Rasterlist Archives: RE: Breakout PCB & Motorola monitor

From: Paul Sommers <Paul.Sommers_at_cwo.com.au>
Date: Sun Sep 24 2000 - 23:15:51 EDT

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<TITLE>RE: RASTER: Breakout PCB & Motorola monitor - questions for everyone!!!!</TITLE>
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Thanks Rodger.

I'll clarify a little further.

 
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I have now replaced the transformer with two others (one for 110vac and one for 16.5 and 6.3 vac). At this point we will assume he means the GAME transformer and not the monitor transformer---only way the voltages make sense. 
 
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Breakout had one transformer providing all voltages. I have replaced that with two transformers - one for the game board and one for the monitor.
 
 
 
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Leave the monitor alone for now, unless it has the waves while set for gray with the game board unplugged.á Leave polyester capacitors alone unless you know for a fact they're bad.á It's unlikely they are a problem. 
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Darn! Didn't look with the board unplugged! I'll try that tonight. That'll isolate it! Thanks!

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áá 
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3. While we're on caps. The big 8000uf at 16v that is one the board looks pretty old. But the only 8000uf cap I can get in Australia is 80v and it is a surface mount. What a pain - not to mention expensive. Can I put a couple of lower value caps which make up 8000uf in series or parallel instead???  Sure.á Or use a 10,000.á Or a 20,000!á Whatever you can find.á Or just try tightening the terminal screws on the one you have and see if that helps.

The 8000uf at 80v won't fit on the board (the one that is their is surface mount) so I'll get a couple of big ones in series - that should do it. BUT, before we get too carried away with this, I have a question.á Is there ONE hum bar or TWO?á Very simple rule here:

Imagine a grayscale light to dark - then put another on with the light side butted to the dark edge. There is no break - it just keeps coming. It's a vertical monitor - so it is going across the screen(or down/up if it was horiziontal). I guess if two hum bars mean a filter cap problem - 8 could mean a bad filet cap problem.
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á 
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5. I'll work this last one out eventually.... I have only half a brick in the first column (left hand side). Just thought someone may have seen this before. Monitor adjustment?á If I remember correctly, Breakout had the monitor turned so this would be a vertical adjustment.á OR that side of monitor is squashed (ala Nintendo games) due to open electrolytic in power feed of vertical output stage. 
 
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Sorry - I should have been clearer. The monitor is fine - the game board is not drawing half a brick for the whole row.

I think I'll cap the whole game board tonight and see what if anything that clears up. I'll also see if I get waves with the board unplugged.

Thanks
 MacMan

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----------
 From:   Rodger Boots
 Reply To:       rasterlist@synthcom.com
 Sent:   Monday, 25 September 2000 12:29
 To:     rasterlist@synthcom.com
 Subject:        Re: RASTER: Breakout PCB & Motorola monitor - questions for everyone!!!!

OK, let's take this one question at a time.

Paul Sommers wrote: 

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á

Gang,

The sad history of my Breakout is that the transformer caught on fire about a year ago (smoke everywhere - the fire brigade actually turned up because I opened all windows and doors for the smoke to get out).

I have now replaced the transformer with two others (one for 110vac and one for 16.5 and 6.3 vac). 
 á

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At this point we will assume he means the GAME transformer and not the monitor transformer---only way the voltages make sense. 
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á 
 It looks like the board got spiked because it was working fine to that point - now I have monitor and board problems that I've got some questions about.

1. I have replaced all the lytics on the monitor board, and it made no difference. I'm getting continuous waves through the picture. I don't believe they are hums bars. Just waves of greyscale. If you adjust the brightness and contrast to SOLID black and white - it is almost un-noticable. The waves move across the vertical screen right to left.

There are an awful lot of polyester caps on the board. Very old. Should I replace these or look for something else. 
 á

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Leave the monitor alone for now, unless it has the waves while set for gray with the game board unplugged.á Leave polyester capacitors alone unless you know for a fact they're bad.á It's unlikely they are a problem. 
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á 
 The thought has occurred to me it may be coming from the PCB. 
 á

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Either that or the power supply. 

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á 
 2. There are three caps of 50uf. The schematic lists these are polyester, but these look lytic. It doesn't look like a repair - or it was done long enough ago all the solder matches.

I can't find 50uf caps anywhere in Australia. How would I go with 47uf. Just how much tolerence do these things have.

Should I follow the original schematic and change them back to poly's. 
 á

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47 would be fine.á Tolerance on electrolytics (unless marked otherwise) can be as drastic as -20% to +100%.á But I doubt these are your problem. 
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á 
 3. While we're on caps. The big 8000uf at 16v that is one the board looks pretty old. But the only 8000uf cap I can get in Australia is 80v and it is a surface mount. What a pain - not to mention expensive. Can I put a couple of lower value caps which make up 8000uf in series or parallel instead???

á

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Sure.á Or use a 10,000.á Or a 20,000!á Whatever you can find.á Or just try tightening the terminal screws on the one you have and see if that helps.

BUT, before we get too carried away with this, I have a question.á Is there ONE hum bar or TWO?á Very simple rule here:

ááá ONE hum bar = bad rectifier (or fuseholder in series with rectifier) 
 ááá TWO hum bars = filter capacitor problem. 

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á 
 4. The paddle is shaky. It's okay when it is hard right, but as you move it further left you get very very shaky double and triple images. I'm wondering whether the main 8000uf cap which does the power filtering could cause this, as the paddle is the only part of the circuit (except sound... blip) that uses analogue components. I have replaced the 4016, 555 and the pot with no effect.

á

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Could be ripple doing this. 

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á 
 5. I'll work this last one out eventually.... I have only half a brick in the first column (left hand side). Just thought someone may have seen this before.

á

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Monitor adjustment?á If I remember correctly, Breakout had the monitor turned so this would be a vertical adjustment.á OR that side of monitor is squashed (ala Nintendo games) due to open electrolytic in power feed of vertical output stage. 
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á 
 Phew! It seems a lot, but I've brought it back from the dead and started getting tired of working it out myself. Hopefully someone can help me on one or more.

Thanks 
 MacMan

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-- 
 Windows:

32 bit graphical interface for a 
 16 bit patch for an 
 8 bit operating system written for a 
 4 bit processor by a 
 2 bit company that can't stand 
 1 bit of competition. 
 á

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Received on Sun Sep 24 20:43:49 2000

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RE: Breakout PCB & Motorola monitor - questions for every one!!!!