IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
> 420 with bad note?
hodad
post Feb 16 2008, 11:06 PM
Post #1


Starting Member
*

Group: Members
Posts: 2
Joined: 16-February 08
Member No.: 3,626



I just picked up an old 420 that tunes my guitar fine except for the B, which seems to be off by maybe 12 cents. Is this a common problem, & is it reasonably easy to fix? I'm reasonably good with electronics repair but haven't opened the tuner up to take a peek yet.

Thanks
Tom
Go to the top of the page
 
+Quote Post
John Norris
post Feb 18 2008, 01:53 PM
Post #2


Strobe Tuning Guru
******

Group: Root Admin
Posts: 2,608
Joined: 12-June 02
From: USA
Member No.: 3



No, its very unusual, even for a 40-year-old tuner like the 420. The reason is that unlike the earlier 1960s Model 400, the individual notes are not trimmed, so its more likely for all notes to go out of whack on a 420.
Even then, for it to be a constant 12 cents is unusual, as a malfunctioning IC will be quite random and unlikely to produce the effect described.
A failed motor bearing would also not produce a constant flaw as you describe.
Hard to say without seeing it.

John N.
Go to the top of the page
 
+Quote Post
Sue
post Feb 18 2008, 02:02 PM
Post #3


Peterson Technician
***

Group: Root Admin
Posts: 168
Joined: 14-September 02
From: USA
Member No.: 63



Hi,
If you would like a schematic please email me directly and I'll mail one out.
~Sue
Go to the top of the page
 
+Quote Post
hodad
post Feb 19 2008, 06:52 PM
Post #4


Starting Member
*

Group: Members
Posts: 2
Joined: 16-February 08
Member No.: 3,626



I checked further, and found the following:
1. it's not a constant 12 cents. It was right there the first two times I checked, but not again.
2. The A# is also off.
3. The motor is louder in certain note positions than in others. It's definitely louder on the B than on most other notes.I don't know if this could be indicative of a bad motor bearing or not.

Thanks for your help so far!

Tom
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



Lo-Fi Version Time is now: 31st October 2014 - 03:45 AM