Apparently its a leak delta 70 in disguise.
Anyhow, when I shut it down it sounds like a sipper being undone, it starts as a low tone then gets high pitched before fading out, this is only in the left channel, there is a bit of a thud from the right but its not really too bad.
The thing has been in an attic for many years.
The problem happens on all source selections and is not volume dependant.
When working it seems to work fine, Just this noise as soon as I switch it off.
Any ideas?
The manual for the Leak Delta 70 is here in HIFIEngine. I have read that the leak and wharfedale amps are identical.
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Anyhow, when I shut it down it sounds like a sipper being undone, it starts as a low tone then gets high pitched before fading out, this is only in the left channel, there is a bit of a thud from the right but its not really too bad.
The thing has been in an attic for many years.
The problem happens on all source selections and is not volume dependant.
When working it seems to work fine, Just this noise as soon as I switch it off.
Any ideas?
The manual for the Leak Delta 70 is here in HIFIEngine. I have read that the leak and wharfedale amps are identical.
Login - HiFi Engine
First things that come to mind are dried out electrolytic caps. Something of this age should really be rebuilt with new replacements.
Thuds and noises on switch on and switch off are "normal" with any capacitor coupled amp that doesn't employ a dedicated relay to give a speaker delay when powering up.
So I suspect yours is a little worse than normal given the age and probability of cap issues, but you will probably never get it silent.
Thuds and noises on switch on and switch off are "normal" with any capacitor coupled amp that doesn't employ a dedicated relay to give a speaker delay when powering up.
So I suspect yours is a little worse than normal given the age and probability of cap issues, but you will probably never get it silent.
No, they use electrolytics - but the larger ones aren't fitted on the boards.
As it's only on the left channel, try swapping the left and right boards over, and confirm the fault swaps channels (proving if it's on the board or no).
Film caps if used would tend to be small values. You would need to look and make a quick evaluation of what is fitted. I'm guessing these are all "axial" caps where a lead comes from each end of the cap rather than more modern radials which have both leads together at the same end of the cap. It no big deal, just check physical sizes of things before ordering, modern caps will be tiny in comparison. Axials are still available but tend to be dearer and available in limited values and ratings.
The fact the volume control has no effect means the problem is specific to that one channels power amplifier.
The fact the volume control has no effect means the problem is specific to that one channels power amplifier.
This might be quicker for reference as the above link needs amendment. It comes by way of Paul Kemble's excellent site for vintage UK audio reference.
A Paul Kemble web page - index to 'sound' webpages.
Hmm...you mean my link Mooly? Perhaps that part of of the spam doesn't travel to Oz as I can log in on another PC also, without getting that sort of message but of course, Angelfire is a massive spam generator - I guess they keep only the best for the the home crowd!
This link should divert people to the registration process which may be needed at Hifiengine. Apolgies to any who suffered that link's problems.
Leak Stereo 70 Manual - Stereo Integrated Amplifier - HiFi Engine
This link should divert people to the registration process which may be needed at Hifiengine. Apolgies to any who suffered that link's problems.
Leak Stereo 70 Manual - Stereo Integrated Amplifier - HiFi Engine
Err... yes lol
Picture hosting and file sharing sites have the same problem. I always use task manager to close IE if anything like pops ups.That's very odd guys, I switched the two power amp boards, left to right and right to left and the problem is now gone, all I have now is a noisy volume/power switch.
I wonder if it was dirty contacts on the board or the socket it locates into?
Anyhow, I did notice the power on bulb was hunting slightly however this also seems to have got better with a few on and off cycles, I wonder if the thing just needs a good clean?
What do you guys recommend to clean and lubricate dirty old pots and switches?
I wonder if it was dirty contacts on the board or the socket it locates into?
Anyhow, I did notice the power on bulb was hunting slightly however this also seems to have got better with a few on and off cycles, I wonder if the thing just needs a good clean?
What do you guys recommend to clean and lubricate dirty old pots and switches?
Anything is possible I guess and yes, contacts are always a potential trouble spot. It could also still be cap related. Old caps that have been unused for a long time sometimes need to "reform" such that the leakage current drops to acceptable limits.
Cleaning pots and switches. Pots that are noisy do respond to cleaning but its often temporary. If no one was looking a quick squirt with WD40 can help but you have to get it into the pot. I wouldn't recommend that on the mains switch part though. There is a new WD product specifically for electronic work but its quite expensive, around £6 or more I seem to recall. Noisy pots are best replaced really if possible .
