JL Sargent Posted June 21, 2011 Author Share Posted June 21, 2011 On the function generator, would a Simpson 420 do it? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 21, 2011 Share Posted June 21, 2011 Don't go to hog wild just yet. Make sure you can fit those transformers on that chassis unless of course you want to build an entire new amp. What is the height of that chassis (inside dimension)? Is it possible to lay down a 1 3/8" cylinder can on its side under the chassis? Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 21, 2011 Author Share Posted June 21, 2011 inside it's 1 7/16". Yes a 1 3/8"cylinder would go under the chassis. But that transformer is surface mount, right? I found what looks like a good price here. http://angela.com/hammondoutputtransformer1650f.aspx Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 21, 2011 Share Posted June 21, 2011 Yes the transformers are surface mount. That is a good price for that Transformer. You need to figure out if you have enough room for two of them... if you go to the hammond website you can find all the dimensions of the transformer it's basically similar in size to the large power transformer on the amp now. The 1 3/8" I was asking about is to upgade the power supply filter cans. I'd suggest buying JJ brand multi section cans from www.tubesandmore.com buy one dual 100uf/100uf @ 500V and one 50uf/50uF @ 500V also buy one matching mounting clamp. You will mount one above the chassis and lay one down under the chassis (apoxy it in place). Orange drop 716P will do fine. I'd use something a bit better but they aren't bad at all much worse out there. Capacitors will not have a huge effect on this circuit. But again before ordering anything make sure you have room for the transformers they are much larger then those boney things on the chassis now. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 21, 2011 Author Share Posted June 21, 2011 OK, I'll verify the trannys will fit at the Hammond site and if that's a go I will see about ordering some parts tonight. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 21, 2011 Author Share Posted June 21, 2011 OK, on the trannys I have two choices. As they are 2.5" x 3.5" I can rotate them 90 degrees from existing ones and they will go right down with no other mods. Or I can push the sectoral cap back 1" and they will go right down with end bells facing front of amp. Either way I believe it will work out. I have everything else orderd and will get these on the way tonight too. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 21, 2011 Share Posted June 21, 2011 Ideally you want the laminations on the output iron to be running opposite direction of the laminations on the power transformer. Quote Link to comment Share on other sites More sharing options...
artarama Posted June 21, 2011 Share Posted June 21, 2011 This is a great read guy's. Thanks! It is very cool to see the back and forth and generosity of knowledge and experiance. It is a treat to listen to people that know what they are doing! Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 22, 2011 Author Share Posted June 22, 2011 You're so right Artarama. Yes, right now just waiting on the parts orders at this point. I've been looking at this chassis and wondering if I made a mistake ordering all 1/2 watt resistors. It might get kinda tight on that narrow board. Also trying to familiarize myself with schematic to chassis relationship. Man, sometimes what looks real straightforward on the schematic might not be so in the chassis and this is a simple one! I'm gonna try to post a few pictures of my progress. First and foremost though, a good cleaning of my work area is in order. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 23, 2011 Share Posted June 23, 2011 Yea I've heard schematics called "electronic road maps" but they can easily get you lost if you aren't very careful. For a novice it's best to take a part out, confirm proper value and put a part in one at a time. 1/2 watt resistors should be fine to replace 1/2 watt resistors. never reduce the ratings of resistors or caps. Higher wattage and voltage ratings from specification are always a good idea. When possible I always use resistors at least double the required rating. If it requires a 1/4 watt I use a 1/2 watt, If it requires a 1 watt I use 2.... Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 23, 2011 Author Share Posted June 23, 2011 To be more specific I ordered 1/2 watt for all the existing 1/4 watt. I also ordered several extras so I can match those as suggested. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 23, 2011 Share Posted June 23, 2011 Hate to rain on your parade but from what I can see all the existing resistors on the tag board were 1/2 watt. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 23, 2011 Author Share Posted June 23, 2011 No problem. When you said "I'd replace R47, R48, R55 and R56 with 120K 1/2 watt minimum rating." I suspected the existing ones might be 1/4 watt so I went ahead and ordered 1/2 watt for all those resistors.Talking resistors, Of course I ordered 10 watt for the ones you specified as such. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 24, 2011 Author Share Posted June 24, 2011 Got the antique radio supply order in and in checking it I noticed a small error by me. Capacitors C54 and C59 are called out as 47mmf on schematic which I believe is the same as .047uf. I ordered .0047. So it appears I managed to move the decimal place one to the right on those two small caps. Guessing I'll get to try again on those. I just wonder if that difference would adversly affect the circuit? But hey, the rest of the order looks ok. No sign of the transformers yet. Hoping for first of next week. I'll go ahead and match my resistors and start installing these correct parts. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 24, 2011 Share Posted June 24, 2011 Actually 47mmf equates to 47pF in todays parts. The .0047uF is 10 times the value you need 4.7nF and yes it will have an adverse effect on the sound quality. What you want to get is a Silver Mica cap 47pF 500V Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 24, 2011 Author Share Posted June 24, 2011 Thanks Craig, I'm on it. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 24, 2011 Share Posted June 24, 2011 JL how long ago were you an electronics tech in the air force? Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted June 24, 2011 Author Share Posted June 24, 2011 It was just 17yrs ago. [] What you sayin......I'm rusty? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 24, 2011 Share Posted June 24, 2011 well maybe just a little [] Quote Link to comment Share on other sites More sharing options...
artarama Posted June 24, 2011 Share Posted June 24, 2011 I'll go ahead and match my resistors and start installing these correct parts. What do you mean by "matching" , why is this done? Is this kind of the electronic equivalent of measuring and matching the valve spring compression values when rebuilding an engine? Quote Link to comment Share on other sites More sharing options...
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