Not sure who Peter is but yes a 3055 will work fine. I have a few condor running 3055 for 10+ years now.
From AP&R. OK, good to know. I also just noticed a cap (C1) on the small 5V board thats the correct voltage at 16v, but the wrong uf at 220. Manual calls for 16v, 47uf.
this is normal ^^^
No, these are not equivalent. The 2n6055 is a Darlington with a gain range of 750-18000 the 2n3055 is not and has a gain range of 20-70 a very different part. The 2n6059 is a very similar part and makes a good substitute.
Just fyi, I ordered a couple NOS 2n6055's the other day just as spare but they'll take a bit longer to get here. The 2n6059's from APAR, I just tracked them & they're arriving Friday, I thought about just testing it with the other one for the sake of moving along but the location of it being that it's mounted on top of the P/S and how it goes through the 5v companion pcb underneath, figure I'll do it once with the 2n6059.
Lucky you. I had some minor renovations to do. Then again, others have done major overhauls, @CaptainHendry for example has an EPIC thread.
Interesting didn't know it was a Darlington. I must have mistaken I swear I have it on video working with a 2n3055 it's on my YouTube channel and it has been for years. I will try to find it later tonight but looks like I am wrong
When you design electronics you build in MARGIN to accommodate all the variability. This includes things like current gain saturation voltage, load range of the supply, operating temperature range etc. In your case it's possible the previous drive stage was near the max gain/current output vs the min, the game likely doesn't draw anywhere near the max current the supply is designed for maybe the 3716 you used was near the max gain etc. This could allow the 3716 to work by chewing up all the margin built into the design. This however does not change the fact that the 3716 is NOT a suitable replacement for a 6055. It's also why no one should ever use the fact that some random change to a circuit they didn't design happens to work because there's no guarantee that same change will work in all cases OR conditions.
i agree but there is at least one case of a 3716 working just fine for several years. i don't remember my original reasoning process maybe i was looking at the wrong schematic? i am referring to the version at which a 2n3055 is indeed used ( with the rest of the darlington on board) that being said this might put undue stress on the 723
, as a matter of fact, it's at about .5v now on the board, not 5v, tested it every way, crap! but hold on, because of the new caps now that were blown and most likely holding, maybe just a step forward.
Hmmm... if you are able to adjust the voltage unloaded and set it to 5V it's likely the 723 is working (but it could be the current limit part of the chip bad, it's just unlikely). At this point I would try and see if it's a power supply issue or something shorted on the CPU board. Couple options, if you have a large ~5ohm resistor you can use it to load the supply (5v/5ohm = 1A) and see if the supply is capable of delivering at least 1A. You need a power resistor for this at least 5W but 10W would be better. OR you can use your meter and measure the CURRENT being drawn by the board to see if it's loading the power supply. The current limit is set by the .18ohm resistor on the PS. If this resistor is significantly higher resistance the supply will limit much earlier. Keep in mind to measure current you put your meter in SERIES with the load (the board) and make sure to use the correct range and terminals on the meter.Ok, so with P/S out, removed the 2n6055, tested it but it's good, unscrewed the X-former and was able to get the 5v companion board in position to really look it over and interestingly enough I found some corrosion on the board behind 330uf cap. Although there wasn't visual damage from the top, it definitely leaked out the back. Confirmed when tested, has about 1/4 of it's capacity left, it's bad.
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Then proceed to check the other small 220uf cap to the left of it and that one tested completely open, shot!
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At this point, I carefully removed the corrosion from the pcb with a little vinegar, baking, soda, and a soft toothbrush, was able to clean it up pretty good, I don't believe these caps were ever changed so at this point with some bad and with it out? Decided it was the right thing to do was recap the P/S. I had ordered good quality replacements caps, even the large one's (not cheap) just in case so had everything ready to go. I replaced the 2n6055 with the 2n6059 since had the companion board out, tested the bridge rectifier but all 4 legs were good when I de-soldered it so left that alone. It's like new now:
View attachment 778757 View attachment 778758 View attachment 778759
From here I discharged the monitor, unplugged everything including the neck, fired up just the P/S with nothing connected, tested all voltages coming out of it down to J1 connector to the main PCB, everything is PERFECT, slightly higher than +25, -25, 5v, the 6.3 ac on the supply, everything. Able to adjust the 5v just fine with the potentiometer, stable.
Next, plugged in J1 on the main PCB, turned it back on, Got excited to see NO red light! BUT however, there's no 5v
I felt around on the main board, there's no chips hot or even warm. (All I have is the p/s connected to the main pcb) nothing else, no monitor, speakers, soundcard, nothing. It doesn't blow the 2 circuit breakers this way neither.
So let me know your thoughts? Here's what I'm thinking now since it's one of the only things left I didn't check with the P/S. There's a current limit circuit on there as @toledoflyer had mentioned earlier. It has a MC1723CL. It appears to be a voltage regulator too as I'm looking into it. What does it do? and HOW do I test it? Possible to probe it? If so I'd need specific directions on the correct procedure to do that please. Keep in mind that It's very hard to get in there while the supply is turned on but maybe possible if I'm careful, it's the one chip i haven't felt if it's hot, lol, but don't want to touch in there with my finger. It might be better to just replace it with a new known good chip?
View attachment 778764
Also, here's the specsheet on that voltage regulator chip and it's suitable replacements. If so, I would socket it and it replace it with best recommendation but would like to here opinions first, any other possible suggestions too. Thanks
Interesting.. so thinking the resistor test sounds a bit easier to start. I could use a white ceramic resistor, something like this? Have to check if have one. What do you think would be easiest way to connect and test it? I've never tried it. Maybe connect the leads of the ceramic directly to the J1 molex 5v and ground? set the meter to amps, plug the probe into the 10a max port and just measure it with clamps to see if at least 1amp? or am I missing something?
Ok, it sounds like this is something you haven't done before. To measure current with your meter you need to put in series with the board, that's more complicated than just loading with power resistors. Yes those white ceramic ones are typically what I use. The one you show is 10ohms, you can put 2 of those in parallel to get 5ohms. Then just connect them across the output connector on the power supply, one side to the +5 the other to a ground. Then power up the supply and measure the voltage across the resistor. If the supply is working ok you should see 5V and the resistors will start getting warm. (Since they are dissipating power)Interesting.. so thinking the resistor test sounds a bit easier to start. I could use a white ceramic resistor, something like this? Have to check if have one. What do you think would be easiest way to connect and test it? I've never tried it. Maybe connect the leads of the ceramic directly to the J1 molex 5v and ground? set the meter to amps, plug the probe into the 10a max port and just measure it with clamps to see if at least 1amp? or am I missing something?
Using the board to measure draw seems a little more complicated to me as never tried that either but I'm just noticing test points that might make it easier if I can figure out what voltage they're supposed to correspond to since they're not measuring correctly right now. There's 2 ground pins labeled GND and 3 test pins but the voltages aren't labeled, maybe they are listed in the schematics but then not sure where to break if necessary to read in series? Need a little more specifics with that on where to connect. Thanks
Yes, thank you for the explanation. I'm hunting around for some resistors like this, but so far I've only found 1 10w 600ohm resistor? I may have to order it.
