I think I may have broken the TR5 transistor in a +3 while doing the sound distortion fix mod (viewtopic.php?f=21&t=4666).
Is it possible to remove it and test it?
The only test equipment I have is this:
If so how would I go about testing it?
Many thanks!
Can I test a +3 transistor?
-
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Can I test a +3 transistor?
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Can I test a +3 transistor?
That meter will only test its hfe or gain value as explained at the link below but at least it will give some indication of its condition.
https://www.learningaboutelectronics.co ... transistor.
So find data sheet for given transistor then follow instructions attached below for that meter.
https://www.learningaboutelectronics.co ... transistor.
So find data sheet for given transistor then follow instructions attached below for that meter.
- Attachments
-
- test.txt
- (443 Bytes) Downloaded 65 times
-
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Re: Can I test a +3 transistor?
Thanks Moggy.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
-
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Re: Can I test a +3 transistor?
Either the transistor is completely dead - it reads 0 - or the legs are too short to engage with the testing mechanism.
I tried an unused BC549 and that gave a reading fine so the tester is doing its stuff.
I tried an unused BC549 and that gave a reading fine so the tester is doing its stuff.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Can I test a +3 transistor?
You can use the diode test range.
With a digital multimeter, the red probe is + and the back probe is -
A pass means a voltage of between 0.5V and 0.75V, a low resistance indication (but not less than 100 ohms) depending on the actual multimeter being used.
An open circuit means the meter showing OL, OPEn or other high resistance/open circuit indication.
A fail is anything else.
A resistance of less than 100 ohms means it’s fried…
For an NPN transistor:-
Mark
With a digital multimeter, the red probe is + and the back probe is -
A pass means a voltage of between 0.5V and 0.75V, a low resistance indication (but not less than 100 ohms) depending on the actual multimeter being used.
An open circuit means the meter showing OL, OPEn or other high resistance/open circuit indication.
A fail is anything else.
A resistance of less than 100 ohms means it’s fried…
For an NPN transistor:-
- Test between base (+) and the collector, should pass the test. Swap the leads around, it should indicate open circuit.
- Test between base (+) and the emitter, should pass the test. Swap the leads around, it should indicate open circuit.
- Test between collector (+) and the emitter, it should indicate open circuit. Swap the leads around, it should indicate open circuit.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
-
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Re: Can I test a +3 transistor?
Thanks Mark.
I ran the tests on a new 549C which obviously passed. The readings were around 810 on my multimeter (or 1 when open circuit).
I then ran the tests in my suspect TR5 and it gave readings of around 850 and then 1 when open circuit and therefore looked like it might be ok? I refitted it and still no sound.
I have sourced a 549B in case that makes a difference.
I ran the tests on a new 549C which obviously passed. The readings were around 810 on my multimeter (or 1 when open circuit).
I then ran the tests in my suspect TR5 and it gave readings of around 850 and then 1 when open circuit and therefore looked like it might be ok? I refitted it and still no sound.
I have sourced a 549B in case that makes a difference.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Can I test a +3 transistor?
Much to my surprise, I don’t have a BC549 or near relative in the bit box that I have to hand.
But I do have a couple of other ‘European’ NPN transistors to hand. Here are the results on two inexpensive multimeters.
Results will vary slightly between different transistor types, their gain, their current temperature and the meter used to test them.
Mark
But I do have a couple of other ‘European’ NPN transistors to hand. Here are the results on two inexpensive multimeters.
Results will vary slightly between different transistor types, their gain, their current temperature and the meter used to test them.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Can I test a +3 transistor?
BC549, BC549A, BC549B, BC549C are all the same specification transistor, except that the suffix (A, B or C) is indicating that they were tested by the manufacturer and sorted into gain (hFE in data sheets and data books) groups. The BC549 (no letter suffix) has not been sorted, or are actually BC549A. BC549C have the best (highest) gain figure.Lardo Boffin wrote: ↑Tue May 24, 2022 6:06 pm I ran the tests on a new 549C which obviously passed. The readings were around 810 on my multimeter (or 1 when open circuit).
I then ran the tests in my suspect TR5 and it gave readings of around 850 and then 1 when open circuit and therefore looked like it might be ok? I refitted it and still no sound.
I have sourced a 549B in case that makes a difference.
Hence a BC549B can replace a BC549A in most circuits (*) and a BC549C can replace a BC549B in most circuits (*).
I very much doubt that it will make any difference in a ZX Spectrum +3.
(*) I’ve yet to find a circuit where this is not the case, but there is likely an exception somewhere!
I’ve not read your other topic yet. When I have, I will reply there.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.