On Wed, 01 Dec 2010 13:28:11 -0800, klem kedidelhopper wrote:

On Dec 1, 3:53Â*pm, Meat Plow wrote:
On Wed, 01 Dec 2010 12:35:56 -0800, klem kedidelhopper wrote:
On Dec 1, 3:11Â*pm, Meat Plow wrote:
On Wed, 01 Dec 2010 11:54:20 -0800, klem kedidelhopper wrote:
Someone gave me one of these that he says smoked. I found a small
burned diode, Â*(looks like a 1N4000 series size) on the regulator
board.This diode was soldered accross C1 with the cathode
connected to the positive terminal of C1.This part looks like it
must have been a production change as all other parts are labled
on the board but this one the board is not labled for it and so it
looks like it was a factory modification. Tripp Lite won't help me
at all with this problem. So I was hoping that someone might have
run into this before who might have any information on this and/or
perhaps a schematic that they could share. Thanks for any help.
Lenny

What happens when you replace the diode?

--
Live Fast, Die Young and Leave a Pretty Corpse

WelI I haven't replaced it as of yet because I don't know if it was
just a diode or a zener. And not knowing this and what else might be
wrong I wouldn't want to compound the problem. Lenny

If it's a zener it would be clamping voltage on a reg circuit. Not
knowing what C1 is or does it's hard to say what its function is but I
would take an educated guess and say it's not a zener. I suppose you'll
need to figure out how C1 plays into the circuit. Personally I would
ramp the source up using a variac and watch what kind of voltage
developed where the cathode should be and take into consideration C1's
rated voltage and maybe develop a Â*schematic in my head.

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Live Fast, Die Young and Leave a Pretty Corpse- Hide quoted text -

- Show quoted text -

Yeah I don't think that its a zener either. Its just that with the
cathode on + it doesn't seem like it could be forward biased so what is
it doing there? I haven't tried to draw it out but this otherwise
appears to be a straight forward 723 based linear regulator circuit. The
way this thing is built though its virtually impossible to reverse
engineer it. I do like your idea of using the variac for testing. I have
a small variac but with a small load on the PR60 ouput I don't think it
should be much of a problem. It ****es me off how uncooperative most of
these manufacturers have gotten in the past few years. Back in the 60's
when I started in electronics you could get anything from most anyone.
Today you would think I was asking for state secrets.This is an obsolete
model. What the hell difference would it make to give me a schematic?
Not like I'm going to try to mass produce these things. I would just
like to get it going for myself. Lenny

Years ago I bought a used Nady 201 that I wanted to switch channels.
Requiredan xtal change and some tweaking of the RF circuits for both the
xmitter and rxcvr. I finally got someone to talk to me at Nady. Even sent
me some schematics. I called back maybe 2 weeks later and that person was
no longer employed there. Seems at least back then it would take a
Wikileak to get any info from Nady. This guy probably got the boot for
giving me some tech literature. And Nady wanted back in around 1992 $69
+S/H to re-channel the 201. I had the info on the xtal parameters and
sent the data to Jan xtal. They made a new set of xtals for $14.99. Took
me 5 minutes to align. Still have the units.

Your diode might suppress some kind of transients in that config. May
help C1 live longer, hard to tell.


--
Live Fast, Die Young and Leave a Pretty Corpse