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+2A: issue 1 no sound but better picture than issue 4?Hello everyone. I have a slight problem here and I am trying to figure out what could be wrong. :-( I have two spectrum +2A with two board revision…
... oscilloscope to check that the oscillator is running and that the ... -
+2A: issue 1 no sound but better picture than issue 4?Hello everyone. I have a slight problem here and I am trying to figure out what could be wrong. :-( I have two spectrum +2A with two board revision…
... oscilloscope to check that the oscillator is running and that the ... -
A tally on the number of successful builds of the Harlequin[SIZE=4][COLOR=Green][U][B]A tally on the number of successful builds of the Harlequin.[/B][/U][/COLOR][/SIZE] Please post your successes below :-) …
... free (non connected outputs of AD724).
It's described ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
Yep, no need to set PAL/NTSC jumpers as the appropriate options are already linked on the PCB.
Silly question - is the AD724 soldered in the right way round, and free of shorts between pins?
B -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
Hi, Balford - the AD724 is mounted with the notch facing J9 as per Ingo's photographs. I shall check for shorts again now, but didn't find any last time... :) -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
can you make photos of top and bottom PCB of the section around the AD724 and show it here?
Ingo. -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... could send you a new AD724.
Removing the old one ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... .
It could prevent the oscillator from swinging on it's ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... the socket pole and the AD724 as I don't have ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... resolve a problem where the oscillator would not start at times ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... problems with some chips of AD724 to start-up oscillation. I ... the composite output of the AD724.
I would be ... -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
As I told before, I could send you a new AD724 (in an envelope) or you can send me the PCB for repairing it.
Greets Ingo. -
Possibly daft Harlequin composite question... :SHi; My Harlequin Rev. F works fine apart from one aspect: there's no composite out... :( I have checked continuity and the discrete components. I.…
... knacker the board desoldering the AD724.
I'll practice ... -
ZX81 and Analogue TVsI recently bought a really nice ZX81 on ebay in amazing condition, but I'm having issues tuning in an old analogue TV to lock onto the signal. I und…
... modulator has an analogue transistor oscillator that uses inductors and capacitors ... -
PlusDlite v2014.1 - problems with floppy power supplyI received a small batch of boards of the new PlusDlite design, which is similar to the original PlusD, with GAL etc. The main differences with the o…
...
2. Replace 100uF at oscillator circuit with smaller value, e ... -
A. Baldwin Dot Crawl SuppressorJust found this: [url]http://www.worldofspectrum.org/infoseekid.cgi?id=1000622[/url] What the heck was that modification...? :p It sounds good, bu…
... soldered in one of the oscillator circuits, thus shifting it's ... -
48K Issue 6A board only showing B/WI have a 48K Issue 6A board here, which only shows a B/W composite video signal on both, the modified RF-out, but also on the expansion bus (using my…
... result of a non functioning oscillator.
Oh, and the ... -
First attempts to obtain 10 channels (TS+GS)Just a curiosity but maybe several people could be interested. For some time now we make some attempts with Lord Vader, to force full synchronisatio…
... 128 shows 14.3 MHz oscillator (found on old PC boards ... -
Flickering RGB -> SCART output.Hello all, For my toast rack I have bought a [URL="http://www.ebay.co.uk/itm/Sinclair-ZX-Spectrum-128K-High-Quality-RGB-Scart-Lead-Video-Cable-TV-Le…
... thought about changing the crystal oscillator with a 18MHz one and ... -
Switched voltage regulatorIn the past a replacement voor the (hot!) 7805 has popped up a couple of times in various threads. As far as I know, Recom Power Inc. was always ment…
... too much noise from switching oscillator.[/QUOTE]
Yes, I ... -
Cooking toastrack... the dreaded smellI powered up my Spectrum 128 (heatsink model) yesterday only to see what looked like an out-of-tune picture on the television. I'm using a scart adap…
... a boost converter with an oscillator iirc.
You can ... -
Cooking toastrack... the dreaded smellI powered up my Spectrum 128 (heatsink model) yesterday only to see what looked like an out-of-tune picture on the television. I'm using a scart adap…
... not too high - otherwise the oscillator circuit stops oscillating and TR4 ... -
Cooking toastrack... the dreaded smellI powered up my Spectrum 128 (heatsink model) yesterday only to see what looked like an out-of-tune picture on the television. I'm using a scart adap…
So if TR4 keeps burning then it's likely the oscillator circuit has ... stopped oscillating? -
Cooking toastrack... the dreaded smellI powered up my Spectrum 128 (heatsink model) yesterday only to see what looked like an out-of-tune picture on the television. I'm using a scart adap…
... then it's likely the oscillator circuit has ... stopped oscillating?[/QUOTE ... -
ZX Spectrum+ video ? red on green problemThis is my first post on the forum, so let me introduce myself. I am retired for several years. For 30 years I have been a fan of the ZX Spectrum. I …
... 's caused by the system oscillator (14MHz) not being in sync ... machines by having a single oscillator and deriving both CPU and ... -
ZX Spectrum+ video ? red on green problemThis is my first post on the forum, so let me introduce myself. I am retired for several years. For 30 years I have been a fan of the ZX Spectrum. I …
... 's caused by the system oscillator (14MHz) not being in sync ... machines by having a single oscillator and deriving both CPU and ... -
Initial check - 128k ToastrackI was wondering if there are any guides to initial checks that can be performed on a 128k speccy (toastrack) before first power on? I've the excelle…
... the 48K machine, the same oscillator circuit is present to generate ... -
important Harlequin modWhile searching for a better solution for avoiding undesired spikes that corrupt the screen RAM at Harlequin I found a final solution. No additional …
... because inside the PAL coder AD724 the composite sync signal is ... -
ZX Spectrum issue 2 has only blue tintsRecently I've bought a 16k speccy and ran into some issues with it. Faulty keyboard, broken caps, no stable frequency, faulty lower RAM chip, it bein…
... is o.k. Check the oscillator and its frequency at pin ...
