NOSValves Posted February 11, 2002 Share Posted February 11, 2002 Well the scott 222c overall has done well. But I've had some small bumps that I need help with. First off I have moved it into my basement for a 2 channel only setup (Wife insisted). Right now I have it hooked to a set of 1980 90+ DB fisher speakers. Actually it sounds real good with them. Okay now for the bumps.. Allan Songer was nice enough to send me some nice Amperex 7189s to try/buy since my outouts didn't match (3 tele 7189s and a USA 6Bq5. They did help out alot seemed much brighter with them and more detailed. Well while playing arround after putting the new ones in I turned the amp off and switched some inputs around and when I turned it back on I seen a flash coming from one of the tubes. Under further investigation I found the fuse blown so I went up to rad shack and bought some 2 amp slow burns and tried turn it on the rectifier tube started sparking inside not long after I turned it on and it blew the fuse again So I search around and bought a NOS Philips (mullard)5AR4/GZ34 brand new. So with my fingers cross I hooked it back up this time with a light in series to minumize the load. I read this trick somewhere and waited and it seemed to fire up fine played it for a while and then took the light out of the curcuit and it plays fine but ... Now the next bump I played it with a fm stereo tuner , 2 CD players and sent MP3's from my PC to it. I kept thinking man this just doesn't sound as good as before So I started really listening to it and started to realize that the problem seems to be coming from the right speaker. So I changed it to Mono and kept switching between left and right. Sure enough the right really seems to be somewhat muffled and dull compared to the left. I'm sure that it needs biasing or something. I noticed there 2 adjustable screws between the output tubes. I'm sure this is for left channel and right channel right ?? Help me out here I'm lost on this adjusting. Does it take a while for a brand new tube to brake in ?? What ya guys think ?? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 mdeneen yes I have the schematic for the unit. I don't have Vom but have access to one. You have to remember that these sparks and fuse blowing only happen when I turn the unit off and on real quick(I had been using the amp for weeks without a problem). I think it just over power a weak 40 year old Original Scott branded rectifier. It has been playing for 4 hours now with out any problem at all. My daughter is down there listening to her hip hop music I just told her to leave it below where is starts to sound bad. Also the 2 amp fuse is less than it really should have. I checked and it should have a 2.5 in it. I really think there is nothing wrong with the amp that tuning won't fix. I just don't know how to tune the power tubes. Can't is be done by ear ?? It just is not putting out ultra clear sound out of the right channel when played above 7 on the volume. Its not popping there no hisses nothing to suggest any real major problem. The unit is real nice inside all the parts look real nice no signed of age at all you would think it was built last week. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 How aboput if I email ya a real nice set ?? I can scan the one I have and blow it up for ya. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 Actually I just looked at the one I have and its pretty fuzzy. I'll go find ya a better one. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted February 11, 2002 Share Posted February 11, 2002 You cant set the BIAS by ear. IT is too fine an adjustment, and by the time your ear detected it, it would be SO grossly off that it would be unwise in all ways. Just go down to Radio Shack and pick up a meter but makes sure it reads lower enough for biasing. The lowest cost units dont measure in enough detail. Also, turnng the amp ON and OFF real quick should be AVOIDED! This puts tremendous strain on the tubes and circuitry, especially for an old amp. I try to wait a bit before turning a unit back on after powering down. In addition, always wait a few minutes before playing the unit when you first power it up. IF you think, remember when most light bulbs blow. When you turn them on! REcycling on and off and playing the unit right aways will shorten tube life. In fact, if playing a lot over the weekend, I personally would recommend just leaving the unit ON if it is running well. Most problems actually occur at power on and off. Treat the amp with care. Just based on your description, you are being a bit rough with it. Take it easy on the old beast. Treat it like a fine device... it aint no boom box, knowhatimsayin? kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 Do you happen to have any idea what might cause it ?? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 mobile homeless I know what your saying when it happened. I was all giddy because it sounded so well with the new tubes and a cheapo CD deck that I was in a hurry to get a better source hooked to it. Would you have any idea what would cause the slightly muffled sound out of the right channel. I just changed my right channel tubes back to the tele 7189s and its the same so that pretty much rules out the new tubes I would think. Can the bias adjust do it ?? Changing the tubes like this does require rebiasing right ?? Although I believe I read somewhere that bias is fixed on the 222c can't remember for sure ?? I also checked both channels with my DB meter and they both put out the same DB switching between them in mono. