Oh yes, just noticed them in the pics for the AU-6900 :stupid:
Fuse Resistors - The where's, why's and how's
- Thread starter skippy124
- Start date
Oh yes, just noticed them in the pics for the AU-6900 :stupid:
Karl vd Berg
Super Member
roger2
.
Just replaced the 150Ω fuse resistors R35/R36/R45/R46 in an AU-317 per post #4. All of these had drifted high, but I was surprised to see how far one of them had gone. I took readings with the resistors removed from the amp and this is what I found: 2.2kΩ, 2.6kΩ, 218Ω, and 80.7kΩ.
The channel that had the 80k resistor was showing no bias voltage regardless of the trim pot setting. After installing new 150Ω metal films I was able to easily set bias to correct value in both channels
Thanks skippy124 for the useful info and a great thread :thmbsp:
The channel that had the 80k resistor was showing no bias voltage regardless of the trim pot setting. After installing new 150Ω metal films I was able to easily set bias to correct value in both channels
Thanks skippy124 for the useful info and a great thread :thmbsp:
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Roger2 - did you get the two 68Ω - R17 & R18 on the Tone Board?
Here
http://www.audiokarma.org/forums/showpost.php?p=5507556&postcount=4
Here
http://www.audiokarma.org/forums/showpost.php?p=5507556&postcount=4
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Alienz
Super Member
How about the AU-3900?
Try here:
http://www.audiokarma.org/forums/showpost.php?p=5513455&postcount=16 (post #16 of this thread).
roger2
.
Thanks for the heads-up. But no, not yet. For now I just wanted to see if I could get this amp working, and it is. If/when I am able to go through the amp I will change those other two for sure.
Alienz
Super Member
Thanks John, looks like I need to investigate this to make sure. I replaced some resistors in mine after I put a cap in backwards. I was not aware of the existence of fusables at the time.
AU-555 Fuse Resistors
I have just read this thread for the first time,what a wonderful resource.
Could anyone please provide me with the values & locations for the fuse resistors on the AU-555.
I think that my amplifier needs replacements after reading what happens when they go out of spec.
Thank you in advance,
Regards,earleb.
I have just read this thread for the first time,what a wonderful resource.
Could anyone please provide me with the values & locations for the fuse resistors on the AU-555.
I think that my amplifier needs replacements after reading what happens when they go out of spec.
Thank you in advance,
Regards,earleb.
Welcome to the Exclusively Sansui forum earleb.
I don't think there are any fuse resistors in the AU-555, however this thread was started and is 'owned' by skippy124 (John). I am certain he has restored at least one AU-555, so he will very likely know for sure if there are any.
Please be patient and I am sure he will post here to confirm.
I don't think there are any fuse resistors in the AU-555, however this thread was started and is 'owned' by skippy124 (John). I am certain he has restored at least one AU-555, so he will very likely know for sure if there are any.
Please be patient and I am sure he will post here to confirm.
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Hi earleb, and as John said, welcome to the forum.
There are no fuse resistors in the AU-555, but there are some other components that can cause issues such as the 2SC458 transistors.
If you are having problems with your 555 then it would be best to start a thread on this, where you will get help.
Cheers
John
There are no fuse resistors in the AU-555, but there are some other components that can cause issues such as the 2SC458 transistors.
If you are having problems with your 555 then it would be best to start a thread on this, where you will get help.
Cheers
John
Hyperion & skippy124,Thank you for the welcome.
I am a non technical person and starting a new thread would be a waste of your time.
I have only owned the AU 555 for a short time.Only one previous owner and by the condition of the amp,inside and out must have been stored away for the last 40+ years.
I picked up an immaculate pair of Klipsch KG-4 in the past week and that is when I noticed the noise issue.
The amp seems to have too much gain when partnered with these speakers.
Today I thought I would try my Silk TVC with the Sansui power section only.
The outcome,hardly any noise at all.
I would have to put my ear next to the speaker to confirm that the amp is switched on.
The only mods that I have done is to replace all the capacitors,a mixture of high quality Nichicon,Elna & Panasonic.
A thank you to petemac on StereoNet for his help via PM's
So,while I love the AU 555 as an integrated amp I can live quite happily with using it as a power amp.
Best regards,Earle.
Hi Earle,
If you are having noise problems (hiss, crackles and/or pops), then it is highly likely being caused by the 2SC458 transistors in the preamp sections. These are known noise makers. If you have successfully done a recap, then you should be capable of replacing the transistors in the preamp sections with some guidance. Let us know if you would like to have a go at this.
Cheers
John
(PS - pete_mac on SNA is my son)
If you are having noise problems (hiss, crackles and/or pops), then it is highly likely being caused by the 2SC458 transistors in the preamp sections. These are known noise makers. If you have successfully done a recap, then you should be capable of replacing the transistors in the preamp sections with some guidance. Let us know if you would like to have a go at this.
Cheers
John
(PS - pete_mac on SNA is my son)
AU-7900 fuse resistors and VD112 Diodes. The photo is taken after a recap on hte power amp board, and the four 220 ohm fuse resistors (circled in green) and the four VD1212 diodes have been replaced
I also have recently worked on an AU-5900 - and no fuse resistors in this unit (at least no 1/2 Watt ones, there are larger fuse or NIR resistors but I have found these typically don't drift high).
Cheers
John
I also have recently worked on an AU-5900 - and no fuse resistors in this unit (at least no 1/2 Watt ones, there are larger fuse or NIR resistors but I have found these typically don't drift high).
Cheers
John
sKiZo
Hates received: 92644 43.20°N 85.50°W
Kevzep mentioned it in passing a while back, but it's real important to put the dogleg bends in the new resistors before mounting.
This stands them proud of the board and minimizes damage from heat or overload. Actually not a bad habit to get into with any light weight components that won't be prone to toppling over ...
Also good habit to insulate the long leads if you mount one vertically. Don't want those shorting if you happen to fat finger one while working on a board. Insulation stripped from 22ga hookup wire works well for that.
PS ... where's all the pics for the QRX receivers? Those got a TON of fuseables scattered about ...
This stands them proud of the board and minimizes damage from heat or overload. Actually not a bad habit to get into with any light weight components that won't be prone to toppling over ...
Also good habit to insulate the long leads if you mount one vertically. Don't want those shorting if you happen to fat finger one while working on a board. Insulation stripped from 22ga hookup wire works well for that.
PS ... where's all the pics for the QRX receivers? Those got a TON of fuseables scattered about ...
If absent from the original design, I use ceramic beads for lifting hot components, (or fuse resistor substitutes) off the PCB surface. This insulates the leads, holds the component firmly above the PCB surface, and... I think they look cool too
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