Replacement transistors for Spectrum +2 (grey)

Alex

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Sep 4, 2016, 5:48:16 PM9/4/16

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Hi,

I'm trying to fix a Spectrum +2, I suspect the transistors may be at fault and am looking to order some replacements. It seems the original transistors aren't used any more so I'm trying to figure out what the modern equivalents are there's guides for 48ks but not +2s, this is what I have so far:

TR1,3,6 BC239B/C549B - can't figure out equivalent
TR2 BC308B/C558B - can't figure out equivalent
TR4,5,7 2N3904 - 2N3904 - same
TR9 ZTX650 - ZTX651
TR8 ZTX213 - BC557

I'd be grateful if someone could fill the blanks and confirm my suggestions are suitable replacements.

Thanks
Alex

AndyW

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Sep 5, 2016, 2:44:59 AM9/5/16

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On 04/09/2016 22:48, Alex wrote:
> Hi,
>
> I'm trying to fix a Spectrum +2, I suspect the transistors may be at fault and am looking to order some replacements. It seems the original transistors aren't used any more so I'm trying to figure out what the modern equivalents are there's guides for 48ks but not +2s, this is what I have so far:
>
> TR1,3,6 BC239B/C549B - can't figure out equivalent
> TR2 BC308B/C558B - can't figure out equivalent

You can still buy BC239B
<http://www.cricklewoodelectronics.com/BC239B.html?gclid=Cj0KEQjwjK--BRCzv-Wyu4OTosEBEiQAgFp5OMdxHBFKt6nS8HWEpSEljI3gzLOIWMsm6VNvSL6PbYYaAsdt8P8HAQ>
And BC308B in ebay.

Andy

Alex

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Sep 5, 2016, 2:01:13 PM9/5/16

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Even easier, thanks I was looking on cpc. Were the other replacements suitable?

AndyW

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Sep 6, 2016, 2:15:57 AM9/6/16

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On 05/09/2016 19:01, Alex wrote:
> Even easier, thanks I was looking on cpc. Were the other replacements suitable?

Have you looked on Ebay for the originals? all the transistors are on
sale there.

The other thing to look at is to test the transistors; many inexpensive
multimeters have a transistor tester as standard.
What makes you think that it is the transistors to blame?
Generally on older technology the electrolytic capacitors drift with
age, that would be one of my first things to look at.

Andy

Volker Bartheld

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Sep 6, 2016, 2:47:59 AM9/6/16

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Hi!

On Sun, 4 Sep 2016 14:48:15 -0700 (PDT), Alex wrote:
> TR1,3,6 BC239B/C549B - can't figure out equivalent

https://www.buerklin.com/en/transistor/p/11s7000

> TR2 BC308B/C558B - can't figure out equivalent

https://www.buerklin.com/en/transistor/p/11s9750

> TR4,5,7 2N3904 - 2N3904 - same

https://www.buerklin.com/en/transistor/p/27s5200

> TR9 ZTX650 - ZTX651

http://de.farnell.com/diodes-inc/ztx651/transistor-npn-60v-2a-e-line/dp/9525572

> TR8 ZTX213 - BC557

http://de.farnell.com/diodes-inc/ztx751/transistor-bipolar-pnp-60v-2a/dp/9525629

At least that is what I get out of
http://www.8bit-wiki.de/index.php?id=3&filt=Sinclair/ZX_Spectrum/_zx48/manual/&cid=13597&mode=dl&tx=bd69aaf0000
and by comparing a few key features of those semiconductors.

HTH & Greets,
Volker

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@: W E B 2 0 1 6 at B A R T H E L D dot N E T
3W: www.bartheld.net

Brian Gaff

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Sep 9, 2016, 2:35:17 AM9/9/16

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In many cases, just first figure out whether they are pnp or npn and look at
the disipation. In many cases general purpose transistors used to work well
enough in many places, as I recall.

Obviously its been a long time and memories fad, but are you absolutely sure
transistors have failed, and exactly why they failed if they indeed have. I
know transistors are cheap but you really don't want to be fiddling about
unless you are pretty sure the fault that caused them to fail is no longer
present. Dodgy capacitors, etc. It is also a good idea to make sure the psu
is the right one and not faulty. The plus 2 had a voltage regulator inside
in a socket very prone to dodgy connections.
Brian

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