Questions about tubes and gear that glows. FAQ
some things are possible some things are just flat out, out of range. I have a measuring subroutine constantly running in my head, comparing the possible and what's doable, weighing my current situation and the reality in front of me, it assess the situation and reports back the probability of success. Basically I am a newb at this vintage tube restoration stuff, but I am learning more. I am on my third restoration project, the two previous ones very successful. On this third project, all the kits are all available and well documented and supported from Jim McShane. The subroutine meter clicked off in my head and reported back that even though this would be the most complex restoration yet, that I still had a good chance of successfully completing it...
The project is a full Citation V restore, the whole 9 yards, Power Supply, caps resistors meter kit, basically everything Jim offers for the unit. I picked this amp up from a local studio, but it was not working (unlike my previous restores, the units were at least running before I restored them..note this factoid for later on...) I began the project with pencil and paper for a few days planing every step making notes and drawing sketches of what I interpreted from the schematics (of which I am not too keen at reading) I photographed my sketches and sent them to Jim. I told him I would not even heat up the soldering iron if the drawings I sent were not correct. Jim obliged and kindly made some notes and changes along the way.
After a few days I was certain how to re-build the power supply and attack the rest of the project. I was so cautious that I when I pulled the bracket, I dry fit all the connections and photographed them and sent them back for a check before I soldered the connections. I'm not an expert and I know a veteran could spot any minor-major mistakes.
In about a day or two I had a nice looking power supply, choke, and in-rush limiter all set on the bracket. I left it out of the amp while I tackled the next step, pulling out every resistor and cap, replacing them one by one over the course of 2-3 weeks. I tested the value and connection of each component before and after I solder them in. I replaced any suspect looking wires as well. I dropped in the power supply and created a clean grounding contact- pretty darn tricky in such a small space..The Citation V is compact, tricky and jammed with boards.
Jim suggested I add an important tool to my collection, I had been meaning to get a variac, as no good tube man should be without, so I ordered one, and while I waited for that to arrive I installed the meter kit..
Finally I got a quiet night and decided it was time for an initial power up. Now if some of you have read my posts before, you know I have a complex about turning on these units for the first time, so I was really happy to get the variac. Even so I was still antsy on power up. I plugged the unit in and slowly brought it up, waiting a minute or two before I moved up the voltage. I hit about 70 volts and I saw the output tubes start to glow. It was a great result, so I went the rest of the way right ?... ah no I decided to call it a successful night and shut it down. I wondered that if something were to go wrong, would it have occurred already? was I out of the woods? I wanted to ask Jim about it, but unfortunately he was out of town for awhile on business. I decided to call in "The Wolf"- inmate Mike Samra..
Mikey, if I get up to 70 volts and nothing blows up, do you think I am safe? -simply" yes" you should be fine, power up the rest of the way! -so next night after his reply I powered it up the rest of the way and I just let it sit for awhile. Everything seemed OK all the tubes (new from Jim) were operating. I thought, great, another successful night. I'll let it warm up and do the DC and AC balance.... and sadly this is where the good fortune started to fade.. while trying to do the balance operations, I noticed the output tubes started to pulsate and oscillate. The output tube grids would pulse and oscillate when I tried to adjust the AC balance. This was not good......
I was able to get the DC balance and this stopped some of the oscillation, but the AC was being picky especially on one channel.
I thought I"d try to hook it up and see if I got any sound..... bad news, very distorted, what could I have done wrong? I shut down and called Samra the next night to consult. Mike gets really focused when there is problem. I don't know how he does it but he sits on the phone looking at the schematic and can instruct me wire by wire, connection by connection by simply looking at the schematic and referring to his past experience. We went over all the voltages on both the output and the input tubes. Everything seemed right on. We went over all the numbers till about 2:00 AM. Mind you, he is on Atlantic time and I am on Pacific time. So while it was 2:00 am for me it was 4:00 am for him.
The next session we got more into it trying to trace down the distortion. From what I described, Mikey felt the problem must be in the feedback loop so again under his supervision we went through all the circuits and measured the resistances. We even disconnected the feedback loop entirely to see if this cleared up the distortion...Mike talked me through everything, telling me what to unsolder and what to check step by step, tediously, He seemed to take over as if it was his very own amp. We didn't have any luck and I have to admit at this stage I was feeling pretty bad about it, but Mike was not the least bit phased by it. We'll try again tomorrow, he said..
The next night or two we focused on the AC balance, I persuaded Mikey to help me trace this down, maybe we could have some luck with solving this problem, and perhaps this would lead us to why we were getting the distortion. It was a this point that I began to notice that V4 on the side that would not balance, seemed unusually hot. I took a shot of it and sent it to Mikey for his opinion.
