Restoration of HMV STEREO 666 (1976)

[anirban420]

Way back in 1976, my father was then 21 years old boy. He owned a HMV STEREO 666 that time. HMV and PHILIPS record players were dominating the market that time. Mostly the budget players were highest selling. HMV STEREO 666 was also a budget player of that time. Its price was Rs. 1768/- only that time. Though the player was an entry level model, it became a member of our family gradually, not from a audiophile point-of-view, but from an emotional value. This player was used in many social occasions in our home, as well as my father used to play it in puja pandals arranged by him and with his friends. I can remember that I used to sit in front the player starring at the rotating large black discs and gradually moving tone arm from the periphery to the center, these things usually made me astonished. Time goes on, and new things replace the older one. Its now the era of listening music in mobile phone, peoples including me and my family members have forgotten listing music on those engraved black disc. Suddenly I found the player in my home, it was packed in a corner of my house. I feel nostalgic by seeing it after a long long time. The player is now 40 years old. I switched it on, It sounds creepy. Sound was coming when I connected my mobile in AUX port, but something is missing, a serious lack of bass i noticed. Also, the turntable part was not moving, however, the motor was revolving. Stylus was missing. And I can remember the original pickup cartridge was broken in my childhood. i replaced it with a non-HMV cartridge which needed a strange looking stylus.

I was attacked by nostalgia fever. Planned to restore the player. I know it sounds average, and this is not a cost-worthy project. But those childhood memories attached with the player have great importance to me, and this the inspiration of restoring the oldie....

So, this is the story of restoration of my sweet old HMV STEREO 666.

 

[anirban420]

The construction of the player is pretty basic. The turntable is a common HMV turntable which was widely used in 70's-80's in most HMV budget players. Its a manual operated turntable which uses a AC motor which transfer its speed to platter via a speed-pulley+idler combo. It is a 4-speed player. The pulley is a stepped one, one step for each speed.

Its electronics is made around two 10-watt amplifier, one for each channel, and a level monitoring circuit which drives two 6-volt bulbs, one for each channel, for sound level monitoring. The heart of the amplifier is made by two complementary Germanium pair PT4 and PT6 operating in Class AB push-pull mode, driven by germanium Class A driver AC188. Germanium transistors were a popular choice that time. An this part is the only unusual thing now-a-days. Rest of the amplifier is very common. A RIAA equalized per-amplifier designed for ceramic cartridge, a Baxandrell based tone-control circuit consisting of BASS and TREBLE output of which connects to the driver stage of the amplifier via a Class A Voltage Amplification stage made by BC 148A.

Pretty basic... is not it?

I will post the circuit diagram, just give me some time to make it.

I will discuss about the Level-Monitoring circuit later, because its quiet unusual one

 

[anirban420]

The player was not that much dirty when i opened it. Firstly I have cleaned the inside with mini vacuum cleaner. then started finding the problem in circuitry. Checked every Germanium ones, PT4, PT6, AC188 showed great reading during hfe testing. PT4 and PT6 measured above 300 hfe and AC188 measured around 150. such a high gain!!! And thank god that these Germanium were OK, because finding a germanium transistor is not a easy job specially its very hard Kolkata. And there is no easy Silicon replacement of those transistors. So I planned to proceed in a conventional way, changing the caps at first.

when I checked the resistors, I found many were opened or showing abnormal values even when checked outside the circuit. two-three resistors were cracked and already broke during de-soldering. For this confusing scenario of resistors, I changed my plant to replace every components of the circuit with fresh ones except those Germanium ones. BC548A is not available anymore here, and the super availability of high gain BC548B restricts the use of the "A" version too. I also changed every "A" to "B", although few of the "A" were also changed in the past.

The inside picture which I am giving here was taken after some stage of disassembling, sorry for not providing the "freshly opened" pictures. Also I am attaching a picture of the old board, however some original components were already replaced in past. And not a single original coupling cap was present

 

[aks07]

This should turn out to be great thread.
Eagerly looking forward to updates.
Based on my experience those blue Philips electrolytes should still be ok. I would retain them if so.
Good that the BEL PT4/PT6 are alive. These are very delicate beauties and used to go puffftt at the slightest provocation.

 

[anirban420]

Based on my experience those blue Philips electrolytes should still be ok. I would retain them if so.

Thanks aks07 for your reply and also for showing interest in my post. I have changed those blue caps (all of them) with KELTRON caps. These caps were 40 years old. Generally electrolyte capacitor do not last more than 30 years if properly maintained and proper voltage applied. From this point of view I changed those all. Don't know whether those Blue caps were PHILIPS or not, no "PHILIPS" marking was present on those caps. Only a "Y" is marked on those caps, picture attached. BDW, I have seen proper "PHILIPS" marked capacitor in the past, however those were radial caps.

