Hello all,
Got a Sugden A88 with a few burnt components, but can't seem to find a schematic or service manual anywhere?
Anyone have a copy?
Cheers!
Got a Sugden A88 with a few burnt components, but can't seem to find a schematic or service manual anywhere?
Anyone have a copy?
Cheers!
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The A88 was a king size version of the classic A48 series II. It had a power output of 80 Watts per channel and doubled this into 4 Ohms. Each channel had its own transformer with four output transistors per channel. It featured two tape inputs, tuner input, as well as two phono inputs with a sensitivity selector for MM cartridges. Apart from tone controls it also had a number of slope filters so it was a very powerful and versatile amplifier.
convert sugden a88 to power amp
Sugden a88/a48 pot values
But this is 5 years ago 🙁
Sugden A88
But this is 9 years ago 🙁
convert sugden a88 to power amp
Sugden a88/a48 pot values
But this is 5 years ago 🙁
Sugden A88
But this is 9 years ago 🙁
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Hi, thanks, had seen some of those posts, but not all, will look over them closer tomorrow.
Had no idea it was such a rare amp, seems like it is well worth fixing up.
will post an update if I get anywhere with it.
thanks again.
Had no idea it was such a rare amp, seems like it is well worth fixing up.
will post an update if I get anywhere with it.
thanks again.
So far got the current stable via the fuse, at 160mA need to switch the mid point trims out now too, as they are jumpy.
However the voltages seem hot at 85V, on the main rails, the main filter caps are only 100v, this is running it at 220v. not the full 243v round here.
If anyone else has one of these 100% recommend replacing all four trim pots, they have likely been baked over the years..
However the voltages seem hot at 85V, on the main rails, the main filter caps are only 100v, this is running it at 220v. not the full 243v round here.
If anyone else has one of these 100% recommend replacing all four trim pots, they have likely been baked over the years..
Sugden A88 schematics
Hello, got one A88 for repair on my bench.
Found the A48II schematics supposed to be similar ???
Yes I found those trimpots to be not exactly stable.
Also found some 580 ohms 2 watts resistors to be overheated on one channel.
Did not powered with a variac yet, as I want to make sure i would have more information, especially the A88 schematics ??
Thanks
Hello, got one A88 for repair on my bench.
Found the A48II schematics supposed to be similar ???
Yes I found those trimpots to be not exactly stable.
Also found some 580 ohms 2 watts resistors to be overheated on one channel.
Did not powered with a variac yet, as I want to make sure i would have more information, especially the A88 schematics ??
Thanks
The trim pots on the pre amp board calibrate the high and low freq response, from what I can tell, handy as this A88 had always had +4db up to about 400hz iirc, the outer edge trim is directly connected to the BASS eq knob.
the power supply boards in these seem pretty underrated, the first one my friend bought was serial 003 that one smoked, they then sent this one out and it lasted a while, feels like it wasn't an entirely matured design though 🙂
the power supply boards in these seem pretty underrated, the first one my friend bought was serial 003 that one smoked, they then sent this one out and it lasted a while, feels like it wasn't an entirely matured design though 🙂
A48 circuits have modes. A common ideology remains. This is an AB PP amplifier with a high quiescent current (A up to 10 W). At the output there are discrete Darlingtones npn and pnp. Output capacitor.
One stage of voltage amplification. Emitter follower.
The midpoint of the exit, the quiescent current and the NFB depth are adjustable.
One stage of voltage amplification. Emitter follower.
The midpoint of the exit, the quiescent current and the NFB depth are adjustable.
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I have a pre-amp section available if anyone wants one - have just stripped everything out of mine and replaced it with just a volume control. The phono connector board was also dumped as it was a mess and replaced with just one as I only use it for laserdiscs anyway.
Phil
Phil