Retro and budget home hi fi

[First_rider_off]

Hi La Dodgy Vita,

Try the Discogs website https://www.discogs.com It is a fantastic source of used and new vinyl from all over the world. You will soon be able to judge the value of any vinyl that you have by reviewing what other people are selling for. I have bought dozens of fantastic second hand LPs from this site. Many of the sellers are specialist secondhand record shops and collectors. I would much prefer to buy off these people than Amazon. They have a very good system for grading the condition of records so you know exactly what you are buying.

[Nutbrook]

Recently re-capped all my old Quad (34, FM4, 303) & Meridian (M3) 1980’s kit. It will probably last another 30/40 years at least. (I’ll be over 100 years old by then!)

[Alf]

Hi, All,
I have been following this thread for a while but not sure if the bits I have will be of interest to anyone. I have tried them all recently and all are in working order. I have other bits not retested yet, cassette decks, Cd players, etc.
I haven’t included photos but if anyone shows interest, I will send the required pic to you or put on the forum. I hadn’t realised how much I had accumulated over the years!
Anyway, here is what I have:-
Luxman A312 Amp, Rotel RA 820Amp, Teac AV-H500D (110v but with 110-240v Xformer), Teac P1160D CD Player (240v), Sony SCD XE 597 CD Player, Panasonic DMR-EZ27 PVR, B & W DM speakers(pair), Gale 80w Sub woofer.
If anyone wants more details, let me know. No reasonable offer refused!

Alf

[Bettabuilda]

Great info Laurie and thank you! This might be a job in the New Year
I was gifted the first LEAK amp/tuner by a very kind gent on the forum, the same happened to him, been in service for fourty years, got moved ready for me to collect and bingo! Stopped working bought a second, working one, when I received it, again stopped working!
Will get them out of the rack and have a look when I get chance. TBH, I recollect bulging caps on one of them at least.
Barrie

[Roadie]

Just to add to the capacitor replacement discussion. The voltage rating shown on the capacitor is the maximum voltage it can handle. Their is no problem using a replacement with a higher rating, in fact it will give extra resilience. It’s like the speed rating on tyres. Also different manufacturers may have different values. For example 5,000uF or 4,700 uF. Interchanging these is highly unlikely to make any difference.

[Sammy]

Also, note on the blue capacitor in the photo has a date code of year 1978 wk 43. That is over 40 years old - time it was retired.

Most date codes follow the format YYWK and appear on most components - useful when trying to date when something was made.

[RichardFX]

Other features often written on modern big capacitors include
. ESR (Equivalent Series Resistance), and quoted at various frequencies. This should be as low as possible, and when high frequencies are quoted (eg 100KHz) then they are good for high speed switch-mode power supplies as well as in normal mains frequency rectifiers and audio coupling.
. Ripple Current Rating. Different to ESR. This hows how well the capacitor can get rid of heat for various currents, the higher the rating the better.
. Operating Temperature. Hard working caps in switchers will have a rating in excess of 85C, and best will be 105C. Not much chance of failure though bulges in a mere audio amp.

The manufacturers data sheets will say how long the cap will last when stressed at the maximums of these ratings. Not all use quite the same specifications, but for old fashioned linear (ie non-switching) audio they will be near enough.

[Martin_Young]

Oh, my, but the inside of that Quad 405 is familiar ground. I mended so many of those over the years. (Actually the BBC version “AM8/21” with an extra circuit board inside to run the two channels as the bass and high frequency drivers for an LS5/8 speaker. I think Richard might have mentioned them previously, somewhere further up the thread.)

Those big smoothing caps never give me any trouble, it was always smaller capacitors on the amplifier boards (or the BBC crossover board) which caused the problems, and the problems were usually a cascade of destroyed transistors. Mind you, that was 20-30 years ago, so I guess the big caps aren’t immortal after all.

Glad you got it going again. Lovely amplifiers.

[La_Dodgy_Vita]

I’ll take a look today.
Many thanks
Darryl

[Bettabuilda]

Afternoon everyone! Decided today to reconfigure the hifi rack in the lounge and while I’m at it, having a look at the two AD-6600 cassette decks. Beautiful (IMO) pieces of 70’s audio equipment.

