11 Apr
2012
11 Apr
'12
3:47 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 09 April 2012 18:53
To: cctalk at classiccmp.org
Subject: Re: RD53 Disk Not Rotating
line
I hope I haven't made a mistake here. Rather
than go to Farnell where
I need a minimum order amount, I looked on Ebay and found someone
with
some TIP125s there.
I had assumed they were all the same and just chose this one:
http://www.ebay.co.uk/itm/TIP125-Transistor-
/290672643190?pt=LH_Defaul
tDomai
n_3&hash=item43ad708c76.
From what I can see, those are the right parts.
In gneral, if diffenrent manufacturers use the same part numberm the
devices meet the same publsihed specs. A TIP125 from TI is the same as oen
from SGS-Thomson. In a few cases, if you go outside the pnblished specs,
the devices will behave differently, this can be a problem in things like output stages (CRT horizotnal output stages), but I
don;t think this will
be a
problem with a motor driver
The '8702' number is almost certainly a date code. It doesn't matter.
Sometimes you'll find suffix letters on transistor numbers. These either
indicate the approximate current gain (for example the BC109C). or the
maximum voltage it'll withstate (TIP41C) or perhaps soemthing else.
That's when you need to look up the whole number in a databook to find out
just what the versions are. But I don;t think that's a problem here
either.
-tony
Just in case anyone is interested, replacing the failed Darlington
transistor fixed the problem. The RD53 now spins the disk again. Thanks to
everyone who helped.
Regards
Rob