Dynatron Cordova TRP-1 R2R Checkout

[DMcMahon]

Very early 1960's 3 speed, 2 track, valve mono reel to reel using the Collaro Studio tape deck.

Brought recently from Charity Superstore. Rather grubby condition but should clean up reasonably well.

2 of its red rubber feet are missing and the lid catch parts on the case are missing. After a bit of a struggle removed the complete chassis out of the wooden case (was a very tight fit) a lot of cobwebs inside but otherwise looks untouched.

All valves are present, EF86, ECC83, ECL82 and EM84, bridge rectifier is a metal selenium rectifier.

A visual inspection revealed 2 initial faults, a shot rubber resilient mount on the capstan motor as per this Thread -

https://www.vintage-radio.net/forum/...d.php?t=203988


and a blown 2uF electrolytic C28 (a green TCC Micromite) for the ECL82 screen decoupling.

Was not planning to replace all the paper capacitors but from testing them, they are all bad (a mixture of black Wima and sticky plastic covered TCC Metalmite), so will renew, also a second electrolytic that is open circuit capacitance wise (red/yellow/black 25uF Plessey) C26 cathode bypass for the ECL82.

The black wires going to one side of the loudspeaker (an EMI 10" eliptical) had broken off, they were a little push fit connector, could not get it soldered back on and still have good push fit connection, so soldered the 2 wires direct to the loudspeaker connection.

David

[DMcMahon]

As shown on the first photo above the Collaro Studio deck has the red button Record interlock on the Start key. Mechanically have not yet worked out how this actually provides the interlock. The Record interlock button is not present on my Challenge R2R so presumably the Studio deck in the Challenge is an earlier model.

While taking the capstan motor bush from the Challenge to replace the bad bush in the Cordovo capstan motor noticed that the Speed Control Lever on the Challenge is upside down compared to the Cordova, looking at the Studio manual this confirms that the Speed Control Lever in the Challenge machine is indeed mounted upside down, I must remember this when I get back to working on the Challenge.

David

[ben]

That chassis looks a delight to work on, David! A nice change from the likes of the playmaster which was popular around that time. As you have found, most those caps are change- on- sight parts and I wouldn't be surprised if some resistors have drifted also.

[Welsh Anorak]

Like Ben I was expecting to see the usual 'rat's nest' of wiring below decks, but what a surprise! A few capacitors and I'm sure it'll be booming out again.

I think the odd red interlock was a later addition - my Elizabethan has one, but earlier decks don't.

[DMcMahon]

Yes one of the best I have come across for access and space, good also to be able to get the complete chassis out and not have to run extension cables to speaker (that is often mounted in the case).

Even though it looks pretty tidy it still has the UK look of homemade/Heath Robinson somewhat.

David

[bileaflet_valve]

On my Collaro Studio Deck, the red slider does not do anything mechanical, but operates a switch. As far as I remember, it works a change-over switch intended to apply the erase current to the erase head if operated, or to a dummy load resistor (substituting for the erase head) if not operated.

Hope this helps,
Les.

[ben]

Superimpose feature by the sound of it, Les

[DMcMahon]

Not yet checked it out fully but am still confused how the red slider button provides the Record interlock.

On the amplifier chassis is a 4 position rotary switch Record/Play/Amplify/Superimpose, I was initially thinking that somehow the red slider mechanically interlocked the rotary switch from being turned to Record unless the slider was pushed down, but see now that is not the case.

So now think that the slider must somehow electrically make/break the Record setting of the rotary switch at the amplifier. I can that when the Record slider is pushed to its down position that a lever moves down, but I cannot see (without stripping the Tape Deck) what the lever actuates.

Needs more investigation.

David

[Nickthedentist]

Originally Posted by Welsh Anorak

Like Ben I was expecting to see the usual 'rat's nest' of wiring below decks, but what a surprise!

Yes, it's beautiful. But then even by this stage, Dynatron products were a cut above the rest, both inside and out.

[Welsh Anorak]

Of course you need to remember the Collaro was a cheap (for a three motor design) bought in deck and the feature might not have been used in all applications.

Some lower end products that used it even ignored three-speed equalisation!

You're right about their earlier products, Nick, but I am casting a wary eye on the Dynatron TV in the corner - lovely cabinet, bog-standard Pye 697 chassis in there - 'nuff said....

[Paul_RK]

Originally Posted by Welsh Anorak

You're right about their earlier products, Nick, but I am casting a wary eye on the Dynatron TV in the corner - lovely cabinet, bog-standard Pye 697 chassis in there - 'nuff said....

Well, yes. The Hacker brothers owned the firm until '55, I think Ekco may already have begun making their TV chassis but nothing else: Ekco takeover in '55 with the Hackers staying on as managers; they left in '59 for the next phase of their story. I suspect the TRP-1's construction would have earned the approval of Ron and Arthur Hacker whether or not they were still at the helm when the machine was commissioned. Surprising really that Dynatron's non-TV products with few exceptions never did become Ekco/Pye/Philips clones after the fashion of what happened in short order when Regentone took over RGD.

Paul

[DMcMahon]

Refitted the removed capstan motor with the donated resilient mounting bush from the Challenge 44G2 Studio deck. The donated bush although the same profile is not identical size wise to the original bush's, it is wider and the central hole slightly larger.

The central hole being larger means that it does not grip onto the tapered mounting post but operationally should be OK.

The securing of the motor mounting lugs is different between the Challenge and the Cordova decks, on the Challenge the securing/fixing is done by hex headed machine screws, while on the Cordova the fixing is done by circlips into grooves on the tapered mounting posts.

David

[Christoffrad]

When I was a kid my father bought one of these Dynatron Cordova tape recorders. It worked very well except for one recurring problem.... The heat from the take up motor would cause the grub screw on the shaft to unscrew and then the shaft would slip. He must have spent a furtune having it fixed by Binns service workshop(unless under guarantee) and I was too young to tackle such a problem. In all other respects it worked perfectly. I eventually fitted a 4 track head and that worked too although I was too inexperienced to understand that the bias should probably have been adjusted for best results.

Chris

[DMcMahon]

That is interesting Chris, sounds unusual for the motor to get that hot.

When I get it powered up and running I will watch out for that.

David

[Edward Huggins]

I have one of these on the to-do list.
I'm a bit daunted by what I may need to have to do to it!
The circuit shows EQ for all 3 speeds, so will be interested to learn how this performs in due course....

[Christoffrad]

I have the original Blue Print and User Instruction card for this Dynadron version of this tape recorder. See thumnails.
I hope this is helpful. Please PM me if you need a Scanned copy.

Chris

[DMcMahon]

Very helpful thankyou, PM sent requesting original scan copy of the Operating Instructions.

David

[DMcMahon]

Received good quality scans of the Operating instructions and the schematic, thank you very much.

David