Decca Debutante TP75

[ted_ntsx]

Decca Debutante success story.

I just acquired (from a local modern junk/collectibles shop) a Decca Debutante TP75 transistor radio. I don’t normally collect transistor radios, but this one looked quite old and interesting. Its date appears to be 1962.

It was filthy, completely covered in brown nicotine. The “white” parts were actually dark brown. The woman in the shop told me it was in working order, and the reason it did not appear to work was that it needed an aerial connecting to it (yeah, right. It has an internal ferrite rod!). She buys stuff at auctions, so I suspect she was just repeating what she had been told. Regardless, I bought it anyway.

The original PP6 (?) batteries had been replaced by PP3’s crudely wedged in with bits of foam. On switching on it just crackled when the volume control was moved, but was otherwise dead. Injecting audio produced a loud noise, so the audio amp part was working ok. Injecting an IF signal produced nothing, so I decided to remove the PCB to check a few voltages around the OC44/45s.

Removing the PCB meant removing the tuning knob first.
Now, how to remove the tuning knob? Was it just a push-on, or was there a screw hiding somewhere. Looking at it with a magnifying glass (the old eyes are not what they were) it appeared that someone else had also attempted to prise off the tuning knob and, or course, had just broken the plastic shaft and then just jammed it back on somehow. A bit of pressure and it all just fell apart! Oh well, at least it’s off now.

The PCB was just held by 2 4BA bolts. An easy job to remove the board after unsoldering the external aerial wires.

Voltage checks ensured. Ah! The first IF amp has no collector voltage, and a quick resistance check revealed the first IF TX was completely O/C. Both windings! The TX was slightly “bent looking” and on removing it, it was quickly apparent that a twiddler had screwed the slug right down the former and sheared off all the wires.

Ho-hum…. Just needs an aerial eh?

I found a smaller type TOKO IF can in my junk box that looked like it could be made to physically fit the board. This radio has an IF of 472, but I had no idea what frequency this TX I found was. I didn’t even know if it was an IF coil or an OSC coil! I bent the pins out a little and soldered it in, and was quite surprised when the radio burst into life, loud and clear.
Wow… lucky or what?

As the only real fault was the O/C TX, it made me wonder why someone messed about with it in the first place?

After cleaning the crackling volume control and wave-change switch contacts it worked beautifully. I put the PCB back in the case and then used a strip of wood to hold the PP3’s in place firmly, rather than the bits of foam, and that seemed fine.

The last problem was to glue the bits of the tuning knob back together. Not a great repair, but should be ok if treated with a light touch. A bit of ‘slack’ on the tuning knob makes it a bit fiddly to tune in though. (What’s the chance of finding a replacement knob? Zero probably.)

After cleaning the brown nicotine off the white plastic bits, and lightly cleaning the cabinet it now looks somewhat better. I don’t want to make it look too good as I prefer the used look (The patina of the ages? After all, it is 50 years old!).

Ted.

[SeanStevens]

A very pleasant looking radio - look after it

SEAN

[bobbyball]

That's a nice looking little radio, no wonder you went for it!

You were very lucky with the coil, well done there!

Robert

[Hybrid tellies]

A nice and a bit rare model. Well worth saving.

[Racalfanatic]

Very nice indeed. Could you please post a photograph of the circuit board?

[AC/HL]

There is a complete restoration article in the current BVWS Bulletin.

[ted_ntsx]

Originally Posted by Racalfanatic

Very nice indeed. Could you please post a photograph of the circuit board?

Sorry, I can't.

Unfortunately, removing the rear cover only shows the print side of the PCB.
To see the component side I would have to remove the PCB, which would mean removing the tuning knob first, and that is in a very precarious glued-together condition and would almost certainly break if stressed again.

Ted.

[Paul Adams]

Originally Posted by Racalfanatic

Very nice indeed. Could you please post a photograph of the circuit board?

I have one of these, found in a bin of all places I don’t normally collect radio’s but I just couldn’t forgive myself, if I left it there.

There seems to be a problem with the tuning capacitor, as when you apply pressure by pressing on it, it works.

I have checked for bad joints, but I fear someone in the past has put undue force on the tuning cap and bent the vanes.

Anyway I had it apart so here’s the photo’s that ‘Racalfanatic’ wanted.

Paul.

[ted_ntsx]

I did read somewhere that the Plessey(?) tuning capacitor is known to be a "cheap & nasty" component, prone to mechanical failure. Fortunately, mine seems to be fine

Thanks for providing the photos.

Now, if anyone happens to have a spare tuning control knob for one of these sets...

Ted.

[Phil G4SPZ]

I was also given one of these recently, in a cream colour. Your posting, plus the Bulletin article, have caused me to bring this set to the top of my own 'to-do' pile!

If it turns out to be irreparable, I'll offer it on the Forum for spares.

[ted_ntsx]

Originally Posted by Phil G4SPZ

I was also given one of these recently, in a cream colour. Your posting, plus the Bulletin article, have caused me to bring this set to the top of my own 'to-do' pile!

If it turns out to be irreparable, I'll offer it on the Forum for spares.

Hi Phil,
Whilst I would not wish to encourage someone to scrap anything repairable, if it does turn out to be past repair I would certainly be very interested in acquiring the Tuning knob and Pointer!

Ted.