Heirloom item help please

[FrankSinatra]

Thanks Chris will work through these steps shortly

[FrankSinatra]

Tried each step Chris can’t see any changes by tapping chassis or valves.

Used servisol again but this didn’t change things either.

It’s like the sound poor speakers make at high volume, like a slight distortion/buz

Good example is playing “hound dog” this shows it in its worst condition, better on other records. Also noticeable on radio.

It’s only present on the left speaker, so when balance is at full left it’s more pronounced. Seems to change with each tone change but just along with the tone of that makes sense.

[Edward Huggins]

You've now been struggling with this for many months and 142 Posts. Best to get a Member here to look at it for you, there are many in your area. Put up a request on "Service Needed" on here. You won't be ripped off.

[Lucien Nunes]

It’s like the sound poor speakers make at high volume, like a slight distortion

Distortion can be a symptom of many things, not least the leaky capacitor problem frequently mentioned upthread. I can understand your reluctance to dig into the unit to extract the chassis, following the wise strategy of trying not to create new faults to add to the existing one. However, not checking for known troublemakers underneath is like trying to troubleshoot poor car performance without opening the bonnet. And at present you are driving it around without having checked the engine oil level for 50 years. It might be OK or it might be about to self-destruct, turning a simple, cheap and routine job into a major rebuild requiring difficult-to-source parts.

Especially as you now have distortion on one channel, checking and/or replacing those coupling capacitors is a top priority. If they turn out to be of a trustworthy type, then you can move on to other, less likely possibilities. It's also worth noting that leaky capacitors can cause volume and tone controls to become more crackly, because DC leakage current passing through pots makes them more sensitive to bad contact.

[FrankSinatra]

Thanks Edward and Lucien, I may take the plunge this weekend and take out the chassis for inspection, I took off the knobs to use some contact cleaner this week so I don’t think it will be as difficult in the end as I expected.

[FrankSinatra]

I’ve taken out the chassis was quite straightforward in the end.

[FrankSinatra]

Turns out the brown wires that seem to be randomly taped down with loose terminals end up here, what would they be for?

[FrankSinatra]

Think I have inadvertently cured the distortion, I thought while it was at it I’ll take out the speaker cone and see what it sounds like.

No more than finger tip pressure inside the cone and the distortion disappears, seems like it’s a vibration in the cone causing the noise?

[ms660]

Originally Posted by FrankSinatra

Think I have inadvertently cured the distortion, I thought while it was at it I’ll take out the speaker cone and see what it sounds like.

No more than finger tip pressure inside the cone and the distortion disappears, seems like it’s a vibration in the cone causing the noise?

Quite common, usually it's the voice coil rubbing.

Lawrence.

[Edward Huggins]

This sounds like the voice coil is rubbing because the cone has gone out of centre. This is not easy to fix and you may need to buy a new loudspeaker. Yours looks like an 8 x 5 inch unit with (probably) a 3 ohm impedance.

[FrankSinatra]

Thanks Edward, after a little tap and refit the distortion has gone for now and it sounds great again, if the issue reappears I will tackle it as you suggest.

[Lucien Nunes]

If the coil rubbing is caused by the speaker suspension sagging over the years under its own weight as it sometimes is, you can prevent it returning any time soon by refitting the speaker upside-down to how it was originally. It will then take a few decades to sag the other way. If the cause is a misshapen coil former, off-centre magnet etc it won't help, but won't hurt either.

Turns out the brown wires that seem to be randomly taped down with loose terminals end up here, what would they be for?

They seem to be the 230V AC power feed to the deck motor. The brown figure-8 cable from the power switch on the back of the volume control is jointed to the brown and black leads that are integral to the deck. If they are not properly insulated, which they should be because they carry mains voltage, you could remake the joints with any suitable type of terminals. A pair of Wago 221 lever connectors would be ideal. as they are fully insulated and quick and easy to fit and uncouple later if you want to pull the deck out for maintenance.

The two brown capacitors badged 'R.T.C.' appear to be the output valve grid coupling capacitors. These are the ones that you do not want to be faulty, lest they damage the output valves and transformers. Despite the 'R.T.C.' marking these appear to be rebranded Hunts Moldseals which are frequent troublemakers and ones that we would all instinctively change before powering up the chassis for the first time. If you intend to keep using this machine, I would strongly advise changing these to avoid it going up in a puff of smoke. They might be OK now but that's little help when they've gone bad and melted the transformers. In reality, they probably aren't OK now. A sharp close-up pic of the caps and the area around the bases of the EL84s would be helpful.

The only others that might be past their best and affecting the sound are the two cathode bypass electrolytics, seemingly mounted on spare tags on the tops of the output transformers. The remainder are mostly ceramic and not immediately suspect.

[peterpixel]

Is this the speaker with the missing screw? This sounds like the magnet has moved due to to the said screw not being there. I have,no doubt with many others,adjusted magnet position by tapping with a small hammer. Perhaps this epic should be called "The case of the missing screw". I now lower my head beneath the parapit. Peter.

[FrankSinatra]

Thanks for your help, I will look into what’s involved in changing the hunts capacitors now we have identified it as a potential problem.

[FrankSinatra]

Originally Posted by peterpixel

Is this the speaker with the missing screw? This sounds like the magnet has moved due to to the said screw not being there. I have,no doubt with many others,adjusted magnet position by tapping with a small hammer. Perhaps this epic should be called "The case of the missing screw". I now lower my head beneath the parapit. Peter.

Strangely it’s not the missing screw one it’s the opposite!

[peterpixel]

Even more mystifying,better keep original title. Peter.

[FrankSinatra]

I’ve posted in the help wanted section for some assistance on changing the capacitors, not comfortable with that myself but will do some digging as it’s surprising what you can become comfortable with after some research.

[Gabe001]

I think I have a spare like for like speaker replacement for you if you're struggling with it. Just pm the measurements and I'll double check with mine.

[FrankSinatra]

Thanks that’s great will have time this weekend to take it out and measure.

[Edward Huggins]

Originally Posted by FrankSinatra

Thanks Edward, after a little tap and refit the distortion has gone for now and it sounds great again, if the issue reappears I will tackle it as you suggest.

I'm having some difficulty in following your Posts as now having said "it sounds great again" - you seem to have moved on to changing some of the caps. What really needs to be done to this now then?