[Top] [All Lists]

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

Subject: Re: [Amps] SB220 Meter blown...follow up hope
From: Artek Manuals <>
Date: Fri, 15 May 2020 13:45:30 -0400
List-post: <>
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



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 <>
To: "" <>
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 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.


Amps mailing list


This email has been checked for viruses by Avast antivirus software.

Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>