Jump to content
The Mr. Video

Laser 128 won't turn on

Recommended Posts

Posted (edited)

Hi, I tried to use my laser 128 today, but when I turned it on, I heard something pop inside and the computer smelled like something was burning inside. When I opened up the computer, I checked the power regulator section and noticed that the small chip there had a chunk blown off the top with its insides exposed. Does anybody know what chip it is so I can get a replacement?

 

20210503_210019.jpg

Edited by The Mr. Video
Scene of the crime

Share this post


Link to post
Share on other sites

That big cap in the foreground there looks swollen, as well.  Could be what caused the circuit to fail.

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, Baldrick said:

According to the schematic, that's U1, which is a 74HCT244

 

https://ia800709.us.archive.org/12/items/Laser_128_Technical_Reference_Manual_alt/Laser_128_Technical_Reference_Manual_alt.pdf

See page E-12 and F-1

 

And do replace that swollen capacitor.

Does the brand of the chip matter? Or is it just a generic ic?

Share this post


Link to post
Share on other sites
Posted (edited)

Generic.  And they cost a dollar new at Digikey.

You can order that replacement capacitor while you're there.  Mind the voltage and temperature rating of the capacitor.

(and the size).  If you can get a similarly sized cap with a slightly higher voltage and temperature rating it will guarantee longevity. Especially since it is sitting right next to a 5 watt resistor which can emit a LOT of heat.

Edited by Baldrick
  • Like 1

Share this post


Link to post
Share on other sites

I looked through Digikey's selection and they did not have any that would fit the laser. The current chip has 7 pins on each side and all the ones I saw on Digikey have 10 on each side. I can't even figure out how to get the power board out of its shielding so I can solder.

Edited by The Mr. Video

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...