Bought Altec Lancing and Sugden Monoblocks £100

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Paul Barker
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#31

Post by Paul Barker »

So we have end of 1975 he bought the first one and January 1977 he had saved up enough money to buy the second.

not exactly because we don't know Sugden's stock levels, but actually at that very time while I was studying a degree in Economics business was starting to adupt a "just in time" stock control system as it was learned how much money was wastefully tied up in stock. So it is reasonable to expect these dates are within a month or two of production.

Sugden will know exactly from the serial numbers though.

I shall be writing to them. Might get more acurate schematic.

Haven't a clue how to decipher a BJT schematic, though it has to be said I am a beginner here. Never saw myself learning BJT topology. dismissed it out of hand many years ago.

Tres Idiot.
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#32

Post by pre65 »

Paul Barker wrote: You are a star with a reasonably priced car. How great it is to have the worlds authority on Nixie tubes in our midst.
Yep. :wink:

I know FA about everything. :lol:
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#33

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pre65 wrote: are they genuine, or cheap Chinese crap ?

this is the problem we are faced with today.

I try not to deliberately order from China or the far east because of this but some of these UK sources have likely done just that and then repackaged them.

I am still waiting for two Alen Bradley's accidentally ordered from far east (didn't check origin) about a month ago. Go to open an item not received case and "not due until " then some mythical time period a month from now.

How did they manage to swing that.

Two resistors from anywhere in the world shouldn't take 2 months.

Tres idiot for ordering them.

When they arrive I'll have long forgoten what they were for.

So how to buy genuine reliable Shottky?
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#34

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pre65 wrote:
Paul Barker wrote: You are a star with a reasonably priced car. How great it is to have the worlds authority on Nixie tubes in our midst.
Yep. :wink:

I know FA about everything. :lol:
You sir have proved yourself to be the most stable plodder we have ever had , shows a genuin interest in anyone who is trying, not scared to ask the dummest questions on earth, have 9 lives and alive to tell the tale, and a pretty damn fine all round good egg.

But I didn't say it because I don't want you getting too big headed to fit into your open face pre 65 crash hat.
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#35

Post by jack »

Paul Barker wrote:So how to buy genuine reliable Shottky?
Buy 'em from Farnell... http://uk.farnell.com/fairchild-semicon ... dp/1467531

The SB5100s would probably be fine (you need at least 100V, 3A) and with their lower forward drop they would run cooler.

However, they also turn off faster and generate a certain amount of nasty noise, so I always put a 100n across each one, as in my Quad 405-2 rebuild (yes, I know those aren't schottky diodes, but all diodes generate a certain amount of switching noise, so its good practice in audio kit to bypass them...)

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#36

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Oh so Schottky not necesarily sound better.
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#37

Post by jack »

Paul Barker wrote:Oh so Schottky not necesarily sound better.
"Hollow state" != "solid state".

I have never ever heard any difference in a decent SS amp by changing between standard recovery and schottky rectifiers.

Where they win is in lower power dissipation, e.g. the SB5100 Vf is 850mV and the 1N5401 Vf is 1.2V.

As, for a full bridge, two are conducting at any time, for the 1N5401s, we get 3A x 2.4V loss, i.e. 7.2W

For the SB5100s, we get 3A x 1.7V = 5.1W, i.e. a reduction of 30% in wasted heat.
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#38

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What is worrying me about this is:

Non of us would openly admit to a base response of 30hz, we would be all bravado like -3db 5hz phase on angle from 20hz blah blah testosterone willy waving banter.

But I now hear whole bass lines of music I never comprehended were there.

Must dust off the 301 and find my Trout Quintet. The bass line on that dissapears altogether on many systems.
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#39

Post by jack »

There'll be bigger problems than the diodes.

Get those electrolytics out of circuit and check their ESR and nominal value.

I'd wager good money its way past their bed-time...
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#40

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Paul Barker wrote:
But I didn't say it because I don't want you getting too big headed to fit into your open face pre 65 crash hat.
Thanks Paul. :oops:

Reminds me of a song that was popular many years ago when I went to a country and western pub that had singles evenings. It was "oh lord it's hard to be humble"

The last line was " oh lord it's hard to be humble, but I'm doing the best that I can." :lol: :lol: :lol: :lol: :lol:

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#41

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nickds1 wrote:There'll be bigger problems than the diodes.

Get those electrolytics out of circuit and check their ESR and nominal value.

I'd wager good money its way past their bed-time...
How do you check ESR?

Got some recommended replacements? Computer supply caps I suppose.
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#42

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pre65 wrote:
Paul Barker wrote:
But I didn't say it because I don't want you getting too big headed to fit into your open face pre 65 crash hat.
Thanks Paul. :oops:

Reminds me of a song that was popular many years ago when I went to a country and western pub that had singles evenings. It was "oh lord it's hard to be humble"

The last line was " oh lord it's hard to be humble, but I'm doing the best that I can." :lol: :lol: :lol: :lol: :lol:

Remember it well, it got into the hit parade. As did Tammi Wine ett "Sataind buy yoorre main honey an he'll stay allways with yer"
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#43

Post by jack »

Paul Barker wrote:How do you check ESR?

Got some recommended replacements? Computer supply caps I suppose.
With an ESR meter :)

PSU caps should have very low ESR - modern ones are in the low milli-ohm range. The ALS30A103DE063 I used in my Quad restoration have an ESR of just 17 milli-ohms.

I have a spare Dick Smith ESR meter (a good well known simple design - see http://www.flippers.com/esrktmtr.html) if you'd like to borrow it - I now use a Peak Electronics one...

There are loads of simple plans on the web that use 555 timers and a bit of other stuff to check ESR (its typically measured using AC at various frequencies depending on what the cap is being used for).

All electrolytics dry out over time - typically, after 20 years, its definitely time to look at how those babies are doing.

The small-signal electrolytics, so beloved of 1960s - 1980s designs, are also suspect - frankly, I'd just replace the lot and be done with it.

Modern caps are far more advanced, and thus smaller when compared with the originals, so a PSU cap may be only 50% of the size of the original and have a small fraction of the original ESR to boot, so you can put bigger PSU caps with lower ESR into the same space - note that if you do this you'll have to stay within the surge ratings of the bridge else it will exit the building...
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#44

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OK I am measuring 40v DC across these caps.

So Mundorf M-Lytic 10,000 µF 63v?
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#45

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OK I don't think I'll exceed the capacitance.

Right so I may have to replace every single 'lytic.

So you did this in the Quad's? Which caps did you go for?

Are you saying anything of same values in RS catalogue fits the bill? Or do we look for Mundorf or similar?
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