Audio & Hi-Fi Reditune TP48: Earlier Model, Non Automatic

They must be attracted to you, like moths to a bright light! Just when you thought you'd never see another one.

It's certainly in better condition than the previous one. The transistors in the 'new' (but older) one look as though they might be germanium types. It will be interesting to unclip them from the retainers, to try & see the type numbers.

I have a vast collection of transistors here if you get stuck.

David.

Hi David, they certainly do look like Germaniums, there were a few in Swampy below deck, it only had the lockfits on the little board up top, whereas the new(old) has germanium up top as well.

If you have any more belts in stock and were willing to sell one, I'd certainly like to purchase one for this unit. As I mentioned above, I'm using a cut and shut affair for now. I could steal swampy's, but I really don't want to upset him, nor give him the impression he's going to be abandoned. They will both time-share responsibility for providing museum entertainment.

What I also need to do now is find a mother load stash of tapes.

Update:

Perhaps readers of the previous TP48A thread may recall (swampy), the unit had been poorly stored, also apparent was the state of the small Philips blue electrolytics, they were pretty much all shot.

This new(old) TP48 has clearly been more looked after, and even though a few years earlier than swampy, it still has a number of these electrolytics. On an initial inspection, they all looked to be in reasonable condition, though that as we know cannot be relied upon.

Dismantling the lower deck to gain access to the various sections of the circuit, I did find a 20uF that had puked and another, a 64uF up top. Checking these two in-circuit, shows the 20uF reads as leaky and high ESR. The 64uF has risen to 261uF.

Without a circuit diagram, I'm hoping the 64uF that has leaked and gone high, is possibly the culprit for the extremely low audio output. The positive side of this cap is connected to the positive side of the audio head. The other cap, the 20uF, appear to be connected to one lead which goes off to a Varley relay.

Time to delve in, I think I'll try the one connected to the audio head first.

The small ceramic capacitor across the screened lead looks interesting, I wonder if it was to help stop radio breakthrough on the amplifier.

Well that was a simple fix, the extremely low audio was as suspected, a result of the 64uF 25V electro, in the feed from the audio head having risen to 289.2uF. 

Replaced with a new 68uF 25V, I now have bags of volume. I'll leave this one running for the rest of the afternoon and evening to see if anything else develops. The good thing on this one is the tone works, as you can probably hear from the demo, more bass.

The other cap, 20uF 25V that was connected to the relay was also replaced as when out of circuit it tested as 1uF. No idea of its function.

Sometimes it's nice to have a simple fault especially when you have limited information. I wonder how many carts a typical setup had and in the case of the manual track change who changed the track and made the choice of what carts to play? Today it's all managed remotely but you might have a chuckle at a service call I had the other day. Don't know who the contractor was in 2019 but media player simply had the wrong IP address.

Posted by: @jayceebee

I wonder how many carts a typical setup had and in the case of the manual track change who changed the track and made the choice of what carts to play?

I've wondered that too. From what I can gather, and there's very little info out there, it varied. Early machines had to be purchased, then they moved to a rental only business model, which is why so few machines survive. The tapes, as far as I can tell, went the same way, rental only. I think you paid rental for one tape, could send it back in their special boxes, and receive a different tape back.

I suspect Reditune had various rental plans, a business with a bit more cash flow might have rented a suite of tapes. I did read on another site a chap worked in a shop where they had the same tape for years, and it drove him nuts listening to it day in day out, and he looked forward to the Christmas tape just for the change.

As for track change, I guess that's why the TP48A came in with its auto track change. Then successor the TP80, which took track change from mechanical solenoid to shift the head up and down, to a fixed 4-track head with electronic track switching.

As rare as the carts for these machines appear to be nowadays, last week I managed to obtain a further 6 for the Museum's background music system. This now brings the collection to 14 carts.

Before attempting to play them, I shall, like the previous ones I acquired, dismantle and service the internals. One of the carts splice has failed and one has snapped, both are easy fixes.

I've had the Reditune system playing all day, also sharing the load my homebuilt Reditune for the past 5 months, and have become very accustomed to the delightful nostalgic tunes. Looking forward to hearing what's on these new ones.

First cart service; initially unknown content, as no descriptive label. The fault with this one was the tape had spooled off the guide path. A result found inside, I've been hoping to get hold of a Christmas cart, this cart has an Xmas 88 sticker. Quite surprised at the date, I thought these would have long been shelved by then in favour of more modern cassette systems.

Posted by: @crustytv

. I did read on another site a chap worked in a shop where they had the same tape for years, and it drove him nuts listening to it day in day out, and he looked forward to the Christmas tape just for the change.

Having worked in a couple of different factories that have had Metro Radio playing over the PA system, I know EXACTLY how that feels! 

If I hear Ed Sheeran one more time...

A little update to this thread

As can be seen from my YouTube demonstration above, I had purchased a Siemens Speaker cabinet to use with the Reditune system. Since then, I've been on the lookout for a Rediffusion speaker, low and behold one turned up last week and I managed to snaffle it.

This speaker is not the one that would have come with the TP48, but finding one of those is unlikely, so this is the closest I will get. It's more suitable and in keeping with the Reditune system than the large green speaker Box I currently use. The Siemens is an excellent speaker, and with its massive reel of speaker cable, well suited to providing music in the garden, which is how it will be used from now on, with the Rediffusion taking over internal duties. As ever, some pictures for your perusal.

A short 30-sec demo

My only concern is that the Rediffusion Police don't come round to arrest you as you may have removed that back panel without being authorised ?

I noticed the sound was a little distorted this morning, looking inside the .25mfd 350V paper in oil was leaking, the .01mfd 1000V Sprague looked ok.

Anyway, I changed them both and while I was at it replaced the short speaker cord with a long two spade cable. Luckily, a while back an ex trade gentleman sent me his ex stock of cables, so I'm spoilt for all the different period types.

Anyway, it sounds much better and now without any distortion.