Crate Vintage Amplifier Repair: Re-cap, Re-Tube, Re-surrection! (AmpMechanic  

Hi @Digital Chris... wow! this comment really made my day. Thank you so much and glad that this video could be of some help to you! Good luck with that amp!

@@AmpMechanic Howdy. Where can I find that circuit diagram with specs?

Just bought a club 50 myself. 2x12 version.. 1st, why is it called a club 50, when it's a 200 W system?? Mine doesn't seem to be getting any power. Honestly think the repair is over my head unfortunately. Never messed With any tube power equipment. Wish u lived close. Where are you located by the way?

@@incredifunk it's 50w! If you don't know the basics of electronic kit repair, do NOT mess with valve stuff - there are fatal voltages in there!

So the fix was essentially one cap and 1 tube?

Wow. Great story and thanks for subscribing. Sorry I didn't respond on a more timely basis. I love being closer to the analog world and knowing what's really happening behind all that digital stuff. Always good to bump into a bird of the same feather!

Welcome to the club! I've got a bunch more videos coming. I've been busy using the summer to get some outside work done while the weather is good. But I'm about to head back into the lab and have several videos part way through production. Stay tuned!

Thank you very much for the compliment. You can be assured that some of those mistakes won't get repeated as I refine my skills and my checklist.

Thank you @FWR! Production has been slowed down by my efforts to upgrade my video and audio capabilities. I have a new camera that I'm working with. So, more videos will be coming this year! Appreciate the great compliment!

Great to hear another one is joining the ranks. Keep us posted on how it goes!

Vlad, thank you so much for the great compliment. I hope it helps your amp tech. I have not touched the 50W version myself. These are some rocking amps. But the physical design?!!!! OMG. What were they thinking?

Andrew.. really glad you found this to be useful. I have more videos coming... took a break over the summer because I'm building a table with my spare time and needed the outdoor weather for all the cutting, sanding, etc. But once I'm back indoors, I will be back in the lab! Thanks again for your compliment. Compliments like these make me want to do more!

Same

David V thanks so much for the kind words. Made my day! Good luck with your amp.

Glad it could be of help!

@@AmpMechanic Hi. Nice video. I got one of these VC30's off ebay around 2004 or so. I was wondering if you think its possible to install a little fan inside the cabinet to help with the heat. Maybe even with its own toggle switch to turn it on/off manually. A fan like this one possibly? www.amazon.com/Ebmpapst-612NGHH-12VDC-0-25A-606025mm/dp/B07PR9G9JJ/ref=sr_1_106_sspa?dchild=1&keywords=mini+electronics+fan&qid=1603853835&sr=8-106-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzTjlJREVGOEc3SlpSJmVuY3J5cHRlZElkPUEwMjY2MTA5MkxQME9aMEtQMFQ0VSZlbmNyeXB0ZWRBZElkPUEwMjYyNDQ4M0pBVUZaUzhDS0g1TiZ3aWRnZXROYW1lPXNwX2J0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Thank you for the very kind compliment!

You're very welcome Thom!

I'll be the heads are great! This one was a combo of course (a big cabinet to hold all kinds of heat)!

I think it was late 90’s like 97ish

Thank you so much for the great compliment. LOL on bringing home the old gear. Sounds exactly like what happens to me. Sometimes, these sellers just want to unload everything and there may be just one item you want but the seller makes you take all of it for one price. I have literally cut off all purchasing until I get through all the stuff I've collected and restore and/or sell it.

@@AmpMechanicVintage test gear acquisition can get addicting fast! But what an awesome way to learn about electronics. I mentioned the Eico 147A Signal tracer. The magic eye has addled my brain. What a cool little guitar amp it would make with a 4" 30 watt Eminence speaker and some slight circuit mods to bring up the output from 3 watts to 12 ~ 15 watts. Anyway check out magiceyetubes .com. Also, what is blog/forum for Tektronix scopes you mentioned in your video that helped you with your groovy optocoupler tester? Thanks!

I like doing everything vintage. I wanted a fan like that for blowing off solder smoke. It's overkill. The thing creates a hurricane.

Sorry about that! About to publish one and have another in the works. Thanks for pushing me!!!

AmpMechanic I'm not pushing you because I'm a kind hearted do gooder. I'm a selfish arsehole that is jonesing for your next vid. That's how good they are. Get to tubin! BTW, I have been jamming through the Eico 147A Signal Tracer for a while now and it's awesome. Changed the original 1.5 watt speaker to a 4" 30 watt Eminence. But let not your heart be troubled... no vintage gear were injured during this film.