Cleaning pots and switches.
Pots that are noisy do respond to cleaning but its often temporary. If no one was looking a quick squirt with WD40 can help but you have to get it into the pot. I wouldn't recommend that on the mains switch part though. There is a new WD product specifically for electronic work but its quite expensive, around £6 or more I seem to recall. Noisy pots are best replaced really if possible .
That's very odd guys, I switched the two power amp boards, left to right and right to left and the problem is now gone, all I have now is a noisy volume/power switch.
I wonder if it was dirty contacts on the board or the socket it locates into?
Anyhow, I did notice the power on bulb was hunting slightly however this also seems to have got better with a few on and off cycles, I wonder if the thing just needs a good clean?
What do you guys recommend to clean and lubricate dirty old pots and switches?
I recommend WD40 (or similar - we actually use Servisol Super 40) - excellent for the pots, switches and the contacts on the PCB edge connectors.
I've been using it professionally for over 30 years, as it's proved to be much more effective than specific 'switch cleaners'.
However, a number of people seem to be against using it, and quote all kinds of side effects, which I can only imagine they have only heard stories of and never actually seen in practice? - I've never seen any bad effects from using it, nor heard of any.
The PCB contacts have always been a source of trouble, simply removing the board, a little squirt of WD40, and they are permanently cured.
Silly question but will wd40 lubricate the pots sufficiently?
The volume pot is noisy, then I run it through a few cycles and its silent, but if left for a few moments its noisy again.
The front plate and nobs all have a heavy , thick greasy hard to clean coating on them so my guess is its been in an environment such as a kitchen, so Im assuming the internals have suffered the same coating.
The volume pot is noisy, then I run it through a few cycles and its silent, but if left for a few moments its noisy again.
The front plate and nobs all have a heavy , thick greasy hard to clean coating on them so my guess is its been in an environment such as a kitchen, so Im assuming the internals have suffered the same coating.
The badge has the T symbol of British Telecom from the 1980's ? Maybe previously owned by an employee... who knows
Pots really should run dry, its just that flooding them with a lubricating cleaner happens to cover the problems. The only way to repair a pot (and we used to do this all the time on single gang controls, duals it may not be physically possible) was to open the thing up, clean the track with a cotton bud and cleaner such as WD and then retension (if needed) and reposition (the important bit) the wiper so it runs on fresh unworn resistive track.
Pots really should run dry, its just that flooding them with a lubricating cleaner happens to cover the problems. The only way to repair a pot (and we used to do this all the time on single gang controls, duals it may not be physically possible) was to open the thing up, clean the track with a cotton bud and cleaner such as WD and then retension (if needed) and reposition (the important bit) the wiper so it runs on fresh unworn resistive track.
Long ago, companies such as CRC campaigned aggressively against the use of WD and similar inexpensive GP spray lubricants. They distributed technical papers which were about the only source of credible information so their message has even outlived their products. A major application then was high-reliability relay contacts, where the sulphur contaminants in WD's petroleum distillate could cause problems. (anyone recall the enormous banks of relays used in old telecomms and industrial control equipment?
)Petroleum product - Wikipedia, the free encyclopedia
In general service use, I agree that much that is parroted about WD40 is stuff and nonsense but I think there are occasions where a better or at least higher purity product, should be used.
As a service tech back in the 80's and 90's we used all the "official products", Electrolube, Servisol etc and found that they all rotted plastic over months and years. Many TV's and the like had to be scrapped because the cabinets literally crumbled away if a tech had squirted the stuff everywhere. The best product at the time was an RS spray called something like "water displacement", I forget now, but it was the best of the lot.
Same problem with some anaerobic thread locking compounds, they rot plastic.
Same problem with some anaerobic thread locking compounds, they rot plastic.
Until the earth's ozone layer was an issue,"Freon" or CFCs were the general aerosol propellant. The vapour and liquid rapidly attack thermoplastics like ABS, polystrene and acrylics. When those CFCs were phased out from the 1990s, they were largely replaced by "hydrocarbon" types which makes the cans dangerous flamethrowers, so now CO2 is sometimes used but is quite safe on plastics, as long as the product is too.
http://www.boconline.co.uk/en/produ...pellants/propellants.html2pdf?out=propellants
http://www.boconline.co.uk/en/produ...pellants/propellants.html2pdf?out=propellants
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