Well, it emerged that my once lovely Au51p needed a re-cap.
http://www.pinkfishmedia.net/forum/showthread.php?t=190754
Having a somewhat technical background I looked into what I'd need to buy and (more importantly) learn to do it myself, and decided - it wasn't happening.
Thankfully, Pete Maddex, of this parish, offered to do it for me. All I had to do was find out all the values, order them, and get everything to Pete.
I live in Norfolk, he lives in Notts.
We swapped several emails (which resulted in my Xerces PSU being added to the recap list), I took lots of geeky macro photographs of my amp's boards, and capacitors (all 105°C this time) were duly ordered, as well as a pair of speaker relays.
The total parts bill was 75 quid, for amp and PSU. Given the current/original retail cost of the units, this is absurd.
And so to Pete's; we were made most welcome (after a long drive, starting at 6 in the morning).
We plugged the Sugden in to warm up, and had coffee; Pete then wired the Sugden in (pausing only to physically chisel his massive 50Amp connectors so they fitted), and we auditioned; the sound was "interesting" - decent bass extension and control, an overall sweet sound, but appallingly muddled if anything at all complex happened. In a word - broken.
"We" (that is Pete) started on the PSU board, including the speaker relays.
Moving to the Amp boards, Pete started unsoldering the power trannies; the leads on the regulator chips (also bolted to the heat sink) looked long enough to be left in situ. Actually, it transpired that the rear of the board could - just - be accessed without unsoldering the trannies either, although it did flex their leads a bit.
Pete did sterling work, (un)soldering barely accessible components. We had a somewhat tense moment when we realised that the capacitor polarities are NOT symmetrical on the mainly symmetrical board. My careful photographs and printouts were somewhat hurriedly updated from the (other) as yet untouched amp board!!
Having put everything back together, Pete used his handy variac to perform basic tests. (PSU board has input voltage, not much AC after the rectifiers, reasonable amounts of DC, nothing goes bang, no magic smoke).
So Pete wired it into his lovely Shahinian Arcs. Not bad - on the left channel. Nothing on the right.
Back to the workshop, and Pete showed his practical diagnostic skills. I'd have been trying to work out the details of the entire circuit; Pete took the pragmatic view that it was probably something he'd done. A physical check revealed that the heavy duty speaker wire from the PSU/Switching board to the speaker terminal had simply fatigued and broken off. One resolder later, a retest.
Good - we have stereo, but with some highly odd distortion on one channel.
Again, "pragmatic Pete" got out, not an oscilloscope or a meter, but a magnifying glass, and systematically rechecked the soldering and tracks of each replacement cap. Ah hah! A fault. Out comes the soldering iron.
Back into the system and - ooh, that sounds rather nice (Pete's tweaked CD player, pre-amp and yummy speakers may have been a factor). It looks like I've got a working Au51p again! My Sugden might not be a match for Pete's modified Hackernap pair, but it'll serve.
After this, the Xerces PSU was an anticlimax, since it was mechanically quite simple to completely remove the PCB allowing full access. Pete's experience (and box of spares) came to the fore, since he happened to have the neccessary washers and thermal paste to remount the active components. He's also worked on his own Xerces PSU before.
So - what have I learnt?
* Hifi isn't magic - it's just electronics
* Pragmatic approaches can save time
* Sugden made some decent amplifiers
* Pete Maddex is a very nice guy
* you don't notice very gradual degradation of sound
My very grateful thanks to Pete, who turned my Sugden from a doorstop into a decent amplifier.
BugBear
PS I got a head cold during the next few days and couldn't hear anything properly at all
PPS My CD player is currently not working
http://www.pinkfishmedia.net/forum/showthread.php?t=190754
Having a somewhat technical background I looked into what I'd need to buy and (more importantly) learn to do it myself, and decided - it wasn't happening.
Thankfully, Pete Maddex, of this parish, offered to do it for me. All I had to do was find out all the values, order them, and get everything to Pete.
I live in Norfolk, he lives in Notts.
We swapped several emails (which resulted in my Xerces PSU being added to the recap list), I took lots of geeky macro photographs of my amp's boards, and capacitors (all 105°C this time) were duly ordered, as well as a pair of speaker relays.
The total parts bill was 75 quid, for amp and PSU. Given the current/original retail cost of the units, this is absurd.
And so to Pete's; we were made most welcome (after a long drive, starting at 6 in the morning).
We plugged the Sugden in to warm up, and had coffee; Pete then wired the Sugden in (pausing only to physically chisel his massive 50Amp connectors so they fitted), and we auditioned; the sound was "interesting" - decent bass extension and control, an overall sweet sound, but appallingly muddled if anything at all complex happened. In a word - broken.
"We" (that is Pete) started on the PSU board, including the speaker relays.
Moving to the Amp boards, Pete started unsoldering the power trannies; the leads on the regulator chips (also bolted to the heat sink) looked long enough to be left in situ. Actually, it transpired that the rear of the board could - just - be accessed without unsoldering the trannies either, although it did flex their leads a bit.
Pete did sterling work, (un)soldering barely accessible components. We had a somewhat tense moment when we realised that the capacitor polarities are NOT symmetrical on the mainly symmetrical board. My careful photographs and printouts were somewhat hurriedly updated from the (other) as yet untouched amp board!!
Having put everything back together, Pete used his handy variac to perform basic tests. (PSU board has input voltage, not much AC after the rectifiers, reasonable amounts of DC, nothing goes bang, no magic smoke).
So Pete wired it into his lovely Shahinian Arcs. Not bad - on the left channel. Nothing on the right.
Back to the workshop, and Pete showed his practical diagnostic skills. I'd have been trying to work out the details of the entire circuit; Pete took the pragmatic view that it was probably something he'd done. A physical check revealed that the heavy duty speaker wire from the PSU/Switching board to the speaker terminal had simply fatigued and broken off. One resolder later, a retest.
Good - we have stereo, but with some highly odd distortion on one channel.
Again, "pragmatic Pete" got out, not an oscilloscope or a meter, but a magnifying glass, and systematically rechecked the soldering and tracks of each replacement cap. Ah hah! A fault. Out comes the soldering iron.
Back into the system and - ooh, that sounds rather nice (Pete's tweaked CD player, pre-amp and yummy speakers may have been a factor). It looks like I've got a working Au51p again! My Sugden might not be a match for Pete's modified Hackernap pair, but it'll serve.
After this, the Xerces PSU was an anticlimax, since it was mechanically quite simple to completely remove the PCB allowing full access. Pete's experience (and box of spares) came to the fore, since he happened to have the neccessary washers and thermal paste to remount the active components. He's also worked on his own Xerces PSU before.
So - what have I learnt?
* Hifi isn't magic - it's just electronics
* Pragmatic approaches can save time
* Sugden made some decent amplifiers
* Pete Maddex is a very nice guy
* you don't notice very gradual degradation of sound
My very grateful thanks to Pete, who turned my Sugden from a doorstop into a decent amplifier.
BugBear
PS I got a head cold during the next few days and couldn't hear anything properly at all
PPS My CD player is currently not working
