Tpapp54321 Posted February 28, 2016 Share Posted February 28, 2016 Hello, I'm new to the forum and just bought my first project console, a colecovision. I set it up for a test run and literally NOTHING happened, the backround fuzz didn't even flick in the slightest. I'm not even getting a black screen. So my first thought was the power supply and after taking measurements I got the +5 and the -5 but got 0 for the 12. Is this the problem? Other then that I'm stumped. Btw my main hobby is repairing antique electronics and suck so I do have basic understandings of electronics, I just need to get a new soldering iron since my old one has a high change of damaging the circuit board. I really want to get this system running as I've always wanted a colecovision. -Tom Quote Link to comment Share on other sites More sharing options...
+5-11under Posted February 28, 2016 Share Posted February 28, 2016 Schematic, mostly correct: http://www.atarihq.com/danb/files/colecovision.pdf +12V for VRAM and Video, if I remember correctly. Quote Link to comment Share on other sites More sharing options...
7800fan Posted February 28, 2016 Share Posted February 28, 2016 The stock RAM chip uses all 3 voltages You can check it in case you didn't measure it right on the power supply, if 12v is absent, then the power supply is probably bad. Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted February 28, 2016 Author Share Posted February 28, 2016 So I guess it's most likely the power supply then, I guess I just expected something to happen when I turned it on. How do you guys recommend opening up these power supply's? Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted February 28, 2016 Author Share Posted February 28, 2016 Okay, I opened the power supple, I don't think the problem is cold connections. What do you think it's the problem? What should I replace while I have it open? -Tom Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted February 29, 2016 Author Share Posted February 29, 2016 Okay, I've decided that I'm going to replace the 7 electrolytic capacitors and the power transistor that is responsible for the 12 volts. Only problem is I'm not sure which one is responsible for the 12 volts... I think it's the one on the far right when looking at the power supply with the transformer at the top, could someone verify this? Second, what do I replace the possibly bad power transistor with (specifically model number of the part and where to get it) Lastly, where is the best place for electrolytic capacitors? Help would be MUCH appreciated, I'm just dying to get this thing running but need to first start with repairs to the power supply. P.S I also need a new soldering iron but have no idea where to start. I was thinking about getting this Weller: http://www.amazon.com/gp/aw/d/B00B3SG7F0/ref=pd_aw_sim_60_3?ie=UTF8&dpID=31xb1WHxcrL&dpSrc=sims&preST=_AC_UL100_SR100%2C100_&refRID=0ZY9PM84WBV19NCZQ76W Would this be a good soldering iron for working on small components? Quote Link to comment Share on other sites More sharing options...
BigO Posted March 1, 2016 Share Posted March 1, 2016 Okay, I've decided that I'm going to replace the 7 electrolytic capacitors and the power transistor that is responsible for the 12 volts. Only problem is I'm not sure which one is responsible for the 12 volts... My guess would be that it's the voltage regulator that's putting out zero volts. Honestly, I haven't been inside one of those CV power supplies yet, but here's a guy poking around in one that might be of some interest to you. Assuming they really are voltage regulators as stated in the video, checking input and output of those would be an obvious and easy place to start. Good luck. Quote Link to comment Share on other sites More sharing options...
coleconut Posted March 1, 2016 Share Posted March 1, 2016 Im just curious on how you opened the brick. Dremel, vise, hammer... Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 1, 2016 Author Share Posted March 1, 2016 Im just curious on how you opened the brick. Dremel, vise, hammer... I ended up just opening it with a hammer, it's a bit messy but I plan on cleaning it up later after the insides are fixed. My guess would be that it's the voltage regulator that's putting out zero volts. Honestly, I haven't been inside one of those CV power supplies yet, but here's a guy poking around in one that might be of some interest to you. https://www.youtube.com/watch?v=TfO1VFQBAvY Assuming they really are voltage regulators as stated in the video, checking input and output of those would be an obvious and easy place to start. Good luck. I ended up reading that these are actually power transistors not regulators, someone in the comments of the video said the same thing. Assuming that they are power transistors, where could I get replacements? Quote Link to comment Share on other sites More sharing options...
7800fan Posted March 1, 2016 Share Posted March 1, 2016 Look at the chip number. It may have company's name or logo and 2 lines of text. One of the line is usually date code such as 8212 (12th week of 1982) and the other number is what you would like to try and Google for it. Quote Link to comment Share on other sites More sharing options...
FABombjoy Posted March 1, 2016 Share Posted March 1, 2016 (edited) So I guess it's most likely the power supply then, I guess I just expected something to happen when I turned it on. How do you guys recommend opening up these power supply's? I'm a little late here, but I've used a hot wire foam cutter in the past. Take appropriate breathing precautions If you cut right at the seam, allow for about 5mm depth per side and the lid should come off fairly easily. The power supply uses regulator chips of type CA723CE Edited March 1, 2016 by FABombjoy Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 1, 2016 Author Share Posted March 1, 2016 I'm a little late here, but I've used a hot wire foam cutter in the past. Take appropriate breathing precautions If you cut right at the seam, allow for about 5mm depth per side and the lid should come off fairly easily. The power supply uses regulator chips of type CA723CE Okay, am I using regulator chips or power transistors? I keep on hearing one thing about them being regulators then another person says they are power transistors. I was pretty sure that were TIP41A power transistors as that's what it says on the body of the chips. Quote Link to comment Share on other sites More sharing options...
