# Need help identifying old capacitors from the 70's.

#### Kream dream

Joined Aug 28, 2017
1
I'm working on a pong machine from the 70's and I want to replace the caps. I'm having a hard time finding information on certain caps as it seems they changed the way to identify them many times. I'm not sure if this is the right place to post this or if this is the kind of group I think it is but I'm working on fixing old gaming electronics all the time and would love s forum to ask questions and get good feedback ( if this is not the place please direct me if you know one).

Thanks.

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#### dl324

Joined Mar 30, 2015
8,760
Welcome to AAC!

The last three look like they conform to the practice of specifying capacitance in pF. First two digits are the value and the third is the multiplier. 102 would be 1000pF. Letter suffix probably accuracy.

First picture has glare and not clearly focused.

That type of cap rarely fails.

#### MrChips

Joined Oct 2, 2009
19,154
152 = 1500pF = 1.5nF
102 = 1000pF = 1nF
104 = 100000pF = 100nF = 0.1μF
473 = 47000pF = 47nF = 0.047μF

The last two appear to be mylar capacitors.

As dl324 suggests, I would not bother to replace any of those capacitors. They are not likely to fail.

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,562
473 = 47000pF = 47nF = 0.047μF
OR 47+ three zeros's pF = 47000 pF

#### GopherT

Joined Nov 23, 2012
7,983
I'm working on a pong machine from the 70's and I want to replace the caps. I'm having a hard time finding information on certain caps as it seems they changed the way to identify them many times. I'm not sure if this is the right place to post this or if this is the kind of group I think it is but I'm working on fixing old gaming electronics all the time and would love s forum to ask questions and get good feedback ( if this is not the place please direct me if you know one).

Thanks.

http://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors.html

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,562
Those types of capacitors (metal film Poyester) don't usually go bad.
Electrolytic's typically go bad. They also are sometimes voltage rated too low.

#### Hypatia's Protege

Joined Mar 1, 2015
3,186
I'm working on a pong machine from the 70's and I want to replace the caps.
Re: the capacitors shown in the images - Unless you have reason to believe they've suffered electrical abuse (CIP 'over voltage') - no need to bother... Polymer film Caps appropriately applied to decoupling and small signal AF almost never degrade or fail with use/time...

That said, 'preemptive recapping' of all electrolytic Caps is a highly recommended initial step of any restoration project

Best regards and good luck!
HP

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,562

#### Hypatia's Protege

Joined Mar 1, 2015
3,186
Yebut they make lovely Independence Day 'fire crackers' under inverse polarity

TTFN
HP

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,562
Yebut they make lovely Independence Day 'fire crackers' under inverse polarity
Even better when you take those can electrolytic caps and hook them up to the mains. (Don;t try this at home).

Take a 12 V device (CB Radio) and hook it up backwards to a train transformer. Popcorn. Yum!

#### recklessrog

Joined May 23, 2013
988
When we were children, we had trouble with rats. A neighbour modified a mouse trap to not only try and catch the little blighters, but wired a pair of contacts to the trap that would complete a circuit from the live mains to a an old metal cased sealed electrolytic capacitor. In those days, the 240 Volt 15 Amp plugs and sockets were not individually fused, only at the fuse box which he had wired up with thick garden wire.
We were all awakened a few nights later by the arrival of the fire brigade who after dowsing the fire that had been started in his shed, retrieved a decapitated large rat covered in what looked like a severe case of dandruff, being the innards of the capacitor which had exploded with considerable force!!!
The neighbour was suitably reprimanded by the fire chief, and a few days later our local exterminator came round and put highly toxic poison (Arsenic?) down. This resulted in the death of at least two cats and a dog and the hospitalisation of one small child.
I don't think the rat problem was cured until the area was bulldozed and a new housing estate was built there!!

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#### recklessrog

Joined May 23, 2013
988
I think the 1H is the voltage rating if my memory is correct, 1H being 100 volts

#### PhilTilson

Joined Nov 29, 2009
75
When we were children, we had trouble with rats. A neighbour modified a mouse trap to not only try and catch the little blighters, but wired a pair of contacts to the trap that would complete a circuit from the live mains to a an old metal cased sealed electrolytic capacitor. In those days, the 240 Volt 15 Amp plugs and sockets were not individually fused, only at the fuse box which he had wired up with thick garden wire.
We were all awakened a few nights later by the arrival of the fire brigade who after dowsing the fire that had been started in his shed, retrieved a decapitated large rat covered in what looked like a severe case of dandruff, being the innards of the capacitor which had exploded with considerable force!!!
The neighbour was suitably reprimanded by the fire chief, and a few days later our local exterminator came round and put highly toxic poison (Arsenic?) down. This resulted in the death of at least two cats and a dog and the hospitalisation of one small child.
I don't think the rat problem was cured until the area was bulldozed and a new housing estate was built there!!

#### PhilTilson

Joined Nov 29, 2009
75
That puts me in mind of an incident in the 1950s. I was about six years old and we had gone as a family to the cinema the night before to see Walt Disney's Snow White and the Seven Dwarves.

As one did in those days (and probably still do!) my sister and I were 'acting it out' the following morning; I was the wicked witch. For some obscure reason, it seemed a good idea to try to create a 'spell' by plugging my older brother's crystal set headphones into the 240V, 15 Amp, unshuttered power point. Well, it certainly created a flash and a bang! - but I seem to remember my brother being puzzled as to why he couldn't listen to The Goon Show that evening...

#### leeleduc

Joined Oct 9, 2008
1
I'm working on a pong machine from the 70's and I want to replace the caps. I'm having a hard time finding information on certain caps as it seems they changed the way to identify them many times. I'm not sure if this is the right place to post this or if this is the kind of group I think it is but I'm working on fixing old gaming electronics all the time and would love s forum to ask questions and get good feedback ( if this is not the place please direct me if you know one).