strauss SVCL30 AMP faults?

irext · 29th September 2012, 09:54 AM

Has anyone had any experience with this amp? I am currently repairing one for a friend and it appears to have some unexplainable faults. Initially I found one of the 6BQ5 output pentodes to have a grid to screen grid short and a shorted plate protection diode. I replaced all 4 output tubes and the diode but subseqent testing showed it to have high levels of mains hum and not particularly clean output. I then found one of the diodes in the high voltage rectifier bridge to be missing. It looked as if it had never been installed on the pcb! The solder pads were totally clean with no sign of flux. Fitting a 1N4007 diode reduced the hum and increased the high voltage rail to just over 400V which is what I would expect. How could the amp have passed QC in the first place? It,s a pig of a thing to work on. You have to remove all the pot and socket nuts and drill out some rivets to get it apart. It then sits precariously on a bench like a bunch of grapes. Not designed to be worked on at all. It is of Chinese origin so I guess this type of construction is to be expected unfortunately. Has anyone else had the misfortune to work on one of these?

mastersweep · 2nd December 2012, 03:05 AM

Hi
I was given one this week end to have a look at
I appears that the toroidal transformer keeps blowing the fuse.
The only markings on the transformer are input voltage noting else
there are no output voltages
Does the transformer in your amp have any labels denoting output voltages
If you have measured the said output voltages would you be able to tell me so I can organize a replacement.
I agree with you the amps are a pig of a thing to work on
Cheers

29th September 2012, 09:54 AM	#1
irext diyAudio Member Join Date: Jul 2011 Location: Melbourne	strauss SVCL30 AMP faults? Has anyone had any experience with this amp? I am currently repairing one for a friend and it appears to have some unexplainable faults. Initially I found one of the 6BQ5 output pentodes to have a grid to screen grid short and a shorted plate protection diode. I replaced all 4 output tubes and the diode but subseqent testing showed it to have high levels of mains hum and not particularly clean output. I then found one of the diodes in the high voltage rectifier bridge to be missing. It looked as if it had never been installed on the pcb! The solder pads were totally clean with no sign of flux. Fitting a 1N4007 diode reduced the hum and increased the high voltage rail to just over 400V which is what I would expect. How could the amp have passed QC in the first place? It,s a pig of a thing to work on. You have to remove all the pot and socket nuts and drill out some rivets to get it apart. It then sits precariously on a bench like a bunch of grapes. Not designed to be worked on at all. It is of Chinese origin so I guess this type of construction is to be expected unfortunately. Has anyone else had the misfortune to work on one of these?

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2nd December 2012, 03:05 AM	#2
mastersweep diyAudio Member Join Date: Apr 2012 Location: Adelaide	Hi I was given one this week end to have a look at I appears that the toroidal transformer keeps blowing the fuse. The only markings on the transformer are input voltage noting else there are no output voltages Does the transformer in your amp have any labels denoting output voltages If you have measured the said output voltages would you be able to tell me so I can organize a replacement. I agree with you the amps are a pig of a thing to work on Cheers