It was hard to say, so he recommended we do all the voltage checks on that socket. Under his guidance again, we went through the voltage checks. Everything was spot on until we hit pin 7... it registered "open" or O/L... "bingo!" Mike said, you must have a power supply problem somewhere but when we went back through it, there was no problem with the power supply.
Now I might be a newb, but I knew most likely what that meant I could see the power lead running right to the output transformer from that pin.....I said to Mikey, " it's the output transformer isn't it?" He was reluctant to say so and there was a thread of hope, that it wasn't the problem, but after he instructed me on testing the connections across the power leads, it was true..the output transformer was open somewhere, and once we reached that conclusion my heart sank. .. It was 3:00 in the morning and this was the 4th night in a row we'd been up trouble shooting this thing... I was beat, lets call it a night...
How could I be such a fool, I should have tested the transformers even before I bought the damned thing (remember that factoid I said to note..)... what a newb.. I took a rest the next night and thought about options for getting a transformer (highly unlikely) I informed Jim about the set back, and Mikey also checked out some options for a transformer.. Jim had the best option, a connection he had could get it re-wound. It was at this point I thought damn, didn't I say this was a doable project? I was going to re- do the whole amp and do a full restoration, but Geeez I didn't mean replacing transformers, it wasn't supposed to get this far out of control! What kind of project did I get myself into? I was way over my head now...but things were just only beginning...
The phone rings at midnight on a Thursday...What Mike? you want me to what? are you out of your F*$%ing mind? I never done this before -I can't believe you are going to convince me to do this.. Samra calls with what seemed to me to be a radical plan... based on a minute chance of something he ran into with a transformer problem in his adventures.. Mike seemed convinced that the short had to be "reachable" -that there was hardly no way that a short, deep inside the coil could occur because all the other voltages except one was off; that meant to him, the transformer was "mostly" good. I didn't have any faith in that idea at all to be honest, and just to be frank, the only reason I was going along with this plan was because I felt I owed it to him for caring as much about my now defunct project more than I did...Sure what the hell, the transformer was no good any way, what was there to lose?
At another 2:00 AM shut down on a Thursday night, yours truly, "newb vintage amp restorer in training" pulls off a hallowed Freed transformer and sets it on the bench. I am calling it night.. I do have a regular job at which I been showing up half asleep due to this little "side project" :) I had to recoup because what Mike is asking me to do the next night, is opening up that very transformer and doing some surgery. Yes that is right, yours truly, newb vintage amp restorer guy in training is now pulling apart a transformer, cutting and dissecting delicate protection paper and hair thin copper windings looking for who knows what? so much for my f*#%king probability subroutine for judging success, that grand evaluation was dead wrong on this project. Here I am looking for what Mikey?.. what the hell am I doing opening up things that only qualified sacred hallowed technicians, with years of experience are supposed to touch? this is nuts.. I am miles outside the target, what the hell kind of detour is this.......hold on a second, what's this?...
When things looked about as hopeless as it could, I discovered something when I peeled back the protective paper one of the output leads. In fact, it was the one we suspected was shorted.... I spotted a burn mark on the plates......
and what do you know, I detected a hair like copper strand that had been severed just inside the bell housing... Now where was the connection..What did I find?....again hope was lost, all that remained was maybe a 1/2 millimeter of braid just enough to feel with a probe, protruding from the core.
I pulled out my meter and sure enough that tiny nub was where the short occurred, now was there any way to fix this? I took some pictures and showed Mikey he was now convinced more than ever after I showed him the readings that it could be saved. Again I was doubtful, only a 1/2 millimeter of braid to re-connect to, but Mikey convinced me to forage ahead and felt I could re-solder it..
I set aside one night just to try and solder the connection back on the 1/2 mm nub, and we are talking a dog hair thickness here. I scraped away some wax and got maybe 1mm to play with. I made the tightest loop I could with the braid and I knew I'd have like one shot to get the iron in there and flow some solder.... Somehow, I got lucky on the first try and it held. A check with my meter showed me the connection was back!. Lets wait until tomorrow to put this back together...
So this is the part where I miraculously tell you that I got it all back together and it worked!!! I wish I could say that. I gave Samra another call and told him I'd have the transformer back in tonight and we'd run some tests again under Mikey's good graces, he said not a problem, call him as soon as I could, It was almost like he couldn't wait to hear the news. The Citation is a cramped little amp, and getting a transformer in and out is quite a chore, surgery in itself. Getting the screws lined up with the PS bracket in there is damned tricky and I could write another novel on just that method alone, but suffice to say it's a very difficult and trying task. It's about 1:00 AM and I am ready to power up. Mikey calls me up and says is it working? .......Sadly and I mean in defeat sadly.. the answer was..... no... that damned lead would not give the correct voltage...Damn!
