Re: [Amps] SB220 Meter blown...follow up hope

[Artek Manuals <Manuals@ArtekManuals.com>]

With nothing else to loose IT removed the meter and found that ther are 
TWO resistors inside. One is in parallel with the meter movement and the 
other is in series. Those both have been "toasted"  a bit it seems like 
the parallel one is about 15k and the series one is about 1.8k. The 1.8k 
is open.
Can anyone verify these values they dont appear on the BOM since they 
are internal to the meter itself
Obviously replacing these two resistors is going to be a lot easier than 
finding a replacement meter movement
Hellllpppppp!!!

Dave
NR1DX

On 5/15/2020 1:14 PM, Artek Manuals wrote:
> Comments below
>
> On 5/15/2020 12:13 PM, Jim Thomson wrote:
> > Date: Fri, 15 May 2020 11:10:06 -0400
> > From: Artek Manuals <Manuals@ArtekManuals.com>
> > To: "amps@Contesting.com" <amps@contesting.com>
> > Subject: [Amps] SB220 Meter blown
> >
> > <I am resurrecting a SB220 that had an apparent classic Grid/plate short
> > <event. One of casualties appears to be the right hand meter movement.
> > <This is the one for Grid Current and HV. I am pretty far into it and 
> > the
> > <meter movement measures open , the internal shunt resistor is blackened
> > <( and open?)
> >
> > <Anyone got a surplus movement from a parted out unit? Nothing found on
> > <evil-bay at the moment
> >
> > <Dave NR1DX
> >
> > ## I believe harbach sells replacements. The heathkit shop might sell 
> > em.
> They only have "meter diode/ resistor boards" no actual meter movements
>
> The rest below are all good ideas but moot if I cant find a meter 
> movement, Nothing in my manual says what the actual values of the 
> movement is either 8^(
> > Next time be sure to install rvs connected 6A10s or 1N5408s between
> > B- of hv power supply caps..... and chassis. HV fuse, followed by 50 
> > ohm glitch resistor is series
> > with B+.
> >
> > ## Toss all the grid chokes and caps. Bond each of the 3 x grid pins 
> > directly to chassis
> > with strap.
> >
> > ## Install a 2nd HV fuse...in series with one leg of the plate xfmr 
> > secondary....either leg.
> > ## Ok, now there is no way to blow anything up..including meters. Cro 
> > bar anything u want,nothing happens
> > except for a blown hv fuse.
> >
> > Jim VE7RF
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com


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