I have a Pulsar watch, haven't used it for at least 10 years & can't find the manual. The model no. on the back seems to be W850-4030. Can you help?

that looks like a serial number. The 266th watch made in 1978.

Pulsar seem to use a few different batteries.

https://www.google.com/search?q=Battery+for+Pulsar+men%27s+watch+780266

This is the best advice

https://www.fixya.com/support/r27181038-changing_watch_batteries

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Clearly, it is faulty and has some type of parasitic drain. All watch batteries should last a couple of years. My Seiko last for about 3 to 4 years. Return it to Pulsar or a repair agent for repair.

Pulsar Watches - Tell it your way

https://www.pulsarwatches.com.au
Service & Repairs Service Agents Watch Care FAQs Instruction Manuals · Contact. PULSAR. Pulsar. ©2021 Seiko Australia. All Rights Reserved.
‎Watch Care · ‎Customer Service · ‎Abbreviations · ‎Glossary

Pulsar Watches - Contact

https://www.pulsarwatches-europe.com Pulsar burst onto the world watch scene with the first ever LED watch. Ever since, the name has been synonymous with adventurous and leading edge design.

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Best advice.

Tip & How-To about Watches

Changing Watch Batteries
Lots of posters ask "what is the battery in my (name of watch)" with a view to changing it yourself. This is a bad idea for many reasons. You don't have the tools or knowledge to remove a rotary screw on back, or the gasket sealant for a waterproof watch. Some fashion watches have 4 traditional screw and need professional grade jeweler screwdrivers. Also, there are about 20 batteries commonly used in watches, in various sizes and internal technology, Lithium Ion, Silver Oxide and Manganese Alkaline. If you buy them, you generally have to buy 10!

Don't sweat the details. Just take the watch to your local jeweler. They have all the batteries at hand and the tools to remove the back. It is done whilst you wait for $8 to $15!
Posted by ADMIN... on Dec 31, 2018

Or risk it

pulsar watch batteries - Amazon.com

https://www.amazon.com > pulsar-watch-batteries > k=p...
Duracell 370/371 Silver Oxide Button Battery, 1 Count Pack, 370/371 1.5 Volt Battery, Long-Lasting for Watches, Medical Devices, Calculators, and More.

Spotting Fakes

https://www.google.com/search?q=Pulsar+Y513-8159+spotting+fakes

Value $75 new, $25 used

https://www.google.com/search?q=Pulsar+Y513-8159+value

Pulsar Watches & 1980-1989 Year Manufactured
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Tip & How-To about Watches

Changing Watch Batteries
Lots of posters ask "what is the battery in my (name of watch)" with a view to changing it yourself. This is a bad idea for many reasons. You don't have the tools or knowledge to remove a rotary screw on back, or the gasket sealant for a waterproof watch. Some fashion watches have 4 traditional screw and need professional grade jeweler screwdrivers. Also, there are about 20 batteries commonly used in watches, in various sizes and internal technology, Lithium Ion, Silver Oxide and Manganese Alkaline. If you buy them, you generally have to buy 10!

Don't sweat the details. Just take the watch to your local jeweler. They have all the batteries at hand and the tools to remove the back. It is done whilst you wait for $8 to $15!

Posted by Andrew... on Dec 31, 2018

https://www.fixya.com/support/r27181038-changing_watch_batteries

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Pulsar are made by Seiko and support can be obtained from their web site. (The number your quoted is a Seiko number- all Pulsar models seem to start with two or three letters).

Put "www.seiko.co.uk/support/instructionbooklets" into you search engine and you should come to the Seiko instructions list. Scroll down to find your watch and download the instructions.

http://www.seikowatches.com/support/ib/index.html
　


Use the numbers on the back of your watch and you will have a PDF version of your instruction manual.

Hope this tip helps
R/
David

To set the timer hand on these models of Pulsar watches, do the following: 
Looking at the face of the watch, there are two buttons and a crown on the right side. The TOP button is Button "A". - The BOTTOM button is Button "B".
There are 3 positions on the crown: IN (#1), FIRST CLICK (#2) & SECOND CLICK (#3).
First, pull the crown out to the second 'click' position (#3) ... This is all the way out. (STOP THERE! Pulling harder will harm your watch! Don't try to pull past position #3!)
Push and hold Button "A" for two (2) seconds. The dial will sweep around to the 12 O'clock position. You can advance the timer while the crown is in position #3 (second click out) to reset it back to the default position. 
The manual says that if you pull the crown out to position #3 while the timer is measuring, the hand will reset back to the 12 o'clock position... I haven't tried that, so I can't confirm.

Operating manual for Pulsar, YM62. ALARM & CHRONOGRAPH.
http://www.pulsarwatches.com.au/files/instructions/137_1.pdf

This is an exact copy of my user's manual (instructions) that came with the mod. YM62.

I have a Pulsar watch and on the expandable band, the casing fell off and can't get it replaced unless we take off a link...To me this was too much trouble, time and expense...I won't buy another Pulsar! Too bad cause I thought it was a beautiful watch.