I've rewired the socket and got confused by its RCA-ish color coding. and mixed up ground and signal connections. I thought capacitor and diode would save me, but seemingly they did not.
I've corrected the mistake - now I can hear loading from the PC loud and clear, but the Speccy just ignores it. Occasionally the reaction to "initiation" sound is like that (not a regular equal red-blue pattern):
I'll update tomorrow (when I restore original connections), But I have grim feelings
In order to work out if you have damaged anything, we need to know what you had connected to your Spectrum. How it connected. And what else was connected to the items that are / were connected to the equipment that you had connected to the Spectrum. As that's a little confusing, I will give an example...
So here is a typical set-up with all the details:
1, ZX Spectrum,
2, TV,
3, Cassette Deck.
ZX Spectrum connected to the mains via a Sinclair power supply. Two wire mains lead (no earth),
ZX Spectrum connected to the TV via RF lead,
ZX Spectrum connected to the Cassette Deck via audio leads,
No other connections to the Spectrum.
TV connected to the mains. Two wire mains lead (no earth). Connected to the Spectrum as above. No other connections to the TV.
Cassette Deck connected to the mains. Two wire mains lead (no earth). Connected to the Spectrum as above. No other connections to the Cassette Deck.
With this example set-up, as there are no connections to mains earth, it does not matter if the audio leads between the Cassette Deck and the Spectrum are incorrectly wired, as the audio is an AC signal.
If you used the circuit schematic you posted earlier, and the Spectrum is being supplied by a Sinclair power supply, and the TV has a two wire mains lead with no earth connection. Then I don't think you would have caused any damage by having the audio lead signal and ground connections reversed. The resistors would have limited the current and the diode would have prevented the input (from the Spectrum's perspective) from going more than 0.7V negative.
So, the picture you posted. Was this taken after you corrected the audio lead error?
If yes, the ULA in the Spectrum is receiving the audio signal. But either the signal is distorted, or the level is wrong, either too strong or too weak. Do you hear any sound from the Spectrum via the TV during loading?
This YouTube video is a good example of a Jetpac loading (but keep in mind that it's not loading on a Spectrum +2)
! 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 in Somerset later in the year :)
Oooof. I have restored vanila schematics and managed to load Exolon from EAR-on-tape-head, wasting as little as two tries. ULA's alive!
However I can't see why I could not load directly, when I disconnected CASSETTE plug ans soldered the connection as below:
I don't know what was the issue. I could hear loading noises loud and clear, but ULA mostly ignored those, as if those were distorted.
Perhaps the diode was not 1N4148? It was a glass diode with "48" written on it. I have several ordinary grey diodes (without top voltage cutoff). Maybe I'll need to try one of those?
Here what it looked like when assembled:
What's my mistake?
I've tried several sources: Android TapDancer is simply ignored by the thing (a) when connected to tape head, (b) when connected through above mod and (c) when connected through earphones amplifier of home theater box. Windows loaders also do not work at all. Tap2wav output through VLC (a) occasionally works connected to tape head when volume is overdriven to 125% (b) does not work through above CASSETE connection mod and (c) unreliably works though home cinema amp headphones plug. OTLA does not work at all. Unconventionally encoded fast loaded games do not work at all. z802tzx output also is not accepted.
Come to think of it - my house is full of guff. I think I may dig up a pair of Target computer speakers I have not used since 1996. I guess I may get about 5W amplification from those. Though as far as I remeber - they succumbed to distortion. Need some digging.
Please pardon for disappearing. I've encountered a strange occurrence: It is called "life". I am not used to this "life" thing, I hope it shall not bother me this weekend.
On topic: Let me remind you that at the moment my Spekky is wired up like this:
I've dug up this old speaker:
It has an amplifier inside. Input is 3.5mm stereo, and it outputs amplified audio to a "slave" speaker via RCA.
For scientific purposes I've conjured up this thingumabob:
Connected my Speccy and started playing about with volumes that would reliably load games. The "reliable" volume, when output by the speaker is DEAFENING! My trusty analog voltmeter measures this (AC is uppermost scale):
I did not trust my eyes and rechecked it with a digital multi-meter: IT IS FOURTEEN AND A HALF VOLTS!
Is it normal? Could you please measure the AC voltage of your EAR connection?
I mean the amplification seems to be totally ridiculous.
Is that the voltage under load? (also that won't be an RMS reading)
The voltage is under load (hence that 3.5mm splitter).
The reading is averaged, but I believe it is close to RMS - the needle is not wobbling (uneven voltage is easily visible on analog devices). Also Spectrum's tape records are sinusoidal by design.
I see I have tired you. One more question: maybe it is C1815 transistor/amplifier part that is dead?
It could be quite possible that the voltage overpowers C319 and goes to the amplifier through all those resistors:
Naaaa!!! Just work and life getting in the way. Making hey while the sun shines (okay, cutting the hedge).
At the weekend, I will measure the AC signal level on the Ear input. Both with a couple of meters and a oscilloscope.
Highly unlikely the path shown in red on your second picture is being taken. As the top line between R313 and R306 is a filtered +5V supply line.
Also, note that transistors are fairly hardy devices when used in low voltage (lower than 24V DC) circuits, so although possible, it's not that likely that the transistor has gone faulty.