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 Here the schematic linkage http://hhscott.com/pdf/222C.pdf Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 Mdeneen thats sound easy enough and guess what ! I do have a meter in my garage I didn't remember my dad gave me 10 years ago. I do wish he lived nearer to me he knows all this stuff. When I get to doing it if I run into something I don't understand I'll just stop and post and wait for your reply. Now about your thoughts on it having another problem. I believe you are right. It has been play for 4 hours now and doing fine but there is a sound difference between channels my wife and daughter agree. Its not terible and barely noticeable when playing stereo at normal volumes. Now I have found another Clue. The Output transformer ( I think that's what its called one of the Iron units ?) the one for the right channel is running warmer than the left one again not allot but when holding your hand on it you can tell its warmer. None of the Iron runs hot to the touch you have to hold your hand on it hard for 10 seconds for it to get uncomfortable. Does this help you in any way ? Should I just recapp or rebuild the whole unit ?? I could buy all the parts and go to my dads and he would help me no problem. Is this most likely my best bet ? This message has been edited by NOS440 on 02-11-2002 at 09:27 PM Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted February 11, 2002 Share Posted February 11, 2002 Be careful in adjusting this DC Balance. If you ARE careful, it shouldnt be that big a deal. If you really want to keep this amp, get your Dad to help you perform some of these upgrades. While all might not be wanted, some of these look worthwhile and obviously increased the sonic performance - Take a look at this page and perhaps copy it. Then head to your Dad's after finding some good parts and get to WORK! I would have him go through it anyway but these mods like very tempting. See if you can email the guy for advice as well. Good Luck. http://www.teresaudio.com/haven/scott/scott299c.html kh ps - The Scott page also has information on setting Bias and the principals behind the different type of Scott amps This message has been edited by mobile homeless on 02-11-2002 at 09:50 PM Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 mobile homeless Thats a great read but for a 299c do the mods still apply ? Its a 7591 output tube Amp. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 11, 2002 Author Share Posted February 11, 2002 My dad would have no problem chasing down the problem I'm sure. He's 70 now so it might take him a while and I'm not a patient person LOL !! But I might just have to go up there and let him help me get started on it. As far as warmer its really not that much of a difference. Just thought it was weird that it was the same side that doesn't sound right. Are these HiFi rebuild kits worth the cheese and good parts or a waste of cheese ? http://www.vacuumtube.com/Products.htm##NEW%20Products Thanks for both of you guy's help you've been great Craig This message has been edited by NOS440 on 02-11-2002 at 11:08 PM Quote Link to comment Share on other sites More sharing options...
lynnm Posted February 12, 2002 Share Posted February 12, 2002 Your description leads me to look a little sideways at the filter capacitors in the power supply section. 1.)"Under further investigation I found the fuse blown" 2.)"problem seems to be coming from the right speaker" 3.)"You have to remember that these sparks and fuse blowing only happen when I turn the unit off and on real quick(I had been using the amp for weeks without a problem). A shorted filter cap WILL cause a massive amount of power to flow through the plate of a rectifier and result in overheating of the plate(s)and potentially/almost certainly allow massive amounts of unrectified power to be presented to downstream components. RE: #2 Most PS circuits are designed to recify the incoming AC power in full wave mode. Therefore should ANY filter Cap fail all downstream devices are at risk of being presented with voltages they are not able to deal with. Consider this: A tube circuit is designed to expect that at point A a maximum voltage of 350 volts,(with respect to ground) will be encountered - (The designer really only expects a max of 295 but he's leaving a little wiggle room).Some component,(more than likely a pair of PS Filter Caps take a dump)- (Domino theory #1 craps and the resulting surge kills #2 and both sides of that 295 sine wave head on down the pipe and the circuit designed to handle 350 volts D.C. gets whacked with the full voltage capability of the power tranny - probably something in the order of 450 volts AC. Both channels will likely take a hit but - Whichever of the channels is the more vulnerable in some way will potentially suffer more damage,(This applies whether the downstream is solid state or tube BTW and in fact Solid State devices are more vulnerable to this type of failure simply because an operating voltage variation tolerance of +/-1% in a 3.0 volt circuit results in an acceptble range of 2.97 volts - 3.03 volts. An equivalent tube circuit could absorb many times that variance in voltage based on the same ratio. The reality is that these ratios do not translate directly from solid state designs to tube designs but the principles do apply - If you need/want really accurate technical detail you will need to consult an expert. I am merely trying to explain the understanding/perception of one who is a pro in a related area,(Computers). ------------------ It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca.1900) Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted February 12, 2002 Share Posted February 12, 2002 NOS, Sorry for the 299 vs 222 confusion. I was in a rush looking around and mind went dead. Many of the same type of mods can be done to your unit though but there are differences. As for the PS caps, those are some of the first things I wouild get your Dad to replace with quality caps. Usually, however, when those go, you get a really noticable hum and you didnt mention that. Sounds to me like a combo of resistors and /or caps might be out of spec or gone south. This might sound dumb, but make sure your tone controls are even sounding...sometimes they can get off (and look same). At the very least, your Dad should replace the Power Supply Caps no matter what. Panasonic TSHB have a low ESR and are small enough to fit and sound pretty damn good. SPRAGUE is another option. For coupling caps, check out Auricaps...they cost extra but are very smooth. They arent too big either. Some of those mods on that page still apply in general. The ELNA cap mod in PS he did made a huge change...too bad you cant find them any more. See other tweaks that made a diff. kh ps- Should of bought an EICO...heh This message has been edited by mobile homeless on 02-12-2002 at 08:31 AM Quote Link to comment Share on other sites More sharing options...
Randy Bey Posted February 12, 2002 Share Posted February 12, 2002 Hey NOS, before you go in your amp fixing it up, can you put me in your will? Leave the amp to me Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 12, 2002 Author Share Posted February 12, 2002 Randy Bey LOL!!!!!! sure thing dude but don't count your chickens just yet. In my 42 years of piddling with every hobby you could think of I'm still here. mobile homeless I believe your most likely right and there's nothing really that wrong with the unit. Just some out of spec caps or something. Its funny that you mention the tone controls. I played with those last night and could even the 2 sides out to where I couldn't really tell the difference in channel at all. Its so hard to tell by ear when you have been listening to it for a while already. I just find it hard to believe that there anything all that wrong with it. It works perfect and at normal volume it sounds great it just gets weird when you push it hard. But I like to listen to my music loud . I realise I don't have much experience with this stuff but my guess is that some of the caps or resistors are slightly out of spec from age and the Original 40 year old rectifier just couldn't take it and went south when I did my stupid on/off stunt. If anything was real wrong with it. It wouldn't play for 6 hours lastnight without incident. Have any of you guy's checked out my Link to the rebuild Kit ?? This if worth the cheese would work out great for me because my did lives in northern michigan and if I go up there to start updating the out of spec parts it would be nice to have what I need with me even if I don't need it all ?? http://www.vacuumtube.com/Products.htm##NEW%20Products Thanks Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 12, 2002 Author Share Posted February 12, 2002 mdeneen I here what your saying. There mostly is something wrong with it. I just mean its not a real serious problem and I do plan to track it down. I'm going to bring this unit back to factory stock form and into spec. Its worth more in that state at least I think. I'm not going to go in and butcher the curcuits to make it sound better. No hot rodding on this one. I just want to make all it can be in its Original factory form. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 12, 2002 Author Share Posted February 12, 2002 I dropped VTC a line asking about the kit and available upgrades heres what they wrote back. What ya think of this. 1. The schematic is easy to read. Capacitors are all well marked and resistors have color codes. 2. The basic222C kit is $70 and includes all necessary parts under the chassis. The can type capacitors above the chassis and related under-chassis caps are an additional $130. The total kit minus tubes is $200 plus $6.00 shipping and handling. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted February 12, 2002 Share Posted February 12, 2002 The VTV kits are WAY overpriced for what you get. You can assemble the parts yourself and have better quality parts as well as better sonics. VTV has been so overpriced for what they offer. BAsically, they assemble the parts for you an charge for this. IF you pick better quality parts you will be much happier and will learn more as well. kh Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 12, 2002 Author Share Posted February 12, 2002 How the heck would I know what I need hmmmmm Well looks like the best thing to do is take the amp and Schematics to my Dads and diagnos what all I need on one weeked see what he has of these Items and then buy what's needed and go back up and finish it. I just hate to put it out of service for very long . Even in its less than optimal state it beats the **** out of my SS stuff. Quote Link to comment Share on other sites More sharing options...
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