Dynatron SRX26-30 range Music Centre Info

[Techman]

That's a thought, David.

The mat and the disc do not come off the TT like they do on many other models.

Like you say, though, that screw is a thought and I did notice it, but thought I'd leave it for the moment - I'll try a gentle 'tap' tomorrow and then go for the screw.

I nearly forgot - just to answer a post by RGD Dennis on the 2nd December, post 30 on the previous page as regards the older large Dynatron grams. If it's the same one that I saw (and I don't look a great deal, so may have missed a more recent one - a tatty one did go for the amp a week or two back), it was a year ago virtually to the week that a K129 Ether Conqueror the same as the one that I've got was sold. It was actually sold for £3,300 and it looks like it was another one that went across to Australia.

It's with thanks to Dennis that I now have a nice period deck back in my Dynatron K129. I had a radio that Dennis had been looking for for many years, so we did a straight swap. We kept in touch and Dennis sent me pictures of the radio when it was fully restored. I must update the threads on both the radio and the radiogram as Dennis hasn't seen any pictures of the Dynatron with the deck installed yet. When I say that Dennis sent me pictures, these were 'proper' pictures that came through the post in a package - none of this modern digital, electronic nonsense from Dennis

[Diabolical Artificer]

It's funny how some threads take on a life of their own. I didn't buy the Dynatron in the end. It was only a tenner, but my bedroom is getting a bit full; I'm storing all delicate electronics there over the winter. The shed/workshop is too cold and damp.

I'm glad all you chaps managed to get sorted out.

Andy.

[jamesperrett]

Originally Posted by Techman

It's not the same as the G102 which doesn't seem to have been very 'popular' & there is no information that I can find about it on the net anywhere - not even the drive belt is listed by any of the people that do belts, but I'm sure it'll match up with something - when I get it off.

The G101 and G102 were fairly popular budget belt drive decks - possibly the cheapest belt drive decks you could buy at the time although BSR got into that market a few years after they were introduced. They were designed and made by Goldring themselves. I'm not sure whether Goldring were still reselling the Lenco decks when these were around but they were priced lower than the Lenco decks were.

When I replaced the belt on mine I just bought a selection of likely looking belts from CPC and used the one that seemed to fit the best. It worked fine for the few years I owned the unit.

James.

[Paul_RK]

Originally Posted by dalgwcobl

Apart from a period under EK Cole ownership in the late fifties when a few radiograms used Ekco chassis, ALL Dynatron audio models used their own in-house designed chassis, right up to the seventies.

I think the Ekco chassis would be early '60s, rather than late '50s while the Hacker brothers were still around - I've an Ekco radiogram from about '62 whose chassis I've seen badged as Dynatron. Fairly sure about Pye's HFS30T amplifier having been used a tad later too, the control layout is distinctive (five evenly spaced knobs in a row then four slider switches one above the other) and is replicated exactly in some mid-'60s Dynatron 'grams.

Paul

[Techman]

Andy - I think it's down to this thread just having the perfect title, probably more by accident more than anything else. Everything being discussed here is basically 'on topic' & can apply to 'all' the variations of these Dynatron units, so the thread will probably be able to go on & on & on - as you can see, it's very popular by the amount of views it's had. BTW, I see you're virtually just down the road from me, so to speak.

James - yes, what I meant to say was that the G102 was very popular at the time, as you say, but it seems that when you do a search for anything written about it now, that it's rather not so popular with the 'HI-FI' folk. I actually think that it's not too bad a deck & does the job ok, but would have been a lot better with a full size turntable. You're right about the belt - I think I'll be able to match it with something. I could see part of it from underneath when I had the bottom off the case & it seems to be a fairly standard width. Would you agree that the turntable should just lift off with a sharp tap in the middle on the spindle?

[jamesperrett]

It is probably 10 years or more since I replaced the belt on the one I had so I wouldn't rely on my memory but that would be the first thing I would try. I would also check under the turntable mat for a circlip but I have a vague memory that after I removed the mat on mine I realised that I hadn't needed to.

James.

[Graham-R]

Originally Posted by Techman

I took the bottom off my (baby) Dynatron yesterday to have a quick look inside for the first time & it has quite a nice little amp unit with 'proper' components as shown in the picture below.

Techman

I have just stuffed all that into a tiny little box, soon be even more stuffed when I add switching + pre-amp etc to turn it into an integrated.....

It actually sounds pretty good, and is stone cold after an hours pounding with loud rock music !

Graham

[Techman]

Thanks for that, James.

The mat & the disc in the middle are stuck fast & look to be original with no means of levering them off so I'll be going for the smack on the spindle while pulling the TT upwards when I get round to it. It'll likely be the original belt from 1976 & the turntable will be as it was fitted on at the factory so that'll be the reason that it's a very tight fit. It's still working ok due to the pickup being able to track at such a light weight, it's just that it slips if I try to use the dustbug - not at the same time as I'm playing the record, I hasten to add.