! 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 in Somerset later in the year :)
Sitrep. I've become absolutely desperate and have taken the Speccy to "repair everything" service center. The guys there stared at it for one whole day and returned it without even opening the lid. When handing it back they told me, that they did not dare to open the device, as all of the engineers are younger than the machine itself.
And whaddayaknow! After carrying the Speccy to the workshops and back under the rain, the bloody thing started working properly!
Both DataCorder and Ear-hack operate flawlessly! Now I am a proud owner of the most popular computer in history. Guys, thanks for your support. :)>-
! 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 in Somerset later in the year :)
Comments
I've rewired the socket and got confused by its RCA-ish color coding. and mixed up ground and signal connections. I thought capacitor and diode would save me, but seemingly they did not.
I've corrected the mistake - now I can hear loading from the PC loud and clear, but the Speccy just ignores it. Occasionally the reaction to "initiation" sound is like that (not a regular equal red-blue pattern):
I'll update tomorrow (when I restore original connections), But I have grim feelings
So here is a typical set-up with all the details:
1, ZX Spectrum,
2, TV,
3, Cassette Deck.
ZX Spectrum connected to the mains via a Sinclair power supply. Two wire mains lead (no earth),
ZX Spectrum connected to the TV via RF lead,
ZX Spectrum connected to the Cassette Deck via audio leads,
No other connections to the Spectrum.
TV connected to the mains. Two wire mains lead (no earth). Connected to the Spectrum as above. No other connections to the TV.
Cassette Deck connected to the mains. Two wire mains lead (no earth). Connected to the Spectrum as above. No other connections to the Cassette Deck.
With this example set-up, as there are no connections to mains earth, it does not matter if the audio leads between the Cassette Deck and the Spectrum are incorrectly wired, as the audio is an AC signal.
If you used the circuit schematic you posted earlier, and the Spectrum is being supplied by a Sinclair power supply, and the TV has a two wire mains lead with no earth connection. Then I don't think you would have caused any damage by having the audio lead signal and ground connections reversed. The resistors would have limited the current and the diode would have prevented the input (from the Spectrum's perspective) from going more than 0.7V negative.
So, the picture you posted. Was this taken after you corrected the audio lead error?
If yes, the ULA in the Spectrum is receiving the audio signal. But either the signal is distorted, or the level is wrong, either too strong or too weak. Do you hear any sound from the Spectrum via the TV during loading?
This YouTube video is a good example of a Jetpac loading (but keep in mind that it's not loading on a Spectrum +2)
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
https://youtube.com/watch?v=qUIv-A_DOc0
However I can't see why I could not load directly, when I disconnected CASSETTE plug ans soldered the connection as below:
I don't know what was the issue. I could hear loading noises loud and clear, but ULA mostly ignored those, as if those were distorted.
Perhaps the diode was not 1N4148? It was a glass diode with "48" written on it. I have several ordinary grey diodes (without top voltage cutoff). Maybe I'll need to try one of those?
Here what it looked like when assembled:
What's my mistake?
Android TapDancer is simply ignored by the thing (a) when connected to tape head, (b) when connected through above mod and (c) when connected through earphones amplifier of home theater box.
Windows loaders also do not work at all.
Tap2wav output through VLC (a) occasionally works connected to tape head when volume is overdriven to 125% (b) does not work through above CASSETE connection mod and (c) unreliably works though home cinema amp headphones plug.
OTLA does not work at all.
Unconventionally encoded fast loaded games do not work at all.
z802tzx output also is not accepted.
Come to think of it - my house is full of guff. I think I may dig up a pair of Target computer speakers I have not used since 1996. I guess I may get about 5W amplification from those. Though as far as I remeber - they succumbed to distortion. Need some digging.
On topic: Let me remind you that at the moment my Spekky is wired up like this:
I've dug up this old speaker:
It has an amplifier inside. Input is 3.5mm stereo, and it outputs amplified audio to a "slave" speaker via RCA.
For scientific purposes I've conjured up this thingumabob:
Connected my Speccy and started playing about with volumes that would reliably load games. The "reliable" volume, when output by the speaker is DEAFENING! My trusty analog voltmeter measures this (AC is uppermost scale):
I did not trust my eyes and rechecked it with a digital multi-meter:
IT IS FOURTEEN AND A HALF VOLTS!
Is it normal? Could you please measure the AC voltage of your EAR connection?
I mean the amplification seems to be totally ridiculous.
What may be the cause of voltage reduction?
The reading is averaged, but I believe it is close to RMS - the needle is not wobbling (uneven voltage is easily visible on analog devices). Also Spectrum's tape records are sinusoidal by design.
It could be quite possible that the voltage overpowers C319 and goes to the amplifier through all those resistors:
At the weekend, I will measure the AC signal level on the Ear input. Both with a couple of meters and a oscilloscope.
Highly unlikely the path shown in red on your second picture is being taken. As the top line between R313 and R306 is a filtered +5V supply line.
Also, note that transistors are fairly hardy devices when used in low voltage (lower than 24V DC) circuits, so although possible, it's not that likely that the transistor has gone faulty.
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
And whaddayaknow! After carrying the Speccy to the workshops and back under the rain, the bloody thing started working properly!
Both DataCorder and Ear-hack operate flawlessly! Now I am a proud owner of the most popular computer in history. Guys, thanks for your support. :)>-
Glad that it is working.
There is at least three people in the U.K. that repair poorly Spectrums. Shout out if you need help in the future ;)
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)