Do SCRs go intermittent?

[Bill Bowden]

My space heater using 2 SCRs sometimes goes into half wave operation and the fan turns very slow or stops. Is it possible for one SCR to be intermittent?

-Bill

 

On Monday, January 13, 2014 6:31:41 PM UTC-8, Bill Bowden wrote:

My space heater using 2 SCRs sometimes goes into half wave operation and the fan turns very slow or stops. Is it possible for one SCR to be intermittent?



-Bill

Bad solder connections are far more common than intermittent semiconductors..

G˛

 

[Michael Black]

On Mon, 13 Jan 2014, Bill Bowden wrote:

My space heater using 2 SCRs sometimes goes into half wave operation and
the fan turns very slow or stops. Is it possible for one SCR to be
intermittent?

I doubt it. Anything's possible but once inside the actual SCR, I think if
one of the tiny traces breaks, it won't come back to life.

But since it's a heater, it likely draws a lot of current, and that
stresses things. The Mac Plus was notorious for a bad connection to the
horizontal deflection coil; I got mine when someone didn't want to spend
the money to replace the board, I just jumpered around the connector (that
was showing signs of burning).

So look at the connections around the SCRs, mayb even reheat the solder to
be sure.

Michael

 

[Jasen Betts]

On 2014-01-14, Bill Bowden <bperryb@bowdenshobbycircuits.info> wrote:

My space heater using 2 SCRs sometimes goes into half wave operation
and the fan turns very slow or stops. Is it possible for one SCR to be
intermittent?

a bad solder joint or a broken wirebond inside the package could do
that.

-Bill

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For a good time: install ntp

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[David Harmon]

On Mon, 13 Jan 2014 18:31:41 -0800 (PST) in sci.electronics.basics,
Bill Bowden <bperryb@bowdenshobbycircuits.info> wrote,
>My space heater using 2 SCRs sometimes goes into half wave operation and the fan turns very slow or stops. Is it possible for one SCR to be intermittent?

Much more likely for a connection, like to a SCR lead, to be
intermittent.

 

[Maynard A. Philbrook Jr.]

In article <795966eb-f824-465d-be52-c806175ac671@googlegroups.com>,
bperryb@bowdenshobbycircuits.info says...

My space heater using 2 SCRs sometimes goes into half wave operation and the fan turns very slow or stops. Is it possible for one SCR to be intermittent?

-Bill

It sure it however, you could have a sagging line on one half of the
sine.. something else using half wave rectification... just a thought..

Jamie

 

[defaullt]

On Mon, 13 Jan 2014 18:31:41 -0800 (PST), Bill Bowden
<bperryb@bowdenshobbycircuits.info> wrote:

My space heater using 2 SCRs sometimes goes into half wave operation and the fan turns very slow or stops. Is it possible for one SCR to be intermittent?

-Bill

It could also be a triggering problem.