Graham - I have to admit that it was only when I was looking again at those files that Gezza had posted, that I realised that what is shown is the actual circuit of the amp unit that is in mine, too. I hadn't actually appreciated that all these units seem to be using the same amplifier until I was looking at the circuit again. These really are a good 'punchy' amplifier with plenty of power & a very good frequency response. Ok, so it's not valves & not PX4s & it may only be the Dynatron badge when these were made, Philips, weren't they, but mine certainly gives a really good account of itself. It's good to see the proper output transistors on heatsinks rather than those usual sealed black modules that you usually find.

Andy - You'll be starting to wish you'd bought that one for a tenner if we go on much more about how good they are

[Graham-R]

Finally finished the PA stage of the build, one thing to note is that the amp produces about +12volts dc on the output if it is not terminated with a speaker or dummy load, It does not seem to damage the o/p stage, at least in the short term. This caused a bit of head scratching when I connected internal speaker protection module as this one did not have the resistors fitted for single rail power supplies, it simply would not switch over to normal operation as dc was permanently present.

A good little amp for the workshop - it is not pretty enough for the lounge, it will be even less so when I have finished putting some input RCA and 3.5mm jack sockets on the front....

The image attached below is the replacement receiver I am building to go in the Dynatron cabinet - plenty to do yet.

[Graham-R]

Update, the SRX30 amp turns out to be really good - currently using it with a Velleman valve pre-amp, some nondescript Pioneer speakers and an ipod. Hardly top stuff but it makes great music.

Surprised ? I should bally well say so, I am taking it with me (and a Crimson Elektrik pre-amp) when I next work away from home.....

[dalgwcobl]

Just to reiterate, Dynatron SRX series chassis were entirely Dynatron designed and, although the factory in King's Lynn became a wholly owned subsidiary of Philips, the chassis were NOT of Philips origins. Some Mullard (and other) tuner IF modules were used, but the overall tuner and amplifier design was unique to Dynatron.
The Goldring G101 and later G102 turntable units were developed by Goldring and UK built, for Dynatron, although Goldring also sold them separately (badged Goldring) in plinths as stand-alone units.
The G101 was chosen because of its superior mechanical performance (ie wow and flutter and rumble) to the Garrard SP25 of the day. The original G101 had the speed change lever in the right hand side panel along with the on/off switch. The drive belt was quite thin and of circular cross-section. However, dealers reported that, whilst it performed very well sonically, customers complained that it had too little torque to enable a Dust Bug to be used without slowing it down. The result was the G102, with a wider, flat section belt and the speed change a large rocker 'switch' mounted on the bottom left hand side of the deck. The torque was improved so a Dust Bug would work. If it won't work by now, the belt needs changing. The trade-off of using the tougher belt was that more motor noise was transmitted to the turntable, with consequently poorer mechanical noise figures. When selecting a replacement belt, it is important to find one that is not too tight a fit.
I can't remember the exact reason why, but the Goldring units were replaced after only a couple of year's production, by the Garrard SP25 - the Mk3, I think. This necessitated a redesign of many of the cabinets as the SP25 had a narrower, deeper-shaped deck (the G101/102 was a unique shape) and had a taller profile. The change took place for 1975 model year, with many existing model numbers increasing by a factor of 10 - eg HFC59 became HFC69 - and the chassis numbers changed from SRX29 and SRX30 to '1275' and '1375'.
Incidentally, Goldring were still importing Lenco GL-series turntables at the time, badged as Goldring-Lenco.
This may help to unravel the different models, as Dynatron produced a large range.

[Diabolical Artificer]

Techman,I am wondering now if I missed a good un. Especially after what the last poster said. It did look quite nice with a well built redwood cabinet etc,it had the original speakers too. Oh well,ce la vie,Andy.

[Graham-R]

dalgwcobl (what does that mean !)

Further to your threatise on decks fitted to Dynatron models, the one I bought was fitted with a Garrard Zero 100 SB turntable - the one with the parallel tracking arm, interesting concept. Since replaced with a Sugden BD1.

Some info here:

http://www.tnt-audio.com/sorgenti/garrarde.html

Graham

[dalgwcobl]

Dalgwcobl means a computer-generated e-bay name. It just sort of stuck.

The Garrard Zero-100 SB was fitted to the Dynatron Dorchester Music Centre model described earlier, and used a pick arm with a parallelogram linkage which was supposed to maintain the correct alignment of the cartridge as it traversed the record. This was OK if all the linkages didn't wear, and must have increased the friction in the arm movement. Otherwise, it was a good performer.
The earlier rim-drive Zero 100 was a full changer with the same arm, and had a fine speed adjustment and neon-illuminated strobe bands on the edge of the turntable. I seem to remember that it used the 'umbrella' type changer spindle as on the earlier Lab80. A Zero 100 was fitted to the special system installed in Balmoral. When we later updated the system, the Zero 100 was replaced by a Philips single-play unit. The Zero 100, which by then was surplus to requirements, found its way into my system for some years. For the life of me, I can't remember what happened to it. It must be in the loft somewhere.

