Hi All,

I'm repairing a couple of old Grandstand Astro Wars games. I'm following the diagnosis approach from a couple of places (this Youtube video and some of threads on this forum, e.g. here and here). The first unit was a faulty D882 transistor and that fires up fine now after replacement.

The second unit (my actual original from when I was a kid) appears to have the faulty zener diode issue mentioned in those forum threads with a good replacement apparently being a 1N5275B zener diode. Unfortunately, they don't seem to be easily available anymore so I'm looking for an alternative.

The specs for the 1N5275B are here (on Mouser) and the nearest thing I can find is here (on RS) but there are differences, and I don't know how significant they are.

Any help would be appreciated.

Thanks in advance,

Dave.

 

Welcome to AAC!

1N5275B is 140V ½W zener diode. This seems a bit high voltage for an electronic game.
Can you provide circumstantial evidence why you think this is the correct part number?

 

Welcome to AAC!

The Mouser page had a broken link to the datasheet.

 

Welcome to AAC!

1N5275B is 140V ½W zener diode. This seems a bit high voltage for an electronic game.
Can you provide circumstantial evidence why you think this is the correct part number?

It does, but this is the quote from the thread mentioned above:
" For what it's worth, I fixed one of these with the exact same issue by replacing S06. I used a 1N5275B though. "
When you read earlier in that thread there is a mains driven, regulated, 140v feed to a vacuum fluorescent display (VFD) so it sort of makes sense.

 

If you cannot find 140V zener diode you can connect two zeners in series to make up 140V.

Two 1N4760 68V zeners give 136V.
Use 500mW or 1W zeners.

https://uk.farnell.com/vishay/1n4760a-tap/zener-diode-aec-q101-1-3w-do-204al/dp/2547242

 

Thanks for all your help @MrChips @Irving @dl324 , and for making me feel very welcome.

As Irving referenced, I was following the previous forum post as far as the spec of the part needed, and it was apparently successful.

@MrChips I was wondering about connecting in series but didn't know if it would work or what parts I'd need so that's perfect, thank you. I'll get some of the 1W ordered from Farnell. It's 30 odd years since this thing last ran so would be great to see it going again.

All the best.

 

FWIW Digikey has the NTE equivalent zener diode in stock. The 1N5275B crosses to an NTE5054A. Cost $1.54 each with a minimum order of 3.

Dan

 

Hey,

I just wanted to come back to say the help I got here got my old game fixed and working. I followed the advice on using two 1N4760 68V zener diodes in series and it worked perfectly. I showed it to my Mum (who plugged the wrong adapter in the first place) and she had another go

So thanks all, I appreciate your help!

All the best,

Dave.