Thanks for the compliment. I've been working on a better video setup (building) my own light panels and such. That's why the delay. There'll be a video on that too.

Thanks Wade. Yes, I have a bunch of old tube radios here that are in need of TLC and I'll be turning my attention to them. Some have short wave like the Zenith Trans-Oceanic. I had an entire ham shack here at one point (it was given to me) and I was going to get that all up and running. But erecting a antennae was going to be a challenge and Covid hit and all and they stopped the in-person license tests. So, I paid it forward and gave the gift to someone else who could benefit from it immediately. I might circle back at some point.

Thanks for the great compliment. Much appreciated and great point on the mismatch on aging tubes (although I think it's good to have the originally matched spares if you need them in a pinch).

Fair criticism. Always looking to improve. When I did this video, the Bias Master didn't exist.

I don't think it matters whether you do it in Google Spreadsheets or Excel. The spreadsheet functionality that I rely on is not very sophisticated (something any spreadsheet technology can handle). Hope that answers your question.

Hi John-Jacob... all I did was an image search on Google for the schematics (there are two pages). The actual model of the Vintage Club 30 is the VC-3112. So, you may have to search that. I just tried it and found this link which contains the two schematics; www.4tubes.com/SCHEMATICS/Music-amps/Crate/?C=N;O=D

Volume cutting out can be an entire range of things. I'm guessing the issue is unpredictably intermittent or you wouldn't be asking since you'd have a better idea of the source of the problem if it was easily reproducible. If you don't have a lab full of diagnostic gear, you could start with a chopstick while feeding a signal into the amp with a poor man's signal generator (it's hard to feed a constant signal into the amp with your guitar while trying to do this) and then tap on components. For example, if you tap on the tubes, you might discover that you are able to toggle the issue on and off and then that could mean it's a tube or tube socket. Or, just pull the tubes, clean their pins with an emery cloth and clean the sockets with de-ox and see if that makes the problem go away. Also clean your jacks and pots. If that doesn't solve the problem, my focus would shift to some tests that may require a variety of test gear (signal tracer, oscilloscope, or a DMM that can measure in Hz), but the general idea is to start at the input with a signal generator feeding a 1 kHz signal into the amp and working your way through the signal path all the way to the speaker until you find a location where your measurement instrument starts to register the problem. If it's cutting out completely when it cuts out, you'll see a complete loss of the audio signal (Hz and AC will drop to zero). If the volume is diminishing significantly but you can still hear it, then your Hz might still be there but your amplitude (ac voltage) will show major fluctuations. A few things about the Vintage Club 30. The tubes are nearly impossible to get to when the chassis is in the amp. I have no idea what they were thinking when they did that. So, first, not easy to maintain. You basically have to pull the chassis to work on this amp. Second, when the tubes are way back in there like that with limited access to fresh air, it gets very hot in there (even with the ventilation they put into the amp). Second, Crate pushes the output tubes hard and runs these amps very hot. More than necessary as this is a Class AB amp. The tubes could easily be biased to idle. They're not. This exacerbates the aforementioned heat problem. Third, that amp runs on a printed circuit board and guess what HATES a lot of heat? Printed circuit boards. If you get a lot of intense heating and cooling, it stresses the solder joints on the board which in turn could cause them to crack. A cracked solder joint somewhere in the signal path could easily be the cause of this problem. As it swells and contracts in response to the heating and cooling, the signal may or may not be able to bridge the crack and voila, you have an intermittent problem like the one you describe.Good luck!

I apologize for taking so long to reply to this. Somehow missed it in my inbox. Volume cutting in or out can be so many things, it's hard to know. Since this amp is part solid-state (with a circuit board) and it runs extremely hot, one area of concern has to do with all the solder joints on that circuit board. The constant swings between very hot and cool (when it's off) can stress all the soldering and cause some to crack. Volume cutting in and out can sometimes be related to a cracked solder joint that is making a connection at one moment, but not at another. But the problem you describe can be related to SO many other things, so it's hard to say for sure.

Disclaimer: DONT try this if you have not understood the precautions in this video, and know how to drain capacitors. Even an unplugged amp can give you a fatal shock. Re-flow the solder on the foot switch pins on the circuit board. PITA to get it out. Don’t heat too hot nor too long. Use good solder and a magnifier.

Amen Ton7Tube. One cannot stress the precautions enough.

