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CAudio SR808

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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Topic: CAudio SR808
    Posted: 24 January 2020 at 6:42pm
So....After many years of wanting one, I had given up. Until yesterday, picked (sort of) one up today. To say it's a bit rough is an understatement, but hey ho. Looks like  its had more fingers inside than Katie Price.

The seller said one channel is quieter than the other, so need to get it to someone who will service it and replace parts as required. I intend to get this back up and fully working. 

One thing. Would anyone have a photo of the back of one please, I just want to compare. 
In bass no one can hear you scream!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 24 January 2020 at 8:50pm
Funnily enough i saw that advertised on FB, £150 i think. The usual rust,but they all have that. Think he said the fans are worn out too? Noisy bearings he means? But they should be quite easy to replace. Odd one channel is working but quieter, would be interesting to see photos of the inside?


Edited by jbl_man - 24 January 2020 at 8:53pm
Be seeing you.
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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 24 January 2020 at 9:52pm
I did some research and from about 2 years ago there was an 808 with the same symptoms, although the lad I bought this off said it started over the last few weeks. Someone has deffo been in and done some work as there is some pretty awful soldering going on. One of the slides on the back looked o be in the wrong position, who knows. 

I have drilled out all the screws that wouldnt come out with a screwdriver and replaced them. I realised as I was screwing the lid back on that someone had swapped the lid for the base. 

Time for a proper engineer to service it I paid a low price for it. So let's get it running properly so I can have confidence in it. 

I had to laugh when I picked it up. I had to waddle to the van with it...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 24 January 2020 at 10:24pm
A wheel board is a lovely thing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 10:38am
 Wow, an 808, you don't see many of those! I loved my old Xr3801's, the 'like a tank' build quality, the sound quality and the power, they just never seemed to run out of steam. What I didn't like was having to put them all in separate racks just so I could  move them. Any chance of some pics? Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 8:45pm
Well. That was dramatic. Thought I would just plug it in and test it at least goes through the stages of waking up. 

Turned on, hummed and went bang....Bit of smoke and the house stinks...lol.

Took the top off as much to make sure it was not going to burst into flames (after pulling the plug obviously) and it looks like the resistor on the soft start has exploded. 
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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 9:23pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 9:23pm
Originally posted by midas midas wrote:

Well. That was dramatic. Thought I would just plug it in and test it at least goes through the stages of waking up. 

Turned on, hummed and went bang....Bit of smoke and the house stinks...lol.

Took the top off as much to make sure it was not going to burst into flames (after pulling the plug obviously) and it looks like the resistor on the soft start has exploded. 
 
 Ah bugger, from my experience of C Audios that either means the soft start relay is stuck or more likely (and unfortunately) blown output transistors. 

 Are you going to repair it or take it back for a refund?
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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 9:25pm
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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2020 at 9:27pm
I fully intend to get it back on its feet and reliable.

If you look at the Gold resistor one end is missing with a strand of wire poking out. I assume that has protected things further into the main body of the amp.

I need to get it to someone who knows how to work through and fix it.

NOW....you say blown output transistors, that would suggest the seller was telling the truth about going quiet on one channel.

Edited by midas - 25 January 2020 at 9:30pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 26 January 2020 at 7:15pm
Things to check on the SR808 are as follows:

1. The soft start resistor is a 47R 50 Watt Aluminium clad resistor.
2. The soft start protection fuse should be a 1.6A Quick Blow (THIS IS THE ONLY FUSE YOU USE & NO OTHER TYPE), if it blows, there is a fault and replace with the same type.
3. Check the soft start & channel protection relays are o.k. and not stuck etc and change over O.K.
4. Each driver PCB check R14 & R50 (were 24K 1/2 Watt now changed to 27K 1 Watt).
5. Measure across D18 & D19 (Aux power supply to supply the TL071 op-amps) this should be 18 Volts.
6. Looking at your pictures, there seems to be some wire messing around by the XLR inputs, check this.
7. The output MOSFET's are normally bomb proof so a MOSFET blown is a rare (but not impossible). You could measure each MOSFET rail PCB between the Source & Drain and if low ohms (near short) would indicate a faulty MOSFET on that PCB rail. To isolate which MOSFET is faulty, just de-solder each Drain on every MOSFET on that row and then again measure each MOSFET and this should show you which one is faulty.
8. The bridge rectifiers may also be faulty and would need checking with a meter (diode check).

Please also be careful as there is high voltages around and the above MUST be done by a engineer or someone who knows about power amplifiers. Wink
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midas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote midas Quote  Post ReplyReply Direct Link To This Post Posted: 26 January 2020 at 11:57pm
Simon, thank you. Yes someone has been in there messing about by the looks of it. 

I do not intend to poke about any further. Happy to take the top off and have a look while keeping fingers out of the way, but but not willing to put said digits into electrical components. 
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