First off, my original one, I’ve always felt it was running a bit ‘off’ in terms of playback speed. I have no equipment to calibrate the speed, just my own sense of what sounds right
There is a speed potentiometer on a small PCB, adjacent to the motor itself.

You can probably make out a very small hole in the board for access to the pot itself. Bought a set of plastic adjustment drivers to have a go at calibrating the speed.

The unit has a dedicated headphone socket which has a fixed output and I can listen to the music without an amp or speakers connected. Very handy when taking over the dining table as a work bench! it’s Mrs B’s day at the office today!
Anyway, put Supertramp’s Breakfast in America cassette album recorded on CRo2 tape and off I went! Trial and error has won out with same tracks played on Spotify and deck, matching them up to the best of my ability!
All sounds good now (at least to my ears). Easy fix in the end. Didn’t touch the calibration on the playback/record heads, that was a definite no no for me. Sounds good and will be better still through the amp and speakers once back in the rack.
On to its brother next. I bought this one as spares and repairs a while back, they’re reasonably rare (only produced in 1978) before being superceded by another revised model (AD-6700 IIRC)
Cosmetically as good if not better than my original one and I didn’t pay a lot for it.
It powers on, VU meters and cassette well all light up, peak meter displays for a second or so and then settles (same function as the other one) but no motor turning at all. New belts fitted all round when I got it, deoxit a plenty, all fuses checked, there are 6 in total, but no motor running.

On that little PCB, mentioned previously, I’ve measured 7 volts to the motor. Nothing there until pressing play, then 7 volts to motor but not turning. I’m wondering if the motor itself is Kaput
I’ve had the motor off the chassis, dismantled as far as I can, doesn’t ‘smell’ like its burnt out. Cleaned what I could get to, reassembled but still not spinning. Spindle moves but feels a little tight, certainly not free running but I wondered if that is normal for this little motor? It is 42 years old and perhaps past its useful life.
Barrie

[Bettabuilda]

Just to add, a bit more Internet searching and I believe the motor should see 12v ? Perhaps the supply side of things isn’t up to scratch?
Barrie

[Roadie]

With regards to the motor what is the voltage from the board on the working machine. If there is 12v then obviously you have a problem. Next thing to check is the voltage from the faulty machine board without the motor connected. If there is 12v then the motor possibly has a short circuit in the windings. This would explain why it feels a little tight and probably difficult to spin. A DC motor can also be used as a generator. Spin the shaft and you will get a voltage from it. If the windings have a partial short circuit it effectively puts a load on to the generator which makes it hard to turn.

As for setting up the speed a test tone tape and a frequency counter would be ideal. However commercially produced test tapes are expensive and I would guess you probably don’t have a frequency counter. All is not lost.

Assuming you have at least one cassette deck which you know to be good and running at correct speed then use it to record a 1KHz test tone. Where might you get a 1KHz test tone I hear you ask. Google and You Tube are your friend.

1kHz Sine Wave Test Tone Signal

Now simply play this on the deck that needs the speed adjusting and adjust it until the tone is at 1KHz with your frequency counter. What frequency counter they all cried. Grab your phone, go to the app store and search for ‘audio frequency counter’ and there are plenty to choose from. I just tried the Keuwlsoft one and it measured the You Tube tone at between 999.5 and 1,000.5 Hz

[Bettabuilda]

Hi Paul, the test tone app and generator looks a good idea
I’ve tidied everything up for today (read Mrs B may be home soon!) So will have to revisit on another day! I have an AIWA AF-3060 Casseiver from the same era with a working motor but other issues ( more of a decorative piece than a functional unit) might have a look in there and see if the motor is the same? Could swap that out if it is. Who needs two cassette decks anyway
Barrie

[RichardFX]

@Bettabuilda

I’m wondering if the motor itself is Kaput

Always possible.

With an external speed controller like your Aiwa (instead of built-in eg PC fans with two or three wires) it also depends on what kind of DC motor it is. Usually they are either brush, or stepper.