Stanley, this could be any number of issues that would be very difficult to diagnose without putting my hands on the actual amp (or "hand" because you never put two hands in there!).

The easiest way, if you ask me, is to start with the input jack, "listen" for signal, and work your way through the circuit until you have signal loss. Sooner or later, you'll encounter the bad components.

Sounds like great advice. I really appreciate your feedback. Thanks@@DavidBerlind

On that g40c XL I would absolutely start by either cleaning or replacing your instrument inputs. The originals are very cheap and I had the same kind of issue from mine from them

@@incredifunk I will certainly give that a try. Much appreciated.

Hey Doug.... though I don't know for sure, I suspect that the head won't have the sort of heat issues that the combo amp does. It's really hard to know without seeing the amp... but my gut tells me that if it started cutting out intermittently and then cut out altogether, that it might have been gradual progression of something like a capacitor going from bad to worse to just passing all DC. It's really hard to tell. I'm sure the VC 50 sounds amazing when its working properly. The best tool (and one that you can make pretty cheaply) is a signal tracer. A signal tracer makes it possible for you to check each step along the signal path to see where things go downhill. But if you're not sure what you're doing, then it might be best to take it to a tech. There's a lot of high voltage in that amp and one mistake could cost you or your Dad as much as your life. So please be careful. Let me know how it turns out.

@@AmpMechanic Thanks for the response and the advice! I think my dad and I will do a limited look over of things and if it's nothing obvious or within our abilities I will then take it to a tech if I can find one. It seems to be a dying art, at least around here... back in the day it was a lot easier to find someone who could work on these things. I definitely appreciate the warning and will remind dad about the need for caution, especially because of the high voltages in these units. Gonna get him to check out your video as well, as you talked about some of that and I want to make sure it's front of mind. Thanks again for your response! I really appreciate it! I will let you know if we figure anything out on it, or if we turned it over to a tech!

@@dougfa3515 Let me know how it goes. Be sure to download the schematic before you start working on it and if possible, use a local print shop (like Kinkos or Staples) to print it out on 11x17 paper (so it is enlarged). It may be multiple pages. The Crate schematics are very good with what voltages and oscilloscope wave forms you should be observing at various test points throughout the circuit (keep in mind the schematic is showing peak-to-peek values and you'll need to convert them to RMS). But you'll need a signal generator putting out a 1kHz signal at 1 volt RMS (if I'm not mistaken). The schematic tells you. If you don't have a signal generator, you can probably get by with a smartphone or tablet. The wave forms are not so important. You'll need a good real RMS DMM too. Where are you located? Worse comes to worse, if you really get desperate, maybe you can send it here. But that would the very last option.. basically a Hail Mary.

@@AmpMechanic Great advice, man. I never thought about enlarging the schematics... I've been trying to find one that's legible. But the Kinko's thing is a good idea... I can tell you've done this a few times... LOL I'm just outside Richmond VA. You're in the Northeast, right? That could be an option... Dad and I will check out some basic things and then we'll see how that goes and figure out what the next step is if unsuccessful. Again, thanks for the advice!

@@dougfa3515 Boston.

Hi Daryl, did you buy matched tubes? I thought about modding the amp so that I could individually bias tubes. But then ditched the idea and left that one big ballast resistor in there. Would have been major surgery for limited gain over purchasing matching tubes.

AmpMechanic I’ve never had a fixed bias amp before so this is all new to me. Mine is making this hum. Not sure where it’s coming from but as it is now, it’s unrecordable. The large caps don’t seem to be bulging. New to this stuff and already scratching my head over it.

@@daryllamont9942 So, the tubes are matching or no? Matching doesn't mean same model. It means they were literally designated by the seller has have matching profiles (usually determined with a curve tracer).

AmpMechanic oh yes, sorry. Tubes are matching.

@@daryllamont9942 the caps do not need to be bulging for them to have gone bad. These amps run super hot (the designers push the tubes quite hard) and there the amp was not physically designed with tube ventilation in mind. So, over the years, all that heat can easily cause the dielectric to dry out thereby ruining the caps. You could test the caps in-circuit if you have an in-circuit cap tester and maybe identify which caps, if any, are bad. But with this amp, you still need to pull the circuit board to get to their leads (which you'd have to do anyway to desolder and replace them).

Hi Eirini, are you sure you got all the filter caps? There are so many in there. Have you tone-traced the circuit.. (checking the circuit for hum through each step)? What about any wires carrying AC? Are they twisted to cancel the noise?

You're very welcome @RockR1... thanks so much for the great compliment!