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How the DC-DC converter worksI've not seen this before. The DCC-DC converter inside the Speccy has always been quite a mistery for me: [url]http://www.tablix.org/~avian/blog/arch…
I've not seen this before. The DCC-DC converter inside the Speccy has always been quite a mistery for me:
[url]http://www.tablix.org/~avian/blog/archives/2006/05/spectrum_dc_to_dc_converter/[/url]
Apologies if it's a double posting. :) -
ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
... checks before power on (continuity, tr4/tr5, coil, power connector) and the socketed ... -
Diag Board and Simple 8bit IDE IFHello, finally I have made it. After finishing Winston's Diag Board a few days ago I started yesterday building the 8 bit IDE Interface from Peras s…
... I got rid of this TR4/TR5/coil technique. But also there is ... -
ZX Spectrum 48K Issue 3, loss of -5V rail.Hi all, I've googled this problem and poured over the electrical diagrams for the circuitry concerning the power supplies and I believe I know what …
... ?
I noticed my coil does indeed a hissing noise ... />
I have not thouched TR4 or TR5 yet.
If ... that mean all the above (TR4, TR5, coil, diode) is in good working ... -
48k Spectrum "Jail Bars" Removal?Hi all Just curious I think I saw a post here about the bars that go down the screen on some 48k's I think he referred to them as "jail bars". Any…
... )
[*]Several kHz from the TR4/TR5/coil switching circuit
[*]Various frequencies ... smooth the outputs from the TR4/TR5/coil switching circuit would also help ... -
ZX Spectrum 48K Issue 3, loss of -5V rail.Hi all, I've googled this problem and poured over the electrical diagrams for the circuitry concerning the power supplies and I believe I know what …
... at one end of the coil will be the same as ... 12V DC). The voltage on the other end of the coil should ... issue boards, the internal voltage converter (TR4 and TR5) can fail and it ... likely that the internal voltage converter (TR4 and TR5) has failed.
'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... designed switch mode circuit (TR4, TR5 and the coil).
What I would ...
[*]Fit a second DC to DC converter to supply +12V for the ... &Ntk=gensearch&Ntt=DC+DC+converter&Ntx=mode+matchallpartial& ...Trying to repair a Speccy 48k - No PulsingI've had this machine for ages. I'd I've been putting off fixing it for some time now. So a couple of days ago I pulled it apart and started prob…
... current leaking through the coil of the DC/DC converter/inverter (TR4, TR5 and associated components ...ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
... start by testing all the DC voltage rails. And if all ... the DC voltages are okay, see if ... version of the DC/DC converter/inverter circuitry (TR4, TR5 and the "coil" and associated components ...what components normally get taken out if you plug+unplug a joystick interface in with the power onwhat components normally get taken out if you plug+unplug a joystick interface in with the power on? i remember doing this a few times when i had …
... kill TR4 and TR5, and maybe the coil (all part of the DC/DC converter/inverter ...Help changing TR4 and TR5Hi all! Please, help me! :) I think I'm not understanding the correct pins of TR4/TR5 and the transistors. So, if anyone know the correct pins, help …
... understanding the correct pins of TR4/TR5 and the transistors.
So ... and BC307 to use in TR4/TR5.
And I found some ... original pins that?
TR4 TR5 TR4 TR5
E C |\ /|
TR4/TR5 replacementHi guys, I've got another Spectrum I'm working on now - an Issue 4S this time. When I originally got it, I powered it up and did the basic tests a…
... I need to replace TR4 and TR5 in order to get ... I had some confusion with TR4. Looking at all the ... board. Photos show that TR4 should be installed in ... br /> I've since replaced TR4 (marked ZTX650) with a new ... I'm planning to replace TR5 later this afternoon.
