m_emelchenkov Posted April 28, 2019 Share Posted April 28, 2019 Hi! I have replaced all caps on my Vectrex MB. I have checked +5V, -5V and -13V, they seems OK. I have not tune high voltage yet, because awaiting shipment of a high voltage probe for oscilloscope. The "wobbling" problem still exists. Please look at the video. What do you think, where to dig next? Quote Link to comment Share on other sites More sharing options...
Zitruskeks Posted April 28, 2019 Share Posted April 28, 2019 (edited) To some extend I have the same issue, fully recapped late non buzz Vectrex, and especially the Focus and Distortion Test is very wobbly, too. Not that much like in your vid maybe and there is no wobbly vector in the integrator test like on your video. I can make a short vid at the end of the coming week, as I am not near my Vectrex atm. Can't really make a comparison to how she behaved before recapping, as I didn't have the test cart then and only brought her up for a short test of minestorm after an initial visual inspection. For me, its especially visible in the test cart and with spinball. Scamble and Minestorm feel ok-ish. I have checked and re-adjusted the HV, was sitting around 5.8KV - will do a fine tune again but i think it might not be the reason for the wobbles. Integrator Caps maybe? Yours is a buzzing Vectrex, so probably still the styrofoam caps on the integrator? Mine has the red foil (?) caps so i left them in place. Or maybe the wobbling of the whole image on the distortion test is normal?! Did you tune the DAC offset yet? EDIT: if i watch this video i see quite the same "wobblyness" as i expecience with my vectrex. So this might actually be normal, but on yours it is way worse. Edited April 28, 2019 by Zitruskeks Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted April 28, 2019 Author Share Posted April 28, 2019 (edited) Zitruskeks, mine looks not very bad at turn on and become worser after several minutes powered on. Not only wobbling but zoom in-zoom out picture. After recapping it become better, but still not good. Integrator caps were replaced too (I bought a full recap kit from Console5). When I asked about buzzing sound people told me it is OK for this model. Did you tune the DAC offset yet? Yes. If I did it right: I tuned it to the zero level with oscilloscope. Edited April 28, 2019 by m_emelchenkov Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted April 28, 2019 Author Share Posted April 28, 2019 (edited) Spinball on my Vectrex. Video does not reproduce wobbling very well, but wobbling is very high. Edited April 28, 2019 by m_emelchenkov Quote Link to comment Share on other sites More sharing options...
Zitruskeks Posted April 28, 2019 Share Posted April 28, 2019 I see what you mean, as said, i'll video my vectrex later this week. I also leveled the DAC offset with an oscilloscope to be as close to 0 volt as it can be, its a bit different on the later vectrex board, as there are now two seperate OP amp ICs instead of the dual one in the standard versions, but I have 0volt on both outputs. Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted April 28, 2019 Author Share Posted April 28, 2019 (edited) I have one dual amp. chip: LF353N. Edited April 28, 2019 by m_emelchenkov Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted April 28, 2019 Author Share Posted April 28, 2019 (edited) I looking at https://console5.com/techwiki/images/f/f8/Vectrex-Troubleshooting_Guide.pdf, Symptom "Picutre size changed and unstable when input voltage is normal". There is info that IC501 should have PIN 5 = 5VDC and PIN 8 = 3VDC. I have 5V on pin 5 but 12 V on PIN 8. Something wrong with the system? I looking at LM555 datasheet, its MIN voltage is 4.5V and MAX voltage 16V (it's supply voltage, pin eight). So, how could it be 3V? It simply will not work, if I understand correct. Also, waveforms of T502 pin 7 and Q502 base (pin 1 according to datasheet) should be the same. It is not. Here is a screenshot (blue is T502 and yellow is Q502). It was made not at Test #3, but as far as I remember it is the same in any mode. Waveform of IC501 in my board is 45 ms, not 50ms. Wrong? Can change it to 49ms using potentiometer (max position), and no change in wobbling issue. Also, I have a different input voltage: ~11.5 V instead 8.5-9V. I suppose it's due input voltage 250V instead 220V, and (maybe) not very good chinese AC transformer (I bought 220V 9-0-9 as a replacement to a dead original). However, I can say all these wobbling were with an old transformer too (it was a 220V model in 250V network). Any ideas what to do? Edited April 28, 2019 by m_emelchenkov Quote Link to comment Share on other sites More sharing options...
Zitruskeks Posted May 13, 2019 Share Posted May 13, 2019 Wasn't really able to film the wobble with my phone. Did you have any luck in the meantime? Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted May 13, 2019 Author Share Posted May 13, 2019 (edited) @Zitruskeks, yes, I think it is IC401, I checked its output with oscilloscope and it points out problems in this chip. I am awaiting shipping right now, in two weeks, maybe. Also possible cause is an over-voltage on +9/-9 lines (due the fact that instead 220V I have 240-250V)—I need to buy a voltage stabilizer to isolate this cause. Edited May 13, 2019 by m_emelchenkov 1 Quote Link to comment Share on other sites More sharing options...
R.Cade Posted May 13, 2019 Share Posted May 13, 2019 (edited) Let us know if you figure out how to stabilize it. Mine wobbles a little even after a cap kit, and many that I've seen at other shows wobble like mine. I think some amount is normal. How much, who knows? Edited May 13, 2019 by R.Cade Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted May 13, 2019 Author Share Posted May 13, 2019 I will write here after my experiment of IC401 replacement and stabilizing input voltage. Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted May 23, 2019 Author Share Posted May 23, 2019 I have replaced IC401. The wobbling now way less than before, but far from ideal. I also stabilised input voltage (not to 220V, but to 230V). Now I have some more ideas what to try, it will takes time though. 1 Quote Link to comment Share on other sites More sharing options...
R.Cade Posted May 23, 2019 Share Posted May 23, 2019 Now, they all wobble a little. This was a cost-reduced kids' toy, after all. I've never seen one that didn't wiggle some... Quote Link to comment Share on other sites More sharing options...
m_emelchenkov Posted May 23, 2019 Author Share Posted May 23, 2019 I think, mine one could be improved. I'll post here if I will have any success with it. 1 Quote Link to comment Share on other sites More sharing options...
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