Re: SC502 With Display Issues

Dave Wise

Do you think [oscillation] could be an issue in the low power supply section?
It's a much-talked-about complaint. In this particular case, it's unlikely since the transistors in question only operate in unusual cases - power off and overload, respectively.
But since we're doing Component Engineering figuring out a suitable retrofit part, why not put in 100% effort? Do work you can be proud of.

Dave Wise
From: <> on behalf of Stephen via <>
Sent: Wednesday, August 19, 2020 10:00 AM
Subject: Re: [TekScopes] SC502 With Display Issues

On Wed, Aug 19, 2020 at 05:48 AM, Dave Wise wrote:

To replace 2N3565 in the SC502 power supply, BC639 is better than 2N2222A,
100MHz vs 300MHz. Under a dollar at Mouser. But the best choice is KSC1008.
It's only 30MHz - perfect to avoid oscillation - and even cheaper. Mind the
Ooh ok. Now I understand. You were talking about oscillation. This is the thing I didn’t grasp before from your previous post. Thank you for clearing that out. Do you think that could bean issue in the low power supply section?

On a side note, I’m trying to find parts that are readily available at my local shops because it’s just a 20min ride from my place.
And I know that if something fails, I can easily go and get them without having to order, and wait for (sometimes) a week to 10 days to get them. Yes, it’s terrible, I know.
BC639 is available. Not the KSC1008. I’ll try that.

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