Decca TPW70 Kitchen Radio

[Vintage_RC]

I have recently purchase a Decca TPW70. It is in generally good mechanical order, there are a couple of obvious faults which are visible in the picture ie broken resistor and capacitor with cracked case. The set is non functional at the moment but before I start the repairs there are a few problems which I could do with some suggestions:-

1) The PP1 battery has swollen and is jammed very tightly in the PCB, it is so tight I am surprised it hasn't cracked the PCB. Any suggestions about how to remove it without causing damage to the PCB would be welcomed.

2) The PCB is held on with two spring fasteners, the one on the left is clearly visible in the photo. These push over a plastic rod which is part of the case molding. They are essentially one way devices and I'm looking for advice on how to release them without harming the plastic rod.

3) Once one and two are resolved, are there any components which are likely to be in need of replacing. I'm thinking of the blue electrolytics and the black Hunts caps.

Thanks in advance, Alan

[Wellington]

Regarding question 2, the spring fasteners are called spire clips/nuts/fasteners, and are notorious on this forum. You can use the forum search function to search for "spire", and there is some useful info in this thread.

[G6Tanuki]

To preserve the PCB, I'd look to cut the battery up in-situ using a Stanley-knife or similar.

Your radio looks to be one of the early ones with the metal-cased STC/Brimar TK100x-numbered equivalents rather than the more-usual Mullard OC-series.

Intriguing to see that it uses a single driver-transformer output-stage (hence the two batteries in series to provide the centre-tap voltage) - that was rather adventurous in 1961!

[Vintage_RC]

Originally Posted by Wellington

Regarding question 2, the spring fasteners are called spire clips/nuts/fasteners, and are notorious on this forum. You can use the forum search function to search for "spire", and there is some useful info in this thread.

The clips are similar to the spire type but as you can see in the close up pictures they are different in detail and I think will need a different technique to remove them without damage to the posts.

[TonyDuell]

My TPW70 has the same type of clips and if you squeeze the tabs together (just finger pressure from the left and right sides in your first photo) they come off without any problems.

[Vintage_RC]

My clips were very tight but by gripping the tabs together with a pair of pliers I was able to remove them without causing any damage. Problem number 2) in my list now solved.

Regarding problem number 1) I have tried using a scalpel to separate the battery but it is so tightly jammed that reasonable force won't move the blade between the battery and the PCB.

[Nuvistor]

It will be messy but drill a line of holes along the centre of battery, squeeze the sides together may give enough to remove.

[Paul_RK]

The blue electrolytics are Daly, so among the worst of their vintage and best eradicated for reliable performance.

[Vintage_RC]

Nuvistor, drilling a series of holes sounds like a workable solution although as you say, it will be (very) messy.

Paul_RK, yes I thought those blue electrolytics might be cause for concern

[Vintage_RC]

I've made some progress. The PCB obviously had to be removed and this required the removal of the tuning knob. It proved to be quite tricky to get it off without damaging the irreplaceable knob or the PCB. In the end I succeeded, the spring clips did not prove to be a problem and with the PCB removed I got a much better view of the jammed in battery. I have attached a photo and will have a think about the options, any thoughts are welcome.

[poppydog]

I'd be tempted to keep running some freezer spray in the joint where battery meets board and try to get that board to shrink a little whilst wriggling that battery out.

poppydog

[Wellington]

The cardboard case of the PP1 looks a goner and I presume it will be sacrificed. Two ideas come to mind:

1. Lubrication/disintegration. Scratch the cardboard case of the battery where it meets the PCB (I see from the photo that this has already happened, partly) and allow some oil (or other liquid) to penetrate the cardboard. This may cause the cardboard to disintegrate giving you a bit more room to wiggle the battery out (and some lubrication, if you use oil).
   
2. Rather than scratching the cardboard where it meets the PCB, maybe it could cut with a sharp knife. Once it was cut all the way around, you could lift one cardboard 'hemicube' off and try and push the battery through the aperture.

(I don't know how resistant PCBs are to penetration by liquids)

[Refugee]

Surely on the track side of the board just crush the battery in a vice.
It should then drop out from the component side.

[Vintage_RC]

I'm not sure whether the vice approach would work because you would not be able to get the jaws right up to the PCB. I might try it however it is probably worth a try as there's nothing to lose.

[Refugee]

That is why I said di it on the track side.
Possible make a cut near the snap plate so that it can be pulled out first.
That will make more space for it to expand lengthwise.

[Vintage_RC]

I'll give it a try tomorrow.

[PJL]

You might be able to save the battery box by carefully opening the top of the box and pulling out the individual cells of the battery.

[Techman]

That's a classic vintage battery.

I would certainly be very careful to remove it in one piece so that it could be re-stuffed with modern AA cells. Hopefully you've got the one from the other side.

Sometimes the old batteries are worth more than the radio if their cases are still good and free from leakage damage.

[Vintage_RC]

Many thanks to Refugee for his idea of using a vice, the battery came out easily after squeezing it a bit as he suggested. The battery is still in reasonable visual shape so I will keep it. The other battery was not present when I purchased the set. I can now start some fault finding.

[Refugee]

Well done.