[NJARC] 3RP1 CR tube/Heathkit HO-10 Monitor Scope

[Scott Roberts]

Thanks John.

 Mention it AFTER I start why dontcha!... LOL... However, it has helped expose several defects with the unit: I found one resistor which had obviously overheated the wire next to it, as I found them welded together... I also found a broken(clean in half!) resistor in one spot, and a couple other things. I am just annoyed I forgot to order the 3 .22/600 caps I needed for it when I placed a large electrolytic order with Just Radios. (I can't use electrolytics in place of paper caps I'm sure...) I am also starting to swap in X-Y caps on the 120AC line on most of my machines. 

I found one problem with my shop: I have been getting bits together for so many different radios, I lost track of what goes to whom! So I spent last night after work sorting caps (mylar, electrolytics, and those little flat ones John likes to supply us with ;)) into little plastic buckets labeled for each radio. It is now a very organized little pile of caps :) I have about 6 radios/components & power supplies to recap!

Scott



--- On Thu, 8/13/09, John Ruccolo <jr6v6gt at yahoo.com> wrote:

> From: John Ruccolo <jr6v6gt at yahoo.com>
> Subject: Re: [NJARC] 3RP1 CR tube/Heathkit HO-10 Monitor Scope
> To: "NJARC Radio Club" <njarc at mailman.qth.net>, "Scott Roberts" <ng19delta at yahoo.com>
> Date: Thursday, August 13, 2009, 9:26 PM
> Hi Scott,
> 
> It's NEVER easy with you, is it? ;-)
> 
> Pardon the pun, but in the future you should resist the
> temptation to "re-resistor" a piece of gear. That HO-10 is
> fairly modern, and most if not all of the resistors were
> probably still good (within tolerance, or at least close).
> 
> Think about it -- you didn't "re-resistor" that 70-plus
> year old Hallicrafters SX-16, why do it to a piece of gear
> only half that age?
> 
> The more parts you replace, the better your chances of
> making a silly wiring error that can be *extremely*
> difficult for you (OR YOUR FREINDS) to catch. By all means,
> get rid if the paper caps. But resistors are usually
> presumed innocent until proven guilty.
> 
> 
> Folks, feel free to chime in.
> 
> 
> Regards,
> 
> John R.
> 
> 
> 
> --- On Wed, 8/12/09, Scott Roberts <ng19delta at yahoo.com>
> wrote:
> 
> > From: Scott Roberts <ng19delta at yahoo.com>
> > Subject: [NJARC] 3RP1 CR tube/Heathkit HO-10 Monitor
> Scope
> > To: "NJARC Radio Club" <njarc at mailman.qth.net>
> > Date: Wednesday, August 12, 2009, 1:22 PM
> > Just remember 
> > Reply = Poster
> > Reply All = Everyone
> > 
> >
> _________________________________________________________
> > Wow... Long Subject line...
> > 
> > Anyway, Simple question: First(as usual) the
> backstory:
> > 
> > I purchased the HO-10 scope with a couple known
> problems,
> > so I decided to follow advice from a guy who works on
> them
> > and not only recap, but re-resistor the whole item.
> No
> > problem, simple stuff. However, in so doing, when I
> went to
> > remove the CRT tube (3RP1) the base cap pulled off
> the
> > wires! It was held very tightly by the socket, and
> literally
> > pulled off the end: the adhesive had given up the
> ghost, and
> > they pulled free of the solder, or the very ends of
> the
> > wires came off.
> > 
> > So now I have an unkeyed tube with a bunch of good
> > condition wires, and a cap to refit.
> > 
> > Looking at the schematic, would it be correct to
> assume
> > that the only two wires I could read continuity
> between
> > would be the heater connections? I looked over the
> schematic
> > and found pins 5 & 11 were not used by the tube
> itself,
> > and I determined where the gaps between wires were
> spaced to
> > go to the pins on either side. I then looked at the
> line
> > burned into the screen, and determined orientation,
> and
> > checked alignment with the cap. It appeared to be
> correct,
> > and my thought was that I could confirm by checking
> > continuity through the heater, as it would be the only
> place
> > I would find it. I assembled the cap to the tube
> after
> > cleaning, fluxing & tinning the leads, just have
> to find
> > my Duco cement to glue the base.
> > 
> > Simply put, is my above assumption correct?
> > 
> > 
> > Thanks!
> > Scott
> >
> ______________________________________________________________
> > NJARC mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/njarc
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:NJARC at mailman.qth.net
> > 
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > 
> 
> 
>       
>