Blackbird Posted June 11, 2019 Share Posted June 11, 2019 Hello! I am new here and I have a question. I have a pair of Moondog 2A3 monoblocks for over ten years and I love these Moondogs. Recently one of the Moondog has very low volume. I have replace brand new set of NOS tubes for both Moondogs. But I still have the same problem with the bad Moondog. I don't know how to debug tube amp. Can anybody tell me what is wrong with my Moondog? Is there anyone that can make both of my Moondogs good again? I can pay to have these Moondogs tune up and replace any necessary parts to be good as new again. Thanks. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted June 11, 2019 Share Posted June 11, 2019 Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 11, 2019 Share Posted June 11, 2019 I had a coupling cap go bad in one of mine. Volume was low , and turning up the gain the signal was badly distorted. I swapped cables, sources, etc., to make sure it was the amp. I had had them off for some time (months), due to selling off my la scalas. Took if to a tech very close to me, who is based out of the Western Electric building here. He went through them both, replaced the same cap in both. They are now within 1/2 db. He was impressed and told me they were up there with the new WE 300B amp coming on the market. It will be worth it to get them both gone through. Bruce Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 11, 2019 Author Share Posted June 11, 2019 I just tested the Moondogs earlier this morning and one Moondog produced no sound at all. The other one had lots of background noises and very little volume. So basically my Moondogs are dead. I don’t know anything about the circuits of tube amps. I am hoping someone can help me restore the Moondogs. Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 11, 2019 Share Posted June 11, 2019 Did you build them or buy them already put together? If already assembled were they built by Welborne Labs? I can send you the assembly manual w/schematic, if you need it. I gave the tech a copy when he worked on mine. I decided I didn't want to mess with them myself, even though I've worked on other gear before. Where are you located? Bruce Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 11, 2019 Author Share Posted June 11, 2019 I bought the Moondogs on eBay. I was told that they were built by Welborne Labs. I don’t know anything about tube amps or the schematics. I don’t even have the manual for it. I don’t want to mess with them. I just want to pay someone to restore them. The Moondogs were the best 2A3 monoblocks I have ever listen to before they went broke. Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 11, 2019 Share Posted June 11, 2019 I will send you the pdf of the builders manual sometime tonight. A printed out copy could possibly help a tech more quickly diagnose your amps and perhaps get them repaired more quickly. Time is money. You didn't say where you are located. We may be able to point you to a tech close by. My Moondogs were built from a kit. I am the fourth owner and have had them close to ten years. They are awesome and I won't be selling them. 😉 Bruce Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 11, 2019 Author Share Posted June 11, 2019 Thanks Marvel. I am located in Panama City, Florida. I don't want to lose my Moondogs. I have tried a bunch of tube amps but I always go back to the Moondogs. They are the pinnacle of a 2-channel sound system! Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 12, 2019 Share Posted June 12, 2019 I just sent a message with the assembly manual/schematic attached. Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 13, 2019 Author Share Posted June 13, 2019 I have been trying to find technicians that are proficient in tube amplifiers around my area but so far I didn't have much luck. I may have to send the Moondogs out for restoration. Do you guys have any idea how much it would cost to ship the Moondogs? Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 13, 2019 Share Posted June 13, 2019 You are a 6.5 hr drive from where I got mine worked on, but he's a bit expensive and slow. It took him about three weeks to get started on them... Do you stll have shipping boxes for them? Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 13, 2019 Author Share Posted June 13, 2019 Unfortunately I don't have the shipping boxes anymore. 6.5 hours drive is very long for me. I don't think I can do it. Quote Link to comment Share on other sites More sharing options...
Panelhead Posted June 13, 2019 Share Posted June 13, 2019 A guitar amp tech can trouble shoot with the schematic. A quick voltage check most likely will identify the issue. The is one big advantage of SE amps. Very simple circuitry. Quote Link to comment Share on other sites More sharing options...
joshnich Posted June 13, 2019 Share Posted June 13, 2019 10 hours ago, Panelhead said: A guitar amp tech can trouble shoot with the schematic. A quick voltage check most likely will identify the issue. The is one big advantage of SE amps. Very simple circuitry. Good call on the guitar amp tech. Here is a listing of techs some are in northern Florida. I would certainly want references but as panelhead indicated the moondogs are not complicated. https://el34world.com/service.htm 1 Quote Link to comment Share on other sites More sharing options...
Blackbird Posted June 14, 2019 Author Share Posted June 14, 2019 I think I found the problem to the dead Moondog. There are two caps that were burnt. One is a Solen Fastcap 10 uF 5% 630VDC Capacitor PPE-MKP-FC and the other is a Solen Fastcap 47 uF 5% 250VDC Capacitor PPE-MKP-FC. Do you think if I replace these two caps, it would be restored? I have not open the other Moondog that have a lot of static noises. Quote Link to comment Share on other sites More sharing options...
glens Posted June 14, 2019 Share Posted June 14, 2019 It might've been the caps just went bad, but just as likely, or more, something else made them die. A more thorough checkout should be in order. 1 Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 14, 2019 Share Posted June 14, 2019 C1 (10uF) is the first cap connected between pin 8 of you rectifier and L1, and C4 (47uF) is part of the AC/hum balance circuit. I would get with on of the tube guys thee in Panama City and see if they could look it over for other damaged parts. Can you post a good pic of the whole underside of the amp? Mine was built as a kit and wasn't the tidiest of jobs. Hopefully yours follows the layout more clearly so it will be easier for a tech to go through. Bruce Quote Link to comment Share on other sites More sharing options...
Panelhead Posted June 14, 2019 Share Posted June 14, 2019 You could locate Welborne Labs and have go over. Quote Link to comment Share on other sites More sharing options...
moray james Posted June 14, 2019 Share Posted June 14, 2019 38 minutes ago, Panelhead said: You could locate Welborne Labs and have go over. did a fast search thinking they were gone. Found this. Welborne Labs is no more RMSVOLT.COM (never heard of them before) has acquired the rights to the Welborne Labs designs: »welbornelabs.com Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 14, 2019 Share Posted June 14, 2019 They got into financial difficulty over family issues... Quote Link to comment Share on other sites More sharing options...
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