 

[anirban420]

I have changed all the components of the two amplifier boards, obviously, Germanium transistors were kept intact. However, there was some unusual components present in the original circuit which are no longer available now. These are unusual valued electrolyte caps, 50uF, 25uF. Since these values are hard to find, I changed them with 47uF and 22uF respectively. Originally Mullard-Mustard capacitors (Picture attached) were used in RIAA equalization circuitry. I changed those for three reasons, one of the cap was cracked and eventually broke during de-soldering, secondly all of them was of 10% tolerance, thirdly these type of caps were not found in Kolkata. So I replaced all of them with Polypropylene Caps (picture attached) having 5% tolerance.

 

[anirban420]

There were another two unusual things in the circuit. Baxandrell Network was mounted on BASS TREBLE pot. And secondly, the treble capacitor was a Polystyrene 600pF. Firstly the value is unusual, secondly polystyrene caps are no more available here in Kolkata. The circuit used four of such caps, two of them were previously replaced by polyester caps by some mechanic. Those alive two Polystyrenes were very accurate when measured, one of them show 603pF and the other showed 604pF in multimeter. I kept those two as TREBLE caps.

I am attaching the picture of newly constructed Baxandrel Network mounted in the pots.

Another unusual thing. The original circuit used lots and lots and lots of shielded wires for connecting the Tone control pots to the main board. all these created a mess, whenever you are going to do some work on the board, any of these wire will be worn out. I replaced all the wires with a single 4+1 shielded wire (as seen in the picture) to avoid circuit mess up and unnecessary frustration during work.

 

[anirban420]

Proudly presenting the all component replaced "fresh" circuit board (Picture Attached). I have given a trial run of this circuit attaching my mobile. I have connected its original Box which have a single full range 6" 4ohms transducer, (frequency response is probably in the range of 100-12,000 Hz when checked by EAR:lol:, merely emphasized on a wide mid-range frequency). Old songs played suuuuuppppeeeeerrrrrbbbbbb in this circuit:yahoo::yahoo::clapping:hyeah:hyeah:. Such a sweet presence of both male and female voice. lows of the 100-250Hz range was accuratle reproduced. Highs of 4-6kHz range sweet and crisp, however having a bit oldies tonal quality and color. Its a perfect companion for listening to the old musical beauties of 60's-70's era. But the machine did not performed well when played current songs, especially Hindi ones which have a wide frequency range. Deep lows and super highs are emphasized now a days, and these are not easily handled by those poor Germaniums :sad:. Sound were over emphasized on the midrange. Not at all an ideal thing for easy listening of all types of music. But telling again, for old tracks its superb.....

 

[reubensm]

What a beautiful thread, really so nostalgic. Well done. Looking forward to seeing the whole turntable up and working. HMVs truly have a special place in the homes and hearts of many Indians of our era. Great stuff. The PT4/PT6 pair and similarly, the AD161/AD162 pair was quite commonly used in low power amps of those times. Sounded great.

 

[reubensm]

I forgot to mention, when restoring the turntable part of the project, try to lay your hands on an original HMV stereo cart. If not available, look out for an EEI CS2000 stereo ceramic cart. These had their own sound signature when wired to these old circuits. Believe me, when listening to vinyl, even the newer bollywood releases will sound good if you use one of these carts with your little amplifier. These were early designs and were conceived keeping in mind focus on a broader mid range with restricted lows and slightly rolled off highs.

 

[anirban420]

Thanks for the input reubensm. I was just w8ng for you comment . I have found the original HMV cart in second hand shop here. Costs 500/- bucks for the second hand ones. If I tell them to give a specific model number, they will stare me strangly hyeah:. Actualy they will provide me the cartridge removing from any old machine. My goal is to take the cartridge from any existing 666 or 1010 machine. Dont what is there in my luck. Anyway, can you provide any info about how to get the EEI CS2000? I feel curious about the cart

 

[reubensm]

Thanks for the input reubensm. I was just w8ng for you comment . I have found the original HMV cart in second hand shop here. Costs 500/- bucks for the second hand ones. If I tell them to give a specific model number, they will stare me strangly hyeah:. Actualy they will provide me the cartridge removing from any old machine. My goal is to take the cartridge from any existing 666 or 1010 machine. Dont what is there in my luck. Anyway, can you provide any info about how to get the EEI CS2000? I feel curious about the cart

EEI CS2000 was a stereo cart commonly available in India, in the 1970s and early 1980s. I have done a lot of listening hours on this cart and must say that it is pretty good. To my ears, it sounded like the Sonotone 8T which is a very sort after ceramic cart. I used one in the very recent past on a Garrard RC210 changer with great results but that changer is not with me anymore. HMV used a standard Mono-type and Stereo-type cart in all their Mono and Stereo players. Hence the same ceramic cart was used on the 666, 1010, 1212, 1515, etc. The same mono carts were used on the calypso, fiesta, popular, etc. HMV ceramic cartridges are not bad idea. I must mention though that the replacement flip stylus for EEI and HMV carts look identical but are not interchangeable. As a 3 year old, I can still remember my dad playing records on his HMV Mono Calypso with a huge horn loaded speaker. I still remember that it sounded like what my Dad used to refer to as "theatre-like-sound", back in the day.

