hron61 Posted December 31, 2023 Share Posted December 31, 2023 First off I'm not good with electronics but I can solder like a mofo. I built these 20 years ago and they turned out wonderful. Haven't been ran for 18 years (life got in the way). I figured instead of spending 199.99 ea for a check up that I might as well start replacing all the caps and just get em done now so I won't have to worry about failures later on. Some of the exact caps are tough to find like the Xicons, Jensens and the Elna Cerafines for instance. I found most of the Solens and I think I found an Xicon that may work. It's in the power supply and the 2 factory caps are 10,000uf 10v electrolytic and the ones I found are 10,000uf 16v electrolytic, am I good to go with these? I'm thinking maybe keep the jensens in and upgrade the rest of the audio side only. Any ideas on what audio caps work well in these? 1 Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 31, 2023 Share Posted December 31, 2023 3 hours ago, hron61 said: First off I'm not good with electronics but I can solder like a mofo. I built these 20 years ago and they turned out wonderful. Haven't been ran for 18 years (life got in the way). I figured instead of spending 199.99 ea for a check up that I might as well start replacing all the caps and just get em done now so I won't have to worry about failures later on. Some of the exact caps are tough to find like the Xicons, Jensens and the Elna Cerafines for instance. I found most of the Solens and I think I found an Xicon that may work. It's in the power supply and the 2 factory caps are 10,000uf 10v electrolytic and the ones I found are 10,000uf 16v electrolytic, am I good to go with these? I'm thinking maybe keep the jensens in and upgrade the rest of the audio side only. Any ideas on what audio caps work well in these? The 16V electrolytics will be fine. Any higher voltage rated capacitor will work like say 50V ones as long as they are close to 10K ohms. A few ohms higher will work as well like say 12K ohms at a voltage of the original or higher. You would not want to go much higher in ohms for other reasons I will not go into now. As far as film caps they are probably fine and not needing replacement. The truth is film caps rarely if ever fail any more so than than a transistor. Changing film caps in the audio circuit from one brand to another will most always change the sound. Sometimes better sounding to you and sometime not so much. Many restorers of electronic equipment are adamant on not changing film caps wanting the sound the engineer thought best for his amplifier to remain. Parts Express sells different brands of film caps among other vendors if you do decide to change them out. 2 Quote Link to comment Share on other sites More sharing options...
hron61 Posted December 31, 2023 Author Share Posted December 31, 2023 On 12/31/2023 at 3:47 AM, henry4841 said: The 16V electrolytics will be fine. Any higher voltage rated capacitor will work like say 50V ones as long as they are close to 10K ohms. A few ohms higher will work as well like say 12K ohms at a voltage of the original or higher. You would not want to go much higher in ohms for other reasons I will not go into now. As far as film caps they are probably fine and not needing replacement. The truth is film caps rarely if ever fail any more so than than a transistor. Changing film caps in the audio circuit from one brand to another will most always change the sound. Sometimes better sounding to you and sometime not so much. Many restorers of electronic equipment are adamant on not changing film caps wanting the sound the engineer thought best for his amplifier to remain. Parts Express sells different brands of film caps among other vendors if you do decide to change them out. That's good news about using 16v caps. I'll order them tomorrow. As for the film caps thats good to know that they usually last for awhile. I really don't want to change the sound, when I listened to them back in 2003-2004 they sounded very nice and was happy with the sound they were making. All the Solen film caps I already found and ordered last night but they are exactly what are installed already, no changes there. Should have maybe posted this yesterday, but oh well. I will leave the Jensens alone, they are impossible to find anyways. Hopefully they have many more years left on them. Amps probably only have 100 hours on them total. All the caps look like new still. Would you have an idea of what I would replace the Elna Cerafine electrolytic caps with? Can't find any of those. Nichicon? Panasonic FR? Maybe. I lost 99.9% of my audio gear along with everything I owned back in the day, (divorce issues) Forte's included. But my tube gear stayed by my side thankfully. Even after I get the amps done I still have to make the power cords and the interconnects as well. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 31, 2023 Share Posted December 31, 2023 26 minutes ago, hron61 said: Would you have an idea of what I would replace the Elna Cerafine electrolytic caps with? Can't find any of those. Nichicon? Panasonic FR? Maybe. Even after I get the amps done I still have to make the power cords and the interconnects as well. I lost 99.9% of my audio gear back in the day. Forte's, included. But my tube gear stayed by my side thankfully. Electronic geeks do not fret over brands that much when it comes to parts. If Mouser or Digikey have them any they offer would be fine. Techs have their favorites naturally and mine are Nichicon. Temp rating determines quality so 105C should be better than 85C ones. Below is what Mouser have in stock on the value you are looking for with less expensive first. https://www.mouser.com/c/passive-components/capacitors/aluminum-electrolytic-capacitors/aluminum-electrolytic-capacitors-radial-leaded/?capacitance=10000 uF&termination style=Radial&voltage rating dc=16 VDC&instock=y&sort=pricing Quote Link to comment Share on other sites More sharing options...
