Tag: vetch

What the listing stated:

Can’t get to turn on unfortunately. No battery cover. Any questions please ask

EBay

I know, there is no battery cover, however I have already sourced a seller of one if needed. This item looks quite dirty so a good soak might be the order of the day to get started. I’ll wait for its arrival before I jump to order any other bits for it.

Now as I’ve said in the past these units fall into that crazy price category on the selling platforms as the “New Antiques” of today. For an item that was low cost, somewhere between £25-40GBP when it came on the market, they can certainly command a wide range of crazy prices, here is an example of price ranges from today:

This one I purchased today only came up for sale about 3 hrs ago and I thought it would have been snapped up by now, it hadn’t so I didn’t hang around any longer and purchased it for a total of £16:38GBP including its delivery. I’m not going to get too smug yet, as for all I know I may have just purchased an empty shell. Let’s wait until it arrives.

Here’s a little history of this unit:

Grandstand “Invader from Space” is a tabletop LED game dating back 45 years to 1980. Four ‘AA’ batteries power the unit or, alternatively, the Grandstand 5.5V@300mA power adapter (or an equivalent power pack) sold separately. The game, licensed to Grandstand, is a copy of Epoch’s “Invader from Space”

The company initially behind the “Grandstand” label was Adam Imports Ltd., (from 1980 Adam Leisure Group Ltd. and by 1983 Adam Leisure Group PLC) founded in 1973 by Chris Rycroft and Les Kenyon of Harrogate, UK. The company initially started as a mail order company and was the single largest supplier of calculators in the UK by 1974. By August 1978, George Bassett had acquired a 75% holding in the capital of Adam Imports for £750,000 cash, plus 60p in the pound of profits before tax in excess of £500,000 for year to December 31, 1978. Adam Imports was re-acquired from George Bassett by Chris Rycroft in 1980. It chiefly imported electronic products from other manufacturers such as VTech, Epoch, Tomy & Entex, selling them in the UK re-branded under the Grandstand name.

Wikipedia and others

So that’s the history

There is a good link to a similar repair on YouTube from a guy I follow named Stez Stix Fix, it’s very much worth a look and he has a great if not sometimes crazy way of diagnosing and repairing items. A cool guy though.

Anyway back to my own purchase.

Assessment:

I must admit the unit doesn’t look as dirty as in the original pictures. The battery cover is missing and there is a crack in the side and a deep scar at the bottom, this won’t be too much of an issue if I can weld it all back together. I will still give it a good soak to clean it all up though. I’ve put four batteries in place, and the unit is definitely dead. There are no loose wires, voltages are getting around the board according to the multimeter and nothing is getting hot. There appears to be no short circuits, and then I notice this, capacitor CO7, slight bulge on top and what looks like leakage from the bottom. We have a candidate as to why this unit is not working.

I’ll whip this out and see what we have but I suspect this old capacitor has failed and is causing an issue, heres hoping I have a suitable replacement.

Repair:

This little beast is a 330uf 10v electrolytic capacitor. I have none available so have had to purchase a pack of ten. These should be here in the next few days. There are three other old electrolytic capacitors that I will also change whilst I’m in there, as these are all likely to fail at some point soon. These components are now all around 45 years old, it’s a wise move to change them out.

I’ve ordered a 3D printed battery cover to replace the one that is missing. This should be here in a couple of weeks.

Whilst waiting I have cleaned the inside and outside of the casing as best I can. I still have a piece of broken surround to repair, however this is just a simple glue and a little bit of support job.

The surround that was broken has been repaired and secured with some nylon soaked in a superglue compound inside the casing. It’s rock solid. Outside the break is hardly noticeable. The break is secure and much stronger now.

I’ve replaced all the offending capacitors and the unit remains dead. I’ve reflowed most of the board as there were some dry solder joints. I’ve also rewired the bridge from the control panel to the main board as one of the wires here had broken.

After using the multimeter to check some traces and components it’s now pointing to this component (a power transistor D882) being the cause of this catastrophic breakdown as its readings are all over the place. I suspect this item has overheated, the capacitor has blown and then it’s just died itself. I’m probably wrong, but I know what I mean. Probably just a catastrophic chain of events that all contributed to the units demise.

And as usual I have none available so will have to send for some new ones. The new components have arrived and the new power transistor has taken its place on the board. Now reassembled I place some new batteries in and the unit comes to life. It was the power transistor at fault, I should have really checked here first after seeing that damaged capacitor at the beginning.

Not to worry though as it’s had a good overhaul and has been totally recapped as a precaution. I’ve used some conformal coating on a few tracks that had some copper exposed after a good clean, to ensure they don’t deteriorate any further.

The unit is looking really good and these items were traditionally very loud and this certainly is. It’s working well just as it should do and I’m exceptionally happy with this repair. I’m still awaiting the battery cover that I have had 3D printed and this should be here in the next week to complete the fix.

So with that I will bring this build to a conclusion. It has been a fun project, I’ve learned a number of things about this circuit board and gained valuable knowledge.

But best of all we have rescued another item and saved it from landfill.

Winner 🥇 👍

Thanks for passing by