steve gates

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  1. Hi, Does anyone know where I can get another SW-1 main power switch for a DC300 part # 3584, or what you would recommend for a good substitute? Steve
  2. I have a DC300, one of the earlier ones w/o IOC LEDS but no front panel bias door. I am in the process of replacing the power caps and I was trying to confirm the mounting orientation of the big 13.5K caps as in which side does the + go? I believe I have it right as I made a note when I took the old ones out, but I would like to double check. I am not used to working on these wacky newfangled solid state amps where sometimes the plus goes to ground as opposed to tubes where negative always goes to ground as decreed in the Old Testament. Steve Please disregard, I done figgerd it out.
  3. You all got to remember that people reading this post are probably like me. I got my ebay DC300 and it looked like it had been in the bottom of a birdcage or in an attic for 10 years, so while you have it opened up and are chasing out the spiders with cans of air, you start looking at the old caps and other parts and then it starts, thinking "what if?"......... furtive late night newark/digikey searches....... looking at schematics on the can.....Then inevitably...... Late at night at bench..... (maniacal laughter)........(Flashing lightning/rectifiers)............(crash of thunder!!) ...."""" The Ultimate DC300 can be Mine! Mine! ... Mine!,.... I Tell You! """" " Real Men Solder Naked" (But of course only in a metaphysical sense, grasshopper) SG
  4. Hi, It's great for a newbie to get such a response! I did a parts search at Mouser Electronics for the D108 and 208's 1N270, and it came up with the Central CDSH270. The spec sheet says quote "that it brings the science of the 90's to vintage equipment" and also that it's a replacement for germanium 1N270 type units. Reading these forums, it seems like D108 and D208 can be weakened if the amp was abused in the past. steve
  5. I am going to assume you are referring to the two flyback diodes per channel D109/110 or D209/210 a 1N4003. It would be highly unlikely that these two Diodes have gone bad as they are not used all that much by the circuit and wouldn't be responsible for the sound being thing and week. This would most likely be caused by a transistor or a capacitor getting weak or going bad. As an FYI the 1N4003 flyback diodes, Crown Part Number C2851-1, are still available from our Parts Department if you need them. 5594[/snapback]
  6. I don't see any 22uF capacitors in my DC300A or on the schematics I have. There are 0.0022uF caps and there 25uF non-polar caps and there are .22uF but I do not see these "22uF's". Perhaps you have a different version of the amp than I? Maybe you are calling your large power supply caps 22MFD. That’s it, you Americans and your old nomenclature? Just kidding… we still have some of that here in Canada. I think it more universal to call them 22,000uF. I mention these caps further down in my post. One of the electrolytic capacitors at the top of the driver PCB has been known to cause problems. It is C5, 10uF radial lead electrolytic. There is an Axial 10uF beside it and you should replace that too. It is C4 but you should keep it at 10uF and raising the voltage of both of these caps is good as Bill says above, 160V to 200V is great. Predominantly the old models had problems with C5. These caps are filter caps for the Op Amp power supply and you can raise the value in capacitance and voltage for this one. The service bulletin from Crown stated that the caps were faulty from a supplier but it may have been specified at too low a voltage rating. If you have the amplifier open, the driver board off and you are servicing it, then for the love of XXX replace the ceramic disk capacitors with MKP, type caps. 200V rating will work nice. There are various ones like C7, C102, C202, C121, C221...that may be all of them, I think. If she's an oldie, you will have a heck of a time adjusting input and output bias with those old dirty potentiometers on the board. Replace them if you can and or clean them well. I have a friend in the UK selling industrial temperature uA739DC Op Amps in the ceramic package. They are not cheap but heck they are NOS inventory and have never been used. Drop me an email and I will hook you up with him. The power supply capacitors hanging off the back of the chassis could easily be replaced by calling Apex JR. and Steve will hook you up with some big caps for the mains. He has all kinds of stock. Google Apex JR. and when you hit his site look for the Hitachi caps as he has posted pics of them. Great Guy, Great Service! The DC300A is an audio classic! It is an iconic semiconductor amplifier. Perhaps the greatest quasi complimentary design ever made, at least it is the most famous for certain. Go buy one and restore it now before they cost $2000.00 broken on eBay. Preserve our Audio history! After a few key points of restoration, you may have a chance to hear what the original designers heard? Not the shrill tweeter squeaking amp we all heard while listening. What'd ya expect for an old bugger of an amplifier? It needs new parts to sound new again. I love my DC300A and I'll be cooking up number 2 this year and I can't wait. I hope to have the website looking like a real web site in a month or two and it should be a little interactive for visitors. I need a little more time. Cheers, Shawn. 5492[/snapback] Hi Shawn, Thanks for a great informative reply!! I appreciate all your information, as I have seen the pictures of your DC300 on the forum and it is outstanding. I hope mine comes out half as cool as yours did. As far as Canada goes, down here in Houston we live by the Red Green slogan "Duct tape, the handyman's secret weapon" The caps I am referring to are the 25MF nonpolarized C108, 208, 109, 209 radial cans on the main board. I could only find 22MF N/P so I wanted to know how critical the values were. With my limited knowledge, I don't want to get too wierd. I am going to do all the electrolytics and probably the film caps for sure and now with your advice I will have to get back to Mouser and/or Antique Electronics, Handmade etc, to get some more stuff! I went ahead and got the C1 and C2 caps from Crown Parts department, maybe they also have those diodes you mentioned. When I opened up my Ebay box and saw the amp, it was like seeing an old friend. I lugged many a rack full of these things in the 70's and 80's, we ALWAYS knew they were going to work no matter how they got bounced around. I had an amp rack fall face first off a 5 foot loading dock. Busted off all the rack mounts, bent some knobs etc... Stood it up, rolled it backstage, plugged the amps in and did the show. The amp is heavier than I remember Thanks, Steve Remember, "Real men solder naked"
  7. Thanks for your help! I was thinking probably just the electrolytics, maybe nichicon muse or black gates. What would you use for c1 and c2? I cannot find a 13.5k screw can anywhere, I think will go with 15k and find something that will fit. I think the sanganos on there are 2.5 inches wide. 5413[/snapback] The caps C1/C2 part number C3436-0 can still be purchased from our Parts Department. 5452[/snapback]
  8. Thanks for your help! I was thinking probably just the electrolytics, maybe nichicon muse or black gates. What would you use for c1 and c2? I cannot find a 13.5k screw can anywhere, I think will go with 15k and find something that will fit. I think the sanganos on there are 2.5 inches wide.
  9. A newbie question, I have a DC300A and I was considering replacing the capacitors. I downloaded the schematic and service manual off the website and was checking the values. There are some, such as the 25mf for example, that may prove troublesome to get. Are 22 mf close enough etc? Would there be any advantage to replacing the mica and ceramics with metallized film types? Any suggestions from the experts? I remember these from back in the old r&r days, my tech buddy told me they could be touchy as to device types and values. Thanks, Steve