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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 2nd Mar 2021, 1:00 am   #61
Techman
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Default Re: Murphy A851G no sound to speakers. Tone arm fault on Garrard deck.

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Originally Posted by Techman View Post
If HT voltage had been checked first and the rectifier replaced with a diode and series resistor it would probably be up and running by now - there's been enough previous thread posted about this problem over the years.
I've never understood why some people reach for the soldering iron before reaching for their meter.
I agree.

Looking back at the first page of this thread I can start to see what's gone wrong. He's received well meaning but confusing advice. He was told to replace the 50uf capacitors, but unfortunately not which ones. Then in another post he was told to replace the same two capacitors again, but this time told they were shown in the 'second photo'. Unfortunately he didn't act on this correctly and decided to replace the two in one can in the 'third photo', but unfortunately he wasn't pulled up on this and so on. I think we have to be careful when giving brief instructions to an inexperienced person (I may have even been guilty of this myself in the past, but I try not to). The capacitors he was supposed to have replaced were the two grey cathode decouplers, although personally I've never found these to be a problem in this model and they're replacements anyway, so would have left them alone for the time being, certainly when advising a novice - the least he has to worry about the better. The main two in one smoothing capacitor definitely didn't need replacing in my opinion, but it's done now and still not working - at least the original faulty rectifier has been replaced.
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Old 2nd Mar 2021, 1:08 am   #62
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Default Re: Murphy A851G no sound to speakers. Tone arm fault on Garrard deck.

Actually I've noticed that he was told on the second occasion to just replace one 50uf capacitor in the 'second photo', which then confused him and made him pull out the smoothing can in his 'third photo', then he was told the rectifier would be fine, which it never is in these players.

Edit: Sorry, I'll take that back regarding the rectifier - he'd mentioned the replacement diode and resistor in the previous post that was being referred to as fine, as that was going to be the new replacement parts he was going to obtain and fit. Now I'm getting confused - I'd better shut up!
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Old 2nd Mar 2021, 1:41 am   #63
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Default Re: Murphy A851G no sound to speakers. Tone arm fault on Garrard deck.

Just thinking about this again, back in post #1 he said that there was no sound even when touching the head wiring (or something similar to that indicating a buzz test I think). The truth is that these players will still work with an HT down to below 50 volts, but they sound rather rough and not very loud. Then he said he'd fitted EL84 valves instead of the correct ECL86 types - what was he thinking and why did he do this? So there has always been an original fault of no audio through the amplifier from the cartridge to the speaker, but he got side tracked regarding 50uf capacitor replacements.
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Old 2nd Mar 2021, 10:58 am   #64
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Default Re: Murphy A851G no sound to speakers. Tone arm fault on Garrard deck.

What's done is done. Let's wait for the result of the buzz at the volume control centre tag. If that fails we'll have to assume that a capacitor that should be coupling isn't.
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