[TriEmbed] Substitute transistor

[Jeff Davies]

I'm ot sure if this is helpful because I can't see any of the original
attachments. What does your display look like?

Is the problem similar to this?

If so, the problem is the display. The Keithley 2110 VFDs go bad with age
and I suspect other displays can suffer the same fate. The fix was always
to replace the display like this guy covers: https://youtu.be/wXQdo42C6pE

On Sat, Jan 15, 2022 at 1:25 PM The MacDougals via TriEmbed <
triembed at triembed.org> wrote:

> The display blinked back on at full intensity for a short while yesterday!
>
> I believe it is the back light of the LCD that is the issue.
>
>
>
> ---> Paul
>
>
>
>
>
>
>
> *From:* TriEmbed <triembed-bounces at triembed.org> *On Behalf Of *The
> MacDougals via TriEmbed
> *Sent:* Saturday, December 18, 2021 3:02 PM
> *To:* triembed at triembed.org
> *Subject:* Re: [TriEmbed] Substitute transistor
>
>
>
> I replaced the transistor with an exact match from ebay and a couple of
> electrolytic caps (at Carl’s suggestion).
>
> The display is still dim.  Oh well.
>
>
>
> ---> Paul
>
>
>
>
>
> *From:* TriEmbed <triembed-bounces at triembed.org> *On Behalf Of *The
> MacDougals via TriEmbed
> *Sent:* Friday, November 26, 2021 9:11 PM
> *To:* triembed at triembed.org
> *Subject:* [TriEmbed] Substitute transistor
>
>
>
> My microwave display suddenly went very dim.  I opened it up and found a
> discolored
>
> spot on a circuit board feeding the display (see attached image).  That
> component is
>
> marked B1238, so I assume it is a 2SB1238, which is obsolete.
>
>
>
>
> https://www.digikey.com/en/products/base-product/rohm-semiconductor/846/2SB1238/30307
>
> Medium power transistor( 80V, 0.7A) 2SB1189 / 2SB1238 Features 1) High
> breakdown voltage, BVCEO= 80V, and high current, IC= 0.7A.
>
> 2) Complements the 2SD1767 / 2SD1859. Absolute maximum ratings (Ta=25C)
> Parameter Symbol Limits Collector-base voltage VCBO −80 Collector-emitter
> voltage VCEO −80 Emitter-base voltage VEB O −5 Collector current IC −0.7 C.
>
>
>
> Anyone want to help me find a replacement?
>
> I dug through my Dad’s stash of old electronics and found a TIP30B, which
> looks like it might work.
>
>
>
>
>
> ---> Paul
>
>
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