[dalgwcobl]

Originally Posted by Paul_RK

I think the Ekco chassis would be early '60s, rather than late '50s while the Hacker brothers were still around

Fairly sure about Pye's HFS30T amplifier having been used a tad later too, the control layout is distinctive (five evenly spaced knobs in a row then four slider switches one above the other) and is replicated exactly in some mid-'60s Dynatron 'grams.

Actually, the Dynatron 12/10 and 16/24 chassis only replicated the Pye HFS30 amplifier controls layout and the tuners were unique to Dynatron with three wavebands rather than the Pye's FM only. The chassis was, in fact, entirely Dynatron. (They had just inherited what was left of Pye's Hifi division, but didn't use any of the Pye chassis; the trade conditions determined that Dynatron had to produce a 'transistorised' chassis to meet public demand). It's a long time ago, and I don't have any info in the archives, but I remember the 12/10 was the smaller-output chassis producing 5 watts RMS/channel fitted to the 'cheaper' models, and the 16/24 used a larger power supply to produce 12 watts RMS/channel, fitted to the top-end models - the big 'grams in the big cabinets. In those days, large speaker drivers in big open-baffle or bass-reflex cabinets would make a lot of noise with 5 watts!

[Paul_RK]

Ah, that's interesting: thanks for the correction. I have an HFS30T and had noted the identical layout and jumped to the obvious and mistaken conclusion from occasionally noticing the Dynatron 'grams for sale. With there being so many examples of badge engineering where considerable pains are employed in disguising that items sold under different brands are more or less identical technically, it had hardly occurred to me at all that the Pye/Dynatron likeness there might be only superficial.

Paul

[Graham-R]

Originally Posted by dalgwcobl

The Garrard Zero-100 SB was fitted to the Dynatron Dorchester Music Centre model described earlier, and used a pick arm with a parallelogram linkage which was supposed to maintain the correct alignment of the cartridge as it traversed the record.

The info I have says that the Dorchester was fitted with a Lenco GL78 (as standard ?), perhaps the Zero100 was fitted as an optional extra ?

The parallel arm on my example didn't seem to have too much friction, of greater concern was a feeling that it was not quite as rigid as it could be. I never actually played any records on it so cannot comment on whether it was any good or not.

[dalgwcobl]

As with many of the Dynatron models in the 60s-70s, there were several versions of each model. It all got terribly complicated in the mid-70s, as mentioned earlier regarding the G101/102 turntable units.

There were several versions of the Dorchester Music Centre, all of which were fitted to the same style of cabinet:

The earlier HFC103 used the Goldring-Lenco GL75, with Goldring G800 cartridge and the '100 series' chassis with 45 watts RMS/channel, pre-set FM tuner and the Philips N2505/10 cassette unit (no DNL).

Later HFC103s used the Goldring-Lenco GL78, with Shure M55E cartridge and Philips N2505/51 DNL cassette deck.

The HFC104 used the GL78/M55E and the '100 series' chassis with 45 watts RMS/channel, three waveband tuner with manual tuning and the Philips N2505/51.

The HFC71 was fitted with the SRX30 chassis (15 watts RMS/channel) and Garrard Zero100-SB with Shure M55E cartridge, plus Philips N2505/51 DNL cassette deck.

Looking back at old brochures and service manuals, it really did get confusing as to the number of models, chassis, cabinet styles and finishes and record decks, not to mention two Dynatron-branded cassette decks, one with DNL made by Funai in Japan, and a later Dolby B-equipped deck, model CD780, also sourced from Japan.

In the late 70s, the 100 series was replaced by the SRX60 chassis which was teamed up with a Philips 22GC037/59 single-player turntable with GP401 Mk2 cartridge and the CD780 Dolby cassette deck.

There was a huge number of chassis and cabinet variants throughout the 60s and 70s. The best source of information would be the service manual/data sheet produced for each chassis type, which would list the models it was fitted to and turntables, cartridge/stylus and tape deck used. I wrote many of those manuals, but it's difficult to remember too much detail thirty-five years later!

If anyone REALLY wants a breakdown of the range in the 60s and 70s, I can probably cobble together a chart for reference. There were really only a few basic chassis types, with umpteen variations on the theme!

[Chiltern]

Re the Goldring 102 deck. These were also available as a constructional kit CK2.

I can recall buying one of these kits from one of the suppliers on the Tottenham Court Rd back in the 70's for, I think ,around a tenner. I'm sure that there was nothing as sophisiticated as a taper to hold the platter. I recall that there is a circlip under the mat, the mat came with adhesive already applied, with a protective film to be peeled off before fixing.

A couple a years ago I bought one of these from a 'car boot', unfortunately the motor was US, however I did get the mat off with the aid of a very carefully used hair dryer. The mat was recycled onto a Garrard autochanger.

Alan