• AVR Freaks

PIC18F2550 Timer1 External Clock Source Crystal not running

Page: < 12 Showing page 2 of 2
Author
Post
Essentials Only Full Version
coffee critic
Super Member
  • Total Posts : 394
  • Reward points : 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 10:38:33 (permalink)
+1 (1)
Are you sure these are ceramic caps?  Most leaded ceramic caps are marked with EIA standard 3 digit marking.  The only exception is with 1% parts that can have 4 digit marking. 
 
Can you take a picture? I should be able to tell by looking at the part. 

n_*$
#21
Joel QO
New Member
  • Total Posts : 27
  • Reward points : 0
  • Joined: 2014/09/28 11:52:38
  • Location: 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 12:12:09 (permalink)
0
This is the picture of one of the capacitors.
 
I've been reading about ceramic capacitors marking and it's usual to mark them with only the numbers representing their value in pF. 
 
In this case "22" pF.

Attached Image(s)

#22
coffee critic
Super Member
  • Total Posts : 394
  • Reward points : 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 13:37:18 (permalink)
0
What you have there is a single layer ceramic capacitor.  Most of those went out of favor back in the 1980s unless they were used for a high voltage socket.  They did not use the EIA markings, just the value and the rated voltage. Were these found at an electronics surplus place?    

n_*$
#23
Joel QO
New Member
  • Total Posts : 27
  • Reward points : 0
  • Joined: 2014/09/28 11:52:38
  • Location: 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 13:49:57 (permalink)
0
Hahaha 😂. Well, I'm from Colombia.
the electronics market is very old in here.
That's the reason why I'm working with PIC18F2550 and not with the PIC18F25K50.

It's really difficult to find updated electronics in here.

So while I'm doing the prototype I use what I can find in here, later for mass production I usually "update" the components.

Without mention, the importing costs for electronic components.

🤷🏻‍♂️
post edited by Joel QO - 2018/10/29 13:51:58
#24
coffee critic
Super Member
  • Total Posts : 394
  • Reward points : 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 14:02:47 (permalink)
0
Were these soldered or in a bread board?  These caps were prone to cracking if too much heat was applied during soldering. 

n_*$
#25
Joel QO
New Member
  • Total Posts : 27
  • Reward points : 0
  • Joined: 2014/09/28 11:52:38
  • Location: 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 14:08:25 (permalink)
0
I'm using an iron tip with a controlled temperature at 250°C
#26
coffee critic
Super Member
  • Total Posts : 394
  • Reward points : 0
  • Status: offline
Re: PIC18F2550 Timer1 External Clock Source Crystal not running 2018/10/29 17:04:10 (permalink)
0
I suspect these parts when assembled way back when might have used non RoHS Sn-Pb solder ~ 235C soldering point.  Newer multilayer caps use much Pb free solders that are much higher temp.    Back to your last comment, your 250C iron won't be a problem as long as you only touch for a second or so.  Any longer than that might cause the ceramic to lead wire connection under the epoxy to melt. 

n_*$
#27
Page: < 12 Showing page 2 of 2
Jump to:
© 2021 APG vNext Commercial Version 4.5