieving?

i have after the operation ampflifiers with a amplifier and a
loudspeaker attached and i have hear no distortions.
distortions are only at the exit (loudspeaker connection) of the amplifier

PS: the amp is new, but no warranty -> exhibition piece
before nobodoy use ist

24th August 2007, 03:20 PM	#1
yellow5 diyAudio Member Join Date: Aug 2007	Problems with µDimension 420.4 Hello, i'am new here and my english ist not very good i have a problem with my 4 Channel Amp µDimension 420.4. I hear some distortion when i hear for example pianomusik and guitar (no e-guitar) it's terrible If i have radiorushes (no receipt) on the amp and set the Lowpass 200Hz, i hear some scratches as with a dirty vinyl. I tested already much. - another HU - another Car - another Speaker with a laboratory power pack is it the same. Its definitely the amp. which problems could be the cause? I'am a electrician, but here i don't know more. Please give me some Tip, thanks! Greetings, Martin

24th August 2007, 10:20 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I'm not familiar with that amp but if this is an amplifier that has the RCA shield tied directly to the center tap of the power transformer's secondary windings, an open trace between the shield and the center tap could cause the problem. If the problem is not the same in all channels, the problem could be a dirty switch or potentiometer but it's likely you would have noticed this when moving the various controls. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ar.com dimension question	Bobhof	Multi-Way	6	23rd April 2006 06:23 PM
PP OPT Core dimension	silurato	Tubes / Valves	4	28th April 2005 09:42 PM
anybody tried http://www.acoustic-dimension.com ?	dcg69	Parts	17	20th April 2005 07:41 PM
PMC XB2, MB2 vent dimension	gengis	Subwoofers	1	23rd March 2005 10:02 PM
Cut Out Dimension For 12" Pioneer	Tony.ca	Car Audio	0	27th February 2004 07:32 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

27th August 2007, 12:31 PM	#3
yellow5 diyAudio Member Join Date: Aug 2007	Hello, the shield go not to the center of the transformer. The signal come from the RCA and goes directly with a shielded cable to the operation amplifier. Heres a picture: The Potis are good. Someone still another tip? Greetings, Franz

27th August 2007, 01:15 PM	#4
yellow5 diyAudio Member Join Date: Aug 2007	I have found a discrepancy. The rail for 2x -15V and 2x +15V have 4 condensers pro rail. 3 rails have 100µF an 1 rail have 220µF perhaps come the problem because of different sieving? i have after the operation ampflifiers with a amplifier and a loudspeaker attached and i have hear no distortions. distortions are only at the exit (loudspeaker connection) of the amplifier PS: the amp is new, but no warranty -> exhibition piece before nobodoy use ist