![]() Pay attention! the first two caps in the dog house are in series! Get that right or boom. ![]() Try and keep the exact values ie 25 not 22, 20 not 22 not because it matters one bit but if you sell it it implies hyper diligent restore to buyers that don't really know much, might force you to use spragues, supposedly they are nothing special these days, but again if you go to sell it'll look like it was a hot shit restoration to some people. You haven't played it in years so can't say where your ears are at, but some people freak after a cap change on an old but otherwise working amp that they are used to, they liked the dark soft sound, so give it a few hrs to burn in, then give it a few weeks of playing to break in, then live with it. If you want it to sound like when it left the factory you need to do all the bypass caps too, even if they are not totally shot it'll sound soft if you leave them, you'll hear it well enough once you change them, it'll really wake up. For now do only the electrolytics, filters and bias get priority, up the bias cap to 100V. w/o a variac you could use a light bulb limiter and just use a series of low to higher wattage bulbs for a few hrs each.ĭon't touch the blue coupling caps or the discs no matter how much you want to tweak, the blue caps are the mojo and pretty much irreplaceable w/o months of ebay searching. I'd install a temp fast blow B+ fuse too while doing this. A tech should do this though, if there are other problems, bad tube, bad bias, you need to watch the current and catch it as it comes up to full power. If you have any intention of selling it I'd leave it untouched and bring it up very slowly with a variac Geraldl Weber style, 40V for a few hrs then 10V per hr and try to reform the caps. Keep all the old parts, one day soon unmolested amps even non-working will be worth more than restored amps. That thing is pristine, please don't f#ck it up. I've replaced the filter caps under the sardine can on the other side. ![]() So I count five 25-25 and one 25-50 bias cap(which i will replace with 100 V). However I have yet to find the AB763 schematic/layout with the electrolytics highlighted, but from what I have now seen I'm getting more confident that I can figure it out. Sluckey I appreciate the post anyway.ġ0thTX, pretty much what I was looking for in the links. I've attached a photo of the "data sheet" affixed to the inside of the amp. I will drain those caps and work with one hand in my pocket. ![]() I am a DIY kind of guy and Im sure you all can appreciate the degree of satisfaction from fixing things yourself. Knowledge is the key and that is why I am here. As I am a novice at amplifiers, I do have the disipline from an BS degree in electromechanical engineering and a good amount of experience working on electronics to ensure good and safe practice. I do appreciate the concern regarding the high voltage and I am aware of the risks. I clearly joined the right forum - concern for safety is right up there with technical knowledge. Add to that the fact that you'll live another day to enjoy this amp, really, it's a good deal all around. The reason the job takes them 15 minutes and it takes someone else 2 hours is because they are entitled to be compensated for their competence, acquired through years in the trenches. Mostly, you pay the for what they know, not for what they do. Remember, sometimes you pay someone to do the work. When you can demonstrate you are more prepared for this, I feel certain you'll get help. There is a good sticky thread at the top of the technical section on materials to read. I'm saying you've got to educate yourself a whole lot more before sticking your fingers into a dangerous place. I'm not saying you can't or shouldn't do this on your own. For that reason, I expect you may not get a direct answer to your questions. ![]() As noted, this work can be lethally dangerous. Knowing what to do is not the same as knowing how to do it. Respectfully, the content of your post suggests you are not ready to do this work. ![]()
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