 

[anirban420]

HMV used a standard Mono-type and Stereo-type cart in all their Mono and Stereo players. Hence the same ceramic cart was used on the 666, 1010, 1212, 1515, etc. The same mono carts were used on the calypso, fiesta, popular, etc. HMV ceramic cartridges are not bad idea.

So, I can go for a used HMV ceramic cartidge for my player? What say? CS2000 is not available atm

 

[anirban420]

I must mention though that the replacement flip stylus for EEI and HMV carts look identical but are not interchangeable.

My dad used EEI MX20 stylus in his days. I still have those used cartidges with their original packing. But their life has ended up due to overuse. Should I post their pictures so that u have a look at them and pass your valuable and experienced comment for me?

Our Kolkatan second hand record shop owner have those EEI MX20 in unopened sealed pack condition. Price is too high, each costs 300/- bucks now. I have planned to go for those stylus. Beside those, they can provide me original HMV STYLUS but in used condition for Rs 100/- each. What is your opinion in this?

 

[reubensm]

So, I can go for a used HMV ceramic cartidge for my player? What say? CS2000 is not available atm

Yes, a used HMV stereo cart will work very well but ensure it is in good condition before purchase. If the cart was used by someone who was not careful while replacing the stylus, physical damage could result in poor or no performance. The key parts to look out for are (1) the pressure plate which holds the base of the stylus body and t(2) he rubber inverted "U" that supports the stylus cantilever. If this rubber support is damaged or improperly aligned, the cart is not likely to work properly. Even if it works in damaged state, you are likely to face channel imbalance issues (for stereo), tracking and distortion related issues.

 

[reubensm]

My dad used EEI MX20 stylus in his days. I still have those used cartidges with their original packing. But their life has ended up due to overuse. Should I post their pictures so that u have a look at them and pass your valuable and experienced comment for me?

Our Kolkatan second hand record shop owner have those EEI MX20 in unopened sealed pack condition. Price is too high, each costs 300/- bucks now. I have planned to go for those stylus. Beside those, they can provide me original HMV STYLUS but in used condition for Rs 100/- each. What is your opinion in this?

Yes the MX20 stylus was compatible with EEI carts, if you dad used them then they would have been compatible with the HMVs as well. The "high" price of Rs.300/- per "new" stylus is a price worth paying for the assurance of not damaging your valuable records. Using a worn stylus can cause serious irreversible damage to your records. It is hard to judge stylus condition from photographs unless you use a microscope. If you check on line, there are numerous resources that will guide you on how to ascertain whether a stylus is in good condition or not. Using an old stylus is ok if you are sure of its usage history or if you can get it assessed by someone with an expert eye.

 

[anirban420]

I have planned to go tomorrow for the cartridge and stylus. Lets see what is in my luck. And I will keep the points told by reubensm during the cartidge purchase. I post further update tomorrow.

 

[anirban420]

Hi folks,

Before going to post further updates about the restoration, I want to share awesome experiences of getting my desired cartridge and stylus that happened in Chandni Chawk. I knew that sealed pack old stock stylus is available here. But the price is 300/- bucks per piece. So I wanted to justify the price. Here are now 4 record dealers present in Chandni-Welighton area. I asked everyone, except the seller who have it. Everybody starred at me very astonishingly thinking that who is this mad guy expecting a sealed pack 'needle' in the year 2016. One of them laughed at me. And one challenged me if I can show him a sealed pack stylus then he can sell me some records in a discounted rate. I immediately went to shop where stylus was available, bought two of them and within 15 minutes show it to the seller who challenged me. He was very much surprised to see those thing (uska mukhda dekhne ka layak tha us samay hyeah:hyeah::lol::lol. Anyway, I bought 7 Bengali records (5 LPs and 2 78rpm Shellacs) at the rate of 70/- each on an average. Price of Bengali LP and 78's are in the range of 80-200 bucks now a days. I was very happy in the deal . Here are the pictures of the records. The LP which id second from the left, Blue-Green cover, named Hits of Manna Dey, printed in English is the First ever LP album of Manna Dey.

Please ignore the next three posts....

 

[anirban420]

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[anirban420]

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