amped Posted December 31, 2023 Share Posted December 31, 2023 Don’t know if this will complicate things but hificollective has some jensens: https://www.hificollective.co.uk/components/jensen.html Welcome to the rabbit hole Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 2 Author Share Posted January 2 Amped, I have looked at the new jensens. I think I will try some but they are now audio note branded. So more research is needed for sound and durability, as in leaking. Henry, nichicon is on my radar, besides temp what else should I be looking for, they have many to choose from. Sorry I havent been back to post but since I posted this thread, I have spent many many hours locating capacitors. Looks like the only caps I can replace for exactly the same brand are the Solens, which I did order. The Xicons and the Cerafines are no longer available. For the xicons I was trying to stick with the new but different same brand for replacements but cant seem to do it that way so I have to mix em a little bit. When I do find one that would work its out of stock. My luck. Couldnt fine one brand to get all I needed. Dont know if that matters. Dont know if its just the 300b amp that uses strange values but Its been a journey searching. One order is coming from the UK, one is coming from Canada and some from the US. The film caps I will try not to replace if i can help it, except some Solens which were replaced with same, I located them fairly easy. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 2 Share Posted January 2 3 hours ago, hron61 said: Henry, nichicon is on my radar, besides temp what else should I be looking for, they have many to choose from. I do not worry so much about brands of capacitors as long as the capacitor does the job. Here are some I would choose from if I wanted 105C Nichicon. Nichicon is considered some of the best in the electronic field. https://www.mouser.com/c/passive-components/capacitors/aluminum-electrolytic-capacitors/aluminum-electrolytic-capacitors-radial-leaded/?capacitance=10000 uF&m=Nichicon&maximum operating temperature=%2B 105 C&termination style=Radial&voltage rating dc=16 VDC&instock=y&sort=pricing I do not know how much you care to learn about capacitors and it gets to be a long journey but if you do care to click on the data sheet of one of the above capacitors and it will provide all the info a engineer or designer could ask for. The only capacitors that are going to affect the sound that much are the coupling caps between the stages. Have you found the schematic of your amp? The first place I look for schematic is here. https://www.hifiengine.com/ Give me some specific values and ratings and whether film or electrolytic and I will look and see what I would consider. A list would be appropriate. Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 2 Author Share Posted January 2 You are too kind sir. I do appreciate your help. I will try to learn about caps as well. May take me awhile to understand them. The link you sent are for radials, mine are axials. I wish they had a better selection as I would like to have some in the same brand as some are axial and/or radial. If you send your email by pm (if you dont mind) I have a build manual with the parts list including all the caps installed, I can send you the list page, and I have good pics I took of the guts that way you could see it in real time. I have the schematic also. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 3 Share Posted January 3 If you can make the radials work they will be fine and cheaper too. Done that way by the majority of restorers. But then there are some purist that want to keep the original look under the hood. Not me, electrons could care less. Mouser sells axials but they are not that many being used in new equipment, their largest market for electronic parts. PM is short for private message on this forum. Click on me in profile and send message. I am slow but will get back to you. Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 4 Author Share Posted January 4 Pictures of guts, parts list and schematic have been sent. Let me know if they are legible, I had to resize them a bit. Not really a visual purist, the sound is what I crave, but trying to keep it mostly what the designers created for these amps. I took a look at maybe replacing axial with radials and the would be too tall because of the bottom cover and there isn't any room to lay them sideways, its pretty tight. I have a lead on some of the original ones 10,000uf except they are 16v vs 10v and they are Xicon which is what Welborne supplied I think I will use them for now and I will keep on looking for an upgrade on them at a later date. I did find the Elna Cerafine 100uf 35v so I'm happy about that too. Almost have them all finally but the Jensens will probably stay for now also since they sounded great and when I do upgrade them I will look at a mylar guts inside of a copper shell type, we'll see. I just want to get them operating again, been 20 years. Quote Link to comment Share on other sites More sharing options...
