Author Topic: Resistor values  (Read 226 times)

0 Members and 1 Guest are viewing this topic.

Offline pledg

  • CPC664
  • ***
  • Posts: 54
  • Country: gb
  • Liked: 10
  • Likes Given: 1
Resistor values
« on: 14:19, 13 January 20 »

Hi,


Can anyone please confirm some resistor values for me on the CPC464.


Seems to conflict between the parts list/schematic and what is actually on my board reading the band colours!


R144 my board has 4.7k this is as the manual and schematic

R145 my board has 10ohms but the manual states 1k

R155 my board has 56ohms but the manual states 120ohms

R111 my board has 1m but the manual states 2.2k

R101 my board has 3.3ohms manual states 22k



Cheers


Paul.

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.183
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3904
  • Likes Given: 415
Re: Resistor values
« Reply #1 on: 14:31, 13 January 20 »
I can only assume you are reading the colour code wrong or looking at the wrong resistors. If R145 was 10R, then the CPC wouldn't start at all and you would have a completely black screen. What does R145 actually measure? Can you post a photo of the resistors?

And where is R155? As far as I am aware, they only go up to R154.

Bryce.

Offline pledg

  • CPC664
  • ***
  • Posts: 54
  • Country: gb
  • Liked: 10
  • Likes Given: 1
Re: Resistor values
« Reply #2 on: 15:38, 13 January 20 »
Thanks for your time, see attached resistor pic:

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.183
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3904
  • Likes Given: 415
Re: Resistor values
« Reply #3 on: 15:54, 13 January 20 »
From the picture:
R145 = 10M
R155 = 56R
R111 = 1M
R101 = 3.3M

Your PCB is according to the amended schematic, not the old schematic. All values are correct. Have a look here: http://www.cpcwiki.eu/manuals/Amendment%20Service%20Manual.zip

Also, I notice it doesn't have the original oscillator installed. Did you swap this?

Bryce.

Offline pledg

  • CPC664
  • ***
  • Posts: 54
  • Country: gb
  • Liked: 10
  • Likes Given: 1
Re: Resistor values
« Reply #4 on: 16:43, 13 January 20 »

Okay so it's a MC0002D PCB board and I should be looking at the updated schematics.


Thanks for the file.


Wasn't sure about the clock so I ordered another it came as low profile which I wasn't expecting. Should that be okay apart from questionable soldering???


Paul.

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.183
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3904
  • Likes Given: 415
Re: Resistor values
« Reply #5 on: 10:36, 14 January 20 »
Should be fine as long as it's 16MHz.

Bryce.

Offline pledg

  • CPC664
  • ***
  • Posts: 54
  • Country: gb
  • Liked: 10
  • Likes Given: 1
Re: Resistor values
« Reply #6 on: 10:28, 15 January 20 »

Yep, the CPC464 has now booted! See my other post!


Thanks for your help.