...Broken ZX Spectrum? :(Hi! I bought a 2nd hand ZX Spectrum half a year ago. It worked perfectly fine when I first tried it. I put it back in its box which it was sent in, …
... 's caused by a DC-DC converter that uses TR4 and TR5. If you can ...Remove +12 Volt itemsWhich items can be removed on a ZX48K issue 4b PCB if I don't need the +12 Volt? Micky
... YUV to RGB or YPbPr converter.[/QUOTE]
I've got ... ) all the voltage conversion circuitry (TR4/5, coil, various diodes / capacitors etc ... , and it is 100% functional. :) DC input voltages from 10 to ... a ripple voltage on unregulated DC supply doesn't seem to ...Colour blocks on displayHi all, I have just acquired another Sinclair product, my first one being a C5, it's a 48K ZX Spectrum. It shows colour blocks on the display when p…
... to take DC meter readings within the voltage converter circuit. It ... that either the voltage converter circuit is faulty or ... concentrate on getting the voltage converter working properly and finally ... shorted its power connections, TR4/TR5 may die and if that ...Replacing coil with other component?The purpose of the coil transformer, from what I gather in the schematics of the issue 2 spectrum, is to create 5V from about 9-10V. Would it not be …
... /> Measuring the voltages at the coil with a DMM isn't ... want to verify whether the DC-DC converter is working you really ... d suggest connecting it to TR5's collector. On most Spectrums ... drawn). The issue 3b style DC-DC converter produces something closer to a ...Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... />
Transistors TR4 and TR5 are part of the DC-DC converter circuit that generates ...48k + Spectrum Issue 4S Display IssueHi all! Brand new user here. Growing up I had a zx spectrum for a little bit, and recently I have bought a working 48k + Spectrum (Issue 4). I was…
... things that can kill the DC-DC converter circuit), then it'll usually ... pass and you're sure TR4 and TR5 are good, then it ... check the diodes in the converter circuit and inspect the board ...ZX Spectrum 48K Issue 3, loss of -5V rail.Hi all, I've googled this problem and poured over the electrical diagrams for the circuitry concerning the power supplies and I believe I know what …
[QUOTE=Renegade;784026]Coil? TR4 or TR5?[/QUOTE]
Is the ... the voltage converter circuit is oscillating, then TR4 & TR5 are almost certainly ...Trying to repair a Speccy 48k - No PulsingI've had this machine for ages. I'd I've been putting off fixing it for some time now. So a couple of days ago I pulled it apart and started prob…
... . All measurement show that the DC converter doesn't work. Faulty IC ... GND and blowed the TR4 and possibly also TR5. Remove the hot ... chip from the board, check the TR4 ...48k Issue 6a Very sick indeed.Hi Guys. I have a 48k Issue 6a board that shows a white screen with grey border. The white screen has three black squares spaced equally on the le…
... are the "coil" (actually a small transformer), TR4 and TR5.
... kill TR4. Or kill TR4 and TR5. Or kill TR4, TR5 and the "coil". Also ... the prime suspects are TR4, TR5 and the "coil". Also check all ...
Once you have the DC supply rails sorted, plug the ...Finding a good (UK) external switch mode power supply for the basic 48k and 128k ZX SpectrumsThis idea has probably "done the rounds" by now . I think I have heard about it a bit late . This thread with look at replacing the original "heavy l…
... TR4, TR5, some new capacitors and a new voltage regulator (7805 or DC/DC converter ... regulator with a modern mini DC/DC converter module. Doing this significantly improves ...Modifying a speccy to +5v only operation.Just a thought experiment so far. Let's say i wanted to make a more resilient spectrum by getting rid of the DC-DC converter circuit. This would remo…
... LM1889 needs a +12V DC supply. Without a suitable ... with a regulated +12V DC supply. You can then ... to link the +12V DC input (previously the +9V ... the +12V DC rail once you remove TR4, TR5 and the coil.
... (nominal) and / or +12V DC happy.
There ...The Complete List Of The Causes Of Lower Ram Failure?Well the aim is to get a comprehensive list.I ask this because I know very little about it . I know that failure of "power supply" related capacitors…
... , design limitation of the DC/DC converter circuitry, meaning application of ... [*] Damaged due to either TR4 or TR5 failing (including due to ... use of the incorrect polarity DC input voltage,
[*] ... input supply instead of a DC input supply,
[*] ...16pf Capcitors for C72/C73 issue 3b. Can I use 18pf?Looking at the service manual it states to use a 16pf ceramic disc capacitor in positions C72 and C73 on issue 3b boards. Is this very critical in bo…
... /> I do recommend bringing the DC/DC converter circuitry up to the last ... an old stock MPS2369.
TR4 should be either a ZTX651 ... (both still in production)
TR5 can be any small signal ...Correction of +2 hardware errorsThis is a collection of various pieces of information picked up from various places, including a lot from this forum. I have edited it and reworded i…
... errors:-[/B][/U]
TR4, TR5 and TR7 (all type 2N3904 ... they work correctly.
TR4 provides the composite video output ... 6 of the TEA2000).
TR5 provides the vertical Sync. (V ... that is connected with its coil parallel to the motor. Cut ...Almost no picture on a toastrack Issue 6UI?d need some help with a toastrack, that hardly shows any picture on both the RF and RGB. It?s totally distorted. I had this before and I remembered…
... and I remembered that replacing TR4/TR5 did help. However, this one ... transistors are located near the coil, so at a different location ...48k - Why Won't it Buzzzz?Hi WOS ;) I bought a load of Spectrum games off eBay and thrown in for good measure was a 48k 1984 Issue 6a circuit board that I was told was for sp…
... thinking along the lines of TR4/TR5 having been blown, so I ... a wire on the inductor coil was broken! So I desoldered ...Help request for an injured Issue 4A spectrumHi folks, I'm hoping to resurrect an issue 4A spectrum that has been in my hoard for a couple of decades since buying it for spares. Someone ha…
... had tried to instigate the DC-DC mod on it at some ... know), tested and replaced faulty TR4 TR5 and the 9v regulator. I ...Portugese SpectrumI've just acquired a Speccy 48K which states "made in Portugal" on the back. I thought Portugese "Spectrums" were actually some illegal copy of a Tim…
... longer had the coil... In my two models, the DC-DC converter oscillator is ...