Marvel Posted January 5 Share Posted January 5 I had a pair of Welborne 2a3 Moondogs. They were superlative amps. Kinda wish I had kept them, but they are gone and so is the money. Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 5 Author Share Posted January 5 When I bought them I Almost went with the Moondogs, I figured I would be safer with 8wpc since my main listening is rock music. Would love to hear some. The Laurels will be cremated with me and spread on Mt Rainier, well maybe only the walnut base parts. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 6 Share Posted January 6 If working when you last used 18 years ago the chances are darn good if you use a Variac and start them up slow like over a 24 hour period starting at 50VAC for 4 hours, 60 for 4 and so on. I bet they come up just fine. Do clean the tube sockets and pins in case they have oxidized. Caig Deoxit is all I recommend you use. 20 years is nothing to those components. Unlike the above poster the one thing I would replace are the Jensen PIO caps Paper in Oil caps built like those do not do well after sitting unused for 20 years. If they were Hermetically sealed it'd be different but they are not. To keep the sound the same as it used to be, find another PIO cap made today. Good Luck Craig 2 Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 7 Author Share Posted January 7 Makes sense. Is it safe to use a variac on an ungrounded outlet? My outlets are not grounded in this old house I rent. Will a GFCI outlet be good enough? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 7 Share Posted January 7 7 hours ago, hron61 said: Makes sense. Is it safe to use a variac on an ungrounded outlet? My outlets are not grounded in this old house I rent. Will a GFCI outlet be good enough? Actually a GFCI outlet is darn safe. 95% of the gear I work with have 2 pronged power plugs. I use GFCI protection... Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 7 Author Share Posted January 7 20 hours ago, NOSValves said: Actually a GFCI outlet is darn safe. 95% of the gear I work with have 2 pronged power plugs. I use GFCI protection... Thats good to know since I'm in the electronic learning phase. Here's a picture of the guts of one of them. Can anyone familiar with laurels point out what caps in the circuits they pertain to? As in filtering, output, etc. Since I can't read a schematic yet that would be a big help. 1 Quote Link to comment Share on other sites More sharing options...
amped Posted January 10 Share Posted January 10 (edited) I was using a GFCI -something like this on my VTA ST120: https://www.amazon.com/TRC-Southwire-14650013-6-120-Volt-1800-Watts/dp/B000XU5MEG/ref=sr_1_16?crid=1MR1T5P0YFFL1&keywords=gfci+plug&qid=1704928910&sprefix=gfci%2Caps%2C85&sr=8-16) All was well but I checked my wall current. I forget the amount and it was a bit high so I got one of those circuit specialists red 5A variable transformers and the instructions said NOT to use it with a GFCI so I quit using the GFCI. A reason wasn't mentioned nor did I ask but the voltage thing bothered me more. UPDATE: I found this on the website: "Please note that Variacs are not compatible with most GFI (Ground Fault Interruption) wall outlets. Because the load is very inductive, the Variac represents a fault and will cause the breaker in a GFI to trip." BTW, the analog meter on that "variac" is not accurate. Many people way smarter then me on here... Edited January 12 by amped New Information Quote Link to comment Share on other sites More sharing options...
Marvel Posted January 11 Share Posted January 11 Do you still have these: Quote Link to comment Share on other sites More sharing options...
hron61 Posted January 12 Author Share Posted January 12 The mono blocks? Yes. Aren't those schematics for the stereo version? Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 12 Share Posted January 12 On 1/10/2024 at 10:08 PM, Marvel said: Do you still have these: Marvel and other electronic geeks, is the top tube on the input a CCS? Looks to me like it is since the signal is tied to the cathode of that tube. Totem pole perhaps. I am too lazy to do research hoping more talented tube guys know without doing research. Pretty sure Maynard knows as well as others. Quote Link to comment Share on other sites More sharing options...
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