FABombjoy Posted March 1, 2016 Share Posted March 1, 2016 Okay, am I using regulator chips or power transistors? I keep on hearing one thing about them being regulators then another person says they are power transistors. I was pretty sure that were TIP41A power transistors as that's what it says on the body of the chips.Both: A low output regulator feeds a high output power transistor Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 2, 2016 Author Share Posted March 2, 2016 So should I replace both or just the power transistor? The electrolytic caps should definitely be replaced too, right? Quote Link to comment Share on other sites More sharing options...
FABombjoy Posted March 12, 2016 Share Posted March 12, 2016 Sorry for the delay, I don't get by here very often! If you haven't already done so and fixed things, you'll want to check the regulators and power transistors. Remember "garbage in garbage out" - measure the voltage coming in and what's going out at each stage. You have: Transformer windings Rectifier diodes Regulator Power transistor. At one of the components you'll probably find power in with no power out and that's your culprit! Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 15, 2016 Author Share Posted March 15, 2016 Okay, I just finished replacing all of the electrolytic caps and I also replaced the power transistors with no luck. This leads me to the regulator. How do I test to see if it's bad? Quote Link to comment Share on other sites More sharing options...
BigO Posted March 15, 2016 Share Posted March 15, 2016 Okay, I just finished replacing all of the electrolytic caps and I also replaced the power transistors with no luck. This leads me to the regulator. How do I test to see if it's bad? As a general statement, you compare the input voltage to the output voltage. Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 16, 2016 Author Share Posted March 16, 2016 How can I find the input and output voltage? Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 18, 2016 Author Share Posted March 18, 2016 Well, Today I decided to try to pinpoint where I was loosing the 12 volts in the power supply but in the process I shorted out the -5 volt power transistor. And this ones not a tip41a . I've already re-capped this and I also replaced the two tip41a's so I don't want to just give up and buy a new one but I'm starting to get quite frustrated with the one I currently have. Is there anyone that I could end up sending this out to? Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 27, 2016 Author Share Posted March 27, 2016 I'm a little late here, but I've used a hot wire foam cutter in the past. Take appropriate breathing precautions If you cut right at the seam, allow for about 5mm depth per side and the lid should come off fairly easily. The power supply uses regulator chips of type CA723CE Are both of the regulator chips CA723CE's? And does anyone know what the name of the of power transistor/regulator that is responsible for the -5. It's not a TIP41A is it? -Tom Quote Link to comment Share on other sites More sharing options...
FABombjoy Posted March 27, 2016 Share Posted March 27, 2016 Are both of the regulator chips CA723CE's? And does anyone know what the name of the of power transistor/regulator that is responsible for the -5. It's not a TIP41A is it? -Tom The -5 reg is a 7905 Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 27, 2016 Author Share Posted March 27, 2016 Thank you, just placed an order for some! Now I just need to figure out the other regulators. Quote Link to comment Share on other sites More sharing options...
thecrypticodor Posted March 28, 2016 Share Posted March 28, 2016 (edited) Thank you, just placed an order for some! Now I just need to figure out the other regulators. The other two aren't regulators they're tip41 power transistors. Make sure you re-use those mica isolation strips that the originals were mounted on. I once blew either one of transistors or the regulator (don't remember which one) by having the base of one of the tip41's in direct electrical continuity with the base 7905. Some CV PSU heatsinks I've seen are separated into two pieces, a revision I assume to further isolate the 7905. Edited March 28, 2016 by thecrypticodor Quote Link to comment Share on other sites More sharing options...
Tpapp54321 Posted March 28, 2016 Author Share Posted March 28, 2016 (edited) I saved the mica since I knew it was probably there to reduce the heat but when I took them out I lost almost all of the white paste that was sandwiched in between the mica and the components. What is this stuff? I'd like to add some more since it probably helped reduce heat. EDIT: also when I mentioned the remaining regulators I was referring to the chips not the two TIP41A's Edited March 28, 2016 by Tpapp54321 Quote Link to comment Share on other sites More sharing options...
BigO Posted March 28, 2016 Share Posted March 28, 2016 I saved the mica since I knew it was probably there to reduce the heat but when I took them out I lost almost all of the white paste that was sandwiched in between the mica and the components. What is this stuff? I'd like to add some more since it probably helped reduce heat. EDIT: also when I mentioned the remaining regulators I was referring to the chips not the two TIP41A's Sounds like typical heat sink compound which increases the ability of heat to transfer between the component and the heat sink. Messy stuff, but effective. When you open a tube of it, you can expect it to magically spread around the room and show up in places that you swear you never touched. It's like roofing tar in that respect, but it's white. There are probably numerous variants of the stuff, but here's an old standby: http://www.ellsworth.com/products/by-market/consumer-products/thermally-conductive-materials/lubricants-greases/dow-corning-340-heat-sink-compound-lubricantgrease-white-142-g-tube/?gclid=CIvo7qbb48sCFYJZhgod__oO9A (Aside: I also used this stuff to put some resistance back into my Atari 2600 paddles after a thorough cleaning by applying it to the rotary shaft/bushing. It certainly had the intended effect, though was a little too stiff for my taste so maybe I could have used less.) Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.