1961 Decca TP50 Debonette 6 transistor MW/LW portable

[howard]

Hello again,

I've been after one of these little Decca Debonette sets for some time and I managed to win a reasonable looking red one off ebay recently for not a lot, plus I had a scrap TP50A set for spares. The early Decca transistor models in my collection with their simple styling are rather cute looking sets, but under the skin they're nothing special. The TP50 model was originally powered by two PP4 9 volt batteries which are long obsolete but it's straightforward enough to adapt the set to accomodate two PP3s. The slightly larger and later 1962 TP50A was powered by PP6 batteries and rather than a 3.5 inch diameter Japanese 80 ohm speaker has a 125 ohm Rola loudspeaker. Both sets have a complement of the same early OC series germanium transistors although the two OC81 output transistors in my set had been replaced with 2GT182s. This example arrived grubby, had one damaged knob and one brass knob bright missing and a couple of tiny bits of rexine had worn through on the top edge of the case.

Four individual PP3 wired connectors were fitted to the PP4 battery contacts and two PP3 batteries connected up but the set was completely dead. The volume potentiometer and waveband/on off switch were cleaned with DeoxiT but that made no difference. The set was taking only 2mA current so not much was going on in there. Several blue Daly electrolytic capacitors were evident on the PCB so four of those (those which were easily accessible) were tested with my ESR meter and surprisingly they were OK. Ron Bryan offered to take a look at this set.

One of the output transistors was found to be duff, once replaced with an AC128 the set started to work with LW working rather better than MW. Three 0.01uf torpedo shaped caps and a 0.05uf paper wax cap on the PCB were checked and all were found to be very leaky so they were replaced with Vishay polyesters and the set perked up a bit but still worked better on LW than MW. Both IF and RF alignment were performed and performance improved but still it was working better on LW. So next the MW aerial coil was removed from the ferrite rod and checked with a Q meter, and compared with the one similarly removed from the scrap TP50A and the results were all but identical, so that was put back. Capacitors in the aerial circuit were all tested and all were OK.

It was noticed that the strong local radio station Eagle Extra on 1566kHz MW sounded distorted and quieter than the weaker Absolute Sounds station so the AGC capacitor was suspect. This is another Daly 10uf electrolytic well hidden under the tuning capacitor, and when tested after removal was found to be open circuit. That was duly replaced and at last MW perked up considerably, as did LW which is still a touch better than MW, even after repeat RF realignment. Still, the set performs well enough now on both wavebands so finally the remaining 2GT182 output transistor was replaced with a new AC128. The quiescent current tested OK.

The cabinet was cleaned with Sainsburys carpet and upholstery cleaner and once dry the loose threads of rexine along the top were glued down with just a smidgeon of superglue and carefully touched in with matching red acrylic paint. Two decent knobs were made up from the four from the TP50 and TP50A. The head of one of the bolts which secures the PCB to the case had sheared off. It was impossible to release what was left of the bolt so the small square wooden packing piece glued and stapled to the case which houses a nut underneath was removed and replaced with an identical one removed from the TP50A, and glued in place with wood glue. The set was then reassembled and given a polish with Mr Sheen.

This is a lovely looking little transistor radio and it works well now. My thanks to Ron for sorting out the PCB.

Howard

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[Paul_RK]

Hello Howard,

Very nice job as ever, and I like the way Decca's "house style" of the period was maintained from the Debonaire through these models to the still smaller Debutante. I think the Japanese 'speaker here as well as the output transistors must be a replacement, as the model dates from a few years before Japanese units started turning up at all commonly in UK-built sets. My TP50 has a round Elac, Decca fitted Elac 'speakers in most of their early transistor sets as far as I can recall.

Paul

[howard]

Hello Paul,

You may well be right about the loudspeaker, but this one does seem to have been fitted rather well ! On RMOrg there are two of these with their back covers off, one has a Celestion, the other is unbranded but different. I have a spare British loudspeaker in the scrap TP50A, I may well now fit it to this one.

Regards ..... Howard

[howard]

The plot thickens, here's another TP50/TP50A with a Jap loudspeaker ....

http://golbornevintageradio.org/gall.../60/categories

I think maybe the original loudspeakers do tend to fail in these models.

Howard

[Pamphonica]

Nice job Howard - a very stylish little set brought back to full working order.
Well done!
regards
Jeremy

[howard]

Thanks Jeremy,

They are very nice little sets.

I've now fitted an original 3.5 inch Celestion 125 ohm loudspeaker taken from the scrap TP50A complete with original wires and clips. It sounds better with this loudspeaker

Howard

[Hybrid tellies]

Another nice job Howard. A lovely looking set and probably sounds good to.

[nigelr2000]

Hi Howard I know this threads old but I have just done one of these for a customer. It has an Elac loudspeaker fitted and it looks original. Also LW is better than MW on this one as well.