It happened..
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- Location: San Francisco
It happened..
It happened.
I've crossed the Rubicon and now own my very first Spectrum.
Before I went looking to relive my childhood by finding and fixing a Ts1000, then finding this board, I'd never even heard of the Spectrum.
Now here I am
It came with another Ts1000 (my 4th) and a late 70's early 80's pong clone called a Glorytone (which I'd also never heard of).
I've got some fun learning ahead
I've crossed the Rubicon and now own my very first Spectrum.
Before I went looking to relive my childhood by finding and fixing a Ts1000, then finding this board, I'd never even heard of the Spectrum.
Now here I am
It came with another Ts1000 (my 4th) and a late 70's early 80's pong clone called a Glorytone (which I'd also never heard of).
I've got some fun learning ahead
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- Joined: Wed Apr 08, 2020 4:48 am
- Location: San Francisco
Re: It happened..
It turns out that the Spectrum+ is an issue 4s with a 6C001E-7 ULA
And I have no idea what that means
And I have no idea what that means
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- Joined: Sat Nov 26, 2016 2:42 am
Re: It happened..
Issue 4S means it was made by Samsung I believe. It also means the keyboard membrane may even still be working!
Some further info here http://blog.tynemouthsoftware.co.uk/201 ... r.html?m=1
Has it been recapped? Its unusual to be able to see all of the polarity and rating markings on the caps when factory fitted.
Some further info here http://blog.tynemouthsoftware.co.uk/201 ... r.html?m=1
Has it been recapped? Its unusual to be able to see all of the polarity and rating markings on the caps when factory fitted.
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: It happened..
Same issue as mine and as Lardo says, made by Samsung. The keyboard membrane tails on this one(unless replaced) are of the superior plastic type as opposed to usual "paper" ones of earlier issues.
The ULA I believe is the last of the line series wise though will obviously stand correction if in error.
The ULA I believe is the last of the line series wise though will obviously stand correction if in error.
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- Joined: Wed Apr 08, 2020 4:48 am
- Location: San Francisco
Re: It happened..
Thank you!Lardo Boffin wrote: ↑Fri Sep 04, 2020 8:47 am Issue 4S means it was made by Samsung I believe. It also means the keyboard membrane may even still be working!
Some further info here http://blog.tynemouthsoftware.co.uk/201 ... r.html?m=1
Has it been recapped? Its unusual to be able to see all of the polarity and rating markings on the caps when factory fitted.
The keyboard membranes are in fact in great shape
However, after doing a quick visual check and clean up with IPA I added power and got <drum roll> no signal
So, it looks like I have some fun ahead of me to fix my first Spectrum+
The linked article is a great start.
Thank you again
- 1024MAK
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- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: It happened..
Okay, please be clear on what you mean by “no signal”.
Some pointers:
If the Z80 is running (and the ROM, RAM and clock generator part of the ULA are working), then pressing a key (except one of the shift keys) should generate a keyboard ‘click’.
If the ULA has power and it’s crystal oscillator circuit is working, it will produce a video signal regardless of what the Z80 is doing (or not doing).
Loss of video can be due to the loss of the +12V supply (generated via an on board DC-DC converter from the +9V input. If this DC-DC converter is not running, there will also be no -5V bias supply for the 4116 (or equivalent) ‘lower’ DRAM chips. These really don’t like not having a -5V if the +5V and / or the +12V supplies are present.
So it’s always a good idea to test the +5V, -5V and the +12V supplies. Either on the 4116 (or equivalent) chips or on the edge connector.
The quickest way to kill a ZX Spectrum, is to apply a DC voltage to the power input with the incorrect polarity, or apply a AC voltage. The correct polarity for the 2.1mm/5.5mm mini power connector is: inside is negative and the outside is positive.
Fitting or removing expansions / interfaces while the computer is powered up can kill various chips. Or kill the transistors (TR4, TR5) that form the DC-DC converter.
One of the most common faults is failure of one or more of the 4116 (or equivalent) chips.
Mark
Some pointers:
If the Z80 is running (and the ROM, RAM and clock generator part of the ULA are working), then pressing a key (except one of the shift keys) should generate a keyboard ‘click’.
If the ULA has power and it’s crystal oscillator circuit is working, it will produce a video signal regardless of what the Z80 is doing (or not doing).
Loss of video can be due to the loss of the +12V supply (generated via an on board DC-DC converter from the +9V input. If this DC-DC converter is not running, there will also be no -5V bias supply for the 4116 (or equivalent) ‘lower’ DRAM chips. These really don’t like not having a -5V if the +5V and / or the +12V supplies are present.
So it’s always a good idea to test the +5V, -5V and the +12V supplies. Either on the 4116 (or equivalent) chips or on the edge connector.
The quickest way to kill a ZX Spectrum, is to apply a DC voltage to the power input with the incorrect polarity, or apply a AC voltage. The correct polarity for the 2.1mm/5.5mm mini power connector is: inside is negative and the outside is positive.
Fitting or removing expansions / interfaces while the computer is powered up can kill various chips. Or kill the transistors (TR4, TR5) that form the DC-DC converter.
One of the most common faults is failure of one or more of the 4116 (or equivalent) chips.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor 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 being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor 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 being good this year.
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- Location: San Francisco
Re: It happened..
Pretty sure I got that backwards last night.
I'm going to go *slowly* check traces and make sure I 100% know how power is getting to the 7805 before I plug it in again.
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- Location: San Francisco
Re: It happened..
It looks like I got super lucky
4116 chips show +4.88v, - 5.17, 11.88
I'm getting a good 4mhz oscillation at the ULA
TR 1 - base shows a signal
TR 2 - base did not show a signal
TR 2 - collector shows a signal
TR 2 - emitter shows a signal
I live in NTSC land. My TFT display auto detected a PAL signal but still gave a blank "No Signal" screen.
There is no composite mod on this machine yet.
4116 chips show +4.88v, - 5.17, 11.88
I'm getting a good 4mhz oscillation at the ULA
TR 1 - base shows a signal
TR 2 - base did not show a signal
TR 2 - collector shows a signal
TR 2 - emitter shows a signal
I live in NTSC land. My TFT display auto detected a PAL signal but still gave a blank "No Signal" screen.
There is no composite mod on this machine yet.
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- Posts: 122
- Joined: Wed Apr 08, 2020 4:48 am
- Location: San Francisco
Re: It happened..
This is the signal going into the RF modulator Which (to my untrained eye) looks a bit like a video signal.
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- Joined: Wed Apr 08, 2020 4:48 am
- Location: San Francisco
Re: It happened..
I think I've got some memory issues - but I've got signal!