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Old 27th February 2011, 02:07 PM   #1
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Default Arcam Alpha 7 & CD8se

I am once again having problems with a 7 & 8SE. My question is; To convert a 7 to a 8se is it simply taking out the link board and fitting the dac board, or are there other links or bits to add/subtract. Any help would be gratefully welcome. I am going mad as the 8SE board is faulty but I have a good 7 board I can use. Barry
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Old 28th February 2011, 12:07 PM   #2
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The problem with the 8SE board is both resistive fuses (R44 and R45) have blown, for no apparant reason. Both regulators read OK. I don't want to replace them without knowing the fault as I would have to use the ones on the 7 board. I have tried the DAC in the 7 board and although it works for a while I get distortion and skipping after a few minutes which leads me to think I have a dodgy component on the DAC penninsula or there is some other mods to perform before the board can be used.
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Old 4th March 2011, 07:17 PM   #3
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Have you asked Arcam ?
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Old 7th March 2011, 01:55 PM   #4
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Soory for delay Jon, iv'e been away. Thank you for the response. I did ask Arcam and they sent instructions. It's as simple as I thought. Now iv'e got to find the problem with the DAC. I think it may be one of the ribbons. Regards Barry
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Old 7th March 2011, 05:07 PM   #5
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Barry, R44/R45 are on the main board ? If the +/-18V just feeds the DAC board do the MFR25 resistors blow when the DAC board isn't connected ? If they do then check the components around Z204/Z205. Otherwise I guess you'll just need to work your way through the DAC pcb starting at the +/-15V regulators Z16 and Z17. Checking the voltages/ripple on the main board power connector would probably be a good place to start.
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Old 7th March 2011, 07:19 PM   #6
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Thanks Jon, I'm now using the 7 board which is OK. I now have a problem where the DAC board did work for a while but now doesn't. The main 7 board is OK because if I remove the DAC and replace the jumper board it works as a 7 player,
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Old 7th March 2011, 08:55 PM   #7
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Barry, so to confirm you have two problems :-

1. The two resistors on the 7 mainboard (R44/R45) blow when you plug the 8SE DAC into it.

2. When it 7 mainboard is running on its own (no 8SE DAC board fitted) the player starts to skip after a few minutes.

Distortion and skipping - have you looked at the supply rails on the mainboard with a scope and checked the clock on the mainboard, perhaps the supplies are collapsing and/or the clock is becoming unstable.

Power supply overload - have you checked continuity of the ground between the mainboard and the DAC board through the SK204 ribbon and have you tested all of the electrolytics on the DAC board ?
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Old 7th March 2011, 09:11 PM   #8
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Hi Jon, No. The 7 mainboard is OK. The fuses do not blow. This happened with the 8SE mainboard. I have now disregarded that one for the time being. I have now fitted the 7 mainboard and all is well with it. When I fit the 8SE DAC board it does not work, although it did for a time. I did get distortion and skipping, and then it started working when hooked up without fitting permanently. but now I get nothing.
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Old 7th March 2011, 09:29 PM   #9
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Sorry I misunderstood, I thought you had a 7 mainboard and a 8SE DAC board. So you have a 7 mainboard (with DAC components fitted) and an 8SE mainboard (without DAC components fitted) and 8SE DAC board ? I have a couple of mainboards without the DAC components fitted + 9 DAC boards and (I think) a mainboard with the DAC components fitted which must have come from a 7.

The jumper board routes the DAC signals and clock either through the mainboard or from the DAC board to the mainboard. When a DAC board is fitted I assume you remove the jumper board. If you get nothing with the 8SE DAC fitted have you checked the clock signal coming from the DAC board ?

Going back to the fusible resistors did they blow on the 8SE mainboard with the 8SE DAC fitted or just with the 8SE mainboard powered on its own ?
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Old 7th March 2011, 10:13 PM   #10
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I haven't checked the clock signal. I do not have an oscilloscope. The fusible resistors on the 8SE mainboard were blown when I got the player.
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