Mike, however, was not the least bit phased by it, undaunted, he is convinced it will work, even though we got the same result as before. He is certain that when I put the transformer back together that the leads touched something and grounded. Perhaps not enough protective paper was put back in the bell housing. Are you sure?-- yeah that's all it could be, he says according to the readings we get when going to ground you are grounded somewhere in the transformer, it's the only place it can be. Part of me is happy that he is so positive, yet part of me wants stab myself with the meter probe, like right in the gut. It's 3:00 AM and that goddamn transformer is coming out ...again....
I de-soldered all he connections again pulled the transformer, yanked off the bottom bell-housing and here I am again inside the transformer with that delicate solder joint just holding.. I taped all the connections and isolated them and added tape and paper to protect the leads against the bell- housing. I thought when I started this restoration I'd be replacing simple resistors and coupling caps just taking my time, methodically moving through each stage, nope, I am opening up transformers ... yep do it all the time now :)
Now this time, before I re-install the transformer, we are going to be smarter about this...Mikey calls me up and says we are going to do some tests on the transformer, power it up with your variac before we install it to make sure it works all re-assembled before you put it back in!. Using the variac, Mikey instructs me over the phone to hook up my meter to the speaker leads of the transformer, and slowly bring up the power on the variac till I get one volt. We used an extension cord as a receptacle for us to stuff the power leads in so the variac could connect power to the transformer.. When we reached one volt, we shutoff the variac down then inserted the meter in the variac itself and disconnected the transformer leads. We took that voltage reading and multiplied it my the OHM tap and we got an impedance figure for he transformer itself. It came out to spec exactly on every tap. Mikey was even more convinced it wold work this time once I reinstalled it, he thinks that I had fixed the problem..
Next, begins the 2-3hour process of hooking the transformer back up and mounting it again. I got the system down, but it takes just as much trickery and effort to install it as the first time. I solder up the connections.. it's after 2:00 in the morning again, for the N-th night in a row now, I lost track... I powered it up cautiously as ever on the variac. I took all the voltage readings including the pesky V4 tube, hey it came back correct! I warmed the amp up and got the DC and AC to balance, no oscillating! I plugged in the pre-amp and sent some signal through it.......wouldn't you know something..Mike Samra was right, the damned thing worked!
The Citation V is playing sweet music now, and I have to thank Mike who convinced me to stick with it even after I lost all hope in being able to get it back running. Mikey lights up when you got a problem, he's just as curious and determined to solve the issue as much as you are, like it's his own amp. All the consulting and countless hours past midnight, which are hours like 4-6 am for Mike, are all because he was driven to help me out. I can't say how much I appreciated him being so on target with this amp, without him and Jim's help, I would have been in serious trouble on this project. Mikey never asked for anything in return, he was just thrilled that he could help me out, they don't come much more helpful, than that, stand up guy, thanks Samra, I owe you big on this one..
Look for my review of this unit running in parallel with another restored McShaned Citation V and a head to head comparison of that set up with a restored Citation II :)
---the still wiped out, newb vintage amp restorer guy
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Topic - A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - mr9iron 02:11:57 02/16/12 (15)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - sj701 21:37:09 02/18/12 (0)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - DannyR 20:03:32 02/17/12 (3)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - mr9iron 10:24:41 02/18/12 (1)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - DannyR 12:40:53 02/18/12 (0)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - rmyauck 21:24:56 02/17/12 (0)
- Wow! What a place AA is! Kudos to you all. - notben 13:43:17 02/17/12 (1)
- RE: Wow! What a place AA is! Kudos to you all. - mehawt 18:20:56 02/17/12 (0)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - Michael Samra 18:02:51 02/16/12 (1)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - mr9iron 18:46:16 02/16/12 (0)
- If I was in a Fox hole, either- Mikey S. or Jim M. could watch my back- good job........nt - Neff 16:41:37 02/16/12 (0)
- RE: A Citation V Chronicle, Big thanks - Mikey S. and Jim M. - jarebjr 16:37:34 02/16/12 (0)
- Thank you for the Story and the affirmation of how KIND Michael Samra IS. ~nT - Cleantimestream 15:48:38 02/16/12 (0)
- Dang! good work! nt - Ralph 14:09:10 02/16/12 (0)
- Thanks for sharing such a great story, with awesome pics. Mike is a treasure and has been....... - viridian 13:47:22 02/16/12 (1)
- RE: Thanks for sharing such a great story, with awesome pics. Mike is a treasure and has been....... - mr9iron 14:48:59 02/16/12 (0)