The steppers have a slight cogging action if you turn them with no power, but they also have more than two wires, usually four or five. These are usually only found on more expensive machines with digital speed controllers. Steppers have a permanent magnet, no brushes, and three or four windings, which should be of equal resistance, three windings could be delta or star (three or four wires), four windings usually five wires and star.

The brush motor can wear out the brushes, or burn the commutator, or seize the sintered graphite-phosphor-bronze-bush bearings when someone mistakenly lubricates them. If it is easily dismantled then the brushes might be accessible, but take care not to disturb the magnetic flux paths where you might lose magnetism (think of ‘keepers’ on speakers and voice coils).
Measure the resistance through the brush motor (with correct polarity from test meter) while slowly turning it, if it is consistent with regular variations as you go through the segments on the commutator, then brushes and commutator are probably OK.

If the circuit board is controlling the motor, then from a 12V supply to the board I would expect the motor to normally run on about half that supply voltage to allow for more torque when the tape is longer and heavier (eg 120min vs 30min, more friction inside the cassette at the ends) etc.
So if you load the motor expect to see volts across it raised when the board compensates.
On many of these machines the board sees the commutator switching between segments (brief fluctuations in the current supplied) and counts these little pulses to know how fast the motor is turning, hence apply more or less power to control the speed against a reference of some kind - the potentiometer in your machine.

Have fun!

[Countryboy]

Great posts gentlemen, even if I haven’t a clue as to what you’re saying
Just one question, is the 1Kz SINUS tone supposed to clear ones blocked sinuses?
Whatever, it certainly sets my tinnitus off!

[Bettabuilda]

Thanks Richard, there are actually 4 wires from the motor, 2 x yellow, a black and an orange. I checked the black and orange ( being thicker gauge) thats where I got the 7 volts from on the board. Only gave a voltage when play key was pressed with a cassette in place, although no life from the motor. Interestingly, the motor, when manually spun, feels like its going round in segments as you said, not free spinning. The original machine has had a thorough testing this afternoon, enjoyed listening to tapes!
Barrie

[AndyGadget]

I started my working life back in the early '80s as an electronic test technician working for a company which manufactured dot matrix printers. Automatic component placement was only just coming in and a lot of the PCB assembly and all the larger components were placed or wired by hand. Printers would be assembled and then burnt in for 12 hours on racks. My job at the time was to diagnose and repair the ones which failed.
Once I’d been in the job for a while I could diagnose most major faults by smell. A blow-up of the pin driver darlingtons smelled quite different to the line feed transistors. A reversed 50V 42000uF cap would explode with sweet smelling white smoke and leave cardboard fluff all over the inside of the printer case. A reversed 100V 4700uF cap would blow out a pressure relief bung and squirt a yellow fluorescent fluid all over the inside and quite a bit through side vents of the printer. Tantalum capacitors went with a crack, a puff of orange smoke and a vile pong all of their own. Occasionally there was a total bus burnout (which I discovered the reason for when I later moved into design) popping around a dozen chips on the data bus. Quality control was not the best there.

[RichardFX]

@Bettabuilda

4 wires from the motor, 2 x yellow, a black and an orange

Chances are the Black and Orange are motor current, and the two yellow could be either tachometer (most likely) or slave inputs (unlikely). Looking at that simple control board my guess is tacho.

Check with your voltmeter for an AC signal (maybe half a volt?) coming out of the motor on the yellows when you spin it by hand, first when powered, and again when not powered.

If tacho produces output in both instances it does not need power and the power wires to the motor have a bad connection inside it, maybe even the brushes. Nothing lost by opening it and having a look.

If it produces output only when powered, and not when not powered then the motor needs a good seeing to, again probably brushes. I doubt the motor ever got hot enough to produce a terminal dark brown smell.

[Bettabuilda]

Thank you Richard, will have a go next time Mrs B has to go into work!
Barrie

[Bettabuilda]

Always nice to have several things on the go!
This came in the post today.

Loving the handwritten names and addresses I’ve mentioned before, H J Leak were only about 8 miles from me when they were still manufacturing.
Plenty of info in the service manual to assist in getting the LEAK DELTA 75’s back from the dead!

More than likely, I’ll forward this with the amps when the hifi shop I deal with, reopens as things start to get better. It may be of use in effecting the repairs.
Barrie