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  #11  
Old 19th September 2015, 12:00 PM
Cyprus Martin Cyprus Martin is offline
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Default Re: MY Phono 3 has started bop bopping

Hi Bob,
The 4 x 10uF 400v electrolytics came this morning (well done Farnell). I put them in but the noise was still there.
On to the PSU, I removed all the electrolyics and replaced them, checked for dry joints, checked all the voltages, all OK, plugged everything back in alas the noise is still there.
If I had any hair it would be torn out by now.
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  #12  
Old 19th September 2015, 12:43 PM
bob orbell bob orbell is offline
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Default Re: MY Phono 3 has started bop bopping

Don't get too stressed Martin, it is something very simple, I don't think it can be power supply problems, because of the noise only on one channel, question, is it standard, or have you modified it at all, dose it have the three position subsonic filter, are all the components as supplied, a picture may help, have you tried reversing C11/12, run a test for continuity over everything including the cables. BOB
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  #13  
Old 19th September 2015, 02:27 PM
Cyprus Martin Cyprus Martin is offline
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Default Re: MY Phono 3 has started bop bopping

Hi Bob,
Firstly the sound is now coming equally from both channels. Maybe points towards a problem with the PSU?
Regarding the PSU3, the only changes I made from the original was to upgrade the bridge rectifier with four 1N5822 diodes.
Regarding the Phono3 the only thing from the original was to by-pass R7/8 with a 220uF 10V capacitor, which I have tried removing to see if it made any difference (it didnít).
I have re-soldered all the joints on the Phono3 and the connecting power cord. I havenít done the same with the PSU3 as all the voltages are correct and I had one hell of a job re-fitting the voltage regulator.
I haven't tried reversing C11/12 yet as I took a break to have some tripe and onions!
Regards
Martin
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  #14  
Old 19th September 2015, 04:22 PM
Richard Richard is offline
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Default Re: MY Phono 3 has started bop bopping

Did you change the 100uF 450V cap inside Phono Martin (C20 in Phono3 or C17 in Phono3S)?

(This cap was moved from PSU to the Phono box end of the umbilical with the development of Phono3 from Phono2, where the supply impedance sometimes caused motorboating as you are experiencing, sorted by John iirc. Thoughts are that if this cap is getting tired it may be the problem. Motorboating could affect one or both channels even with a common PSU as each channel will have slightly different electrical properties/layout etc. It may be incipient and just need a small change/aging to set it off.)
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  #15  
Old 19th September 2015, 06:37 PM
Cyprus Martin Cyprus Martin is offline
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Default Re: MY Phono 3 has started bop bopping

Hi Richard,
On my Phono3 the one that you are referring to is C17 not C20, anyway yes I did change it and it made no difference so just to be on the safe side I've changed it again.
I've now rebuilt the PSU3 with all new twisted wires for the connections and once again all the voltages are correct.
Connected it all up and the noise is still there.
A couple of things though, I noticed that some of the voltages in Phono3 were quite a bit below where they should be so I changed V3 and that brought everything back as it should be, I mentioned already the when I switch off the PSU3 that the noise increases for a short while before dying away. Also when I touch the front knob to switch it off the noise diminishes a little. The PSU3 is earthed across to Phono3 and to the turntable, I've tried disconnecting this but that has no effect.
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  #16  
Old 19th September 2015, 06:52 PM
bob orbell bob orbell is offline
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Default Re: MY Phono 3 has started bop bopping

OK, so the only thing I can now suggest is to connect a 100uF 450v capacitor to position C4 in the PSU, you can use wires to connect it, this will save you removing the board, and try it again, a word of caution, make sure that all the capacitors are discharged, and the polarity is correct, before soldering and when you remove it, this size of capacitor stores considerable power, and may kill you. BOB
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  #17  
Old 19th September 2015, 07:15 PM
Cyprus Martin Cyprus Martin is offline
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Default Re: MY Phono 3 has started bop bopping

Thanks Bob, I'll try that hopefully without ending up in the great HiFi DIY in the sky! As you can see from my previous post I ended up stripping the PSU3 down and rebuilding it without success.
I've had another thought, I still have a PSUll in my garage but I did raid it for parts some time ago. Does anyone still have a parts list and wiring diagram for this? As far as the parts are concerned I think that I only need the ZD1 and D5 and D6, the rest I'm sure I'll have in the garage.
If I can get this working then it should tell me whether that PSU3 or the Phono3 need looking at.
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  #18  
Old 19th September 2015, 07:23 PM
bob orbell bob orbell is offline
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Default Re: MY Phono 3 has started bop bopping

The PSU II is the same as the III apart from the regulator and the to diodes, you only need the zener if you use PRE II as it runs at 100 volts, the phono voltage is the same for both II and III, so if you are using PRE III, the zener is left out. I do have the build instructions on paper only. BOB
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  #19  
Old 19th September 2015, 08:01 PM
Richard Richard is offline
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Default Re: MY Phono 3 has started bop bopping

So yours is Phono3S Martin. Did you fit the low filters and does the selected position have any effect on the problem?
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  #20  
Old 19th September 2015, 08:06 PM
Cyprus Martin Cyprus Martin is offline
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Default Re: MY Phono 3 has started bop bopping

Hi Richard, I'm confused now (doesn't take a lot!) The assembly instructions says WDPhono3 and there is nothing in them regarding selecting filters.
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