Crate Vintage Club 30 Problems

[cheezor]

I have a Vintage Club 30 that works fine for about 10 or 15 minutes (until it heats up) and then the volumes has large spikes intermittently.

I have tried all new tubes and I have also re-soldered every connection (I think lol) on the PCB. Same symptoms.

I think something is overheating, but I have no idea what. Any ideas before I take it to a repairman?

I would love to fix this great sounding amp!

[sumgai]

cheezy,

Here's a schematic of the pre-amp section for your amp:

www.blueguitar.org/new/schem/misc_amp/crate_vc3112pre.gif

(Not linked as an image, it's a bit large to show the detail.)

Yes, it's labeled as for a VC3112, but the pre-amp circuitry is the same for all the Vintage Club series - only the power amp and power supply sections change as power goes up or down.


The problem stems from the fact that the channels are attempting to either change, or to both come on at the same time. This plays havoc with the power supply, which you hear as a volume jump. So, here's what to check, in order:

1) The footswitch jack, for dirty contacts. The easiest way to do this is to insert a footswitch, and see what happens.

2) The panel switch itself. Is it dirty, loose and/or wobbly, sticky, etc.?

3) The opto-isolators. These are the the funny oval parts labeled as "opto" - there are 5 of them. Fortunately I have a link to another forum where this exact problem has been discussed, and the opto's are examined..... check it out:

www.thegearpage.net/board/showthread.php?t=162070

If none of that made any sense to you, report back here for a larger block of instruction.

HTH



sumgai

[cheezor]

Ok, first off, I think that I should tell you that Im not an electrician by any means. I know VERY little about electronics. I do know some of the basics. But unfortunately I dont read schematics very well. At first glance your post seemed somewhat Greek to me. lol

That being said I did locate the parts that you were talking about. (The opto-isolators).

The footswitch jack seems to be fine as well as the channel select switch (Im assuming that is what you meant by the panel switch). Everything seems to be pretty clean as far as the parts and connections are concerned.

So, now I was just wondering how to test those parts. I know that this happens on both channels, and Im assuming that if these guys are the culprits, then I have at least one bad one in each channel. Btw, the last owner said that it used to only have this problem on the clean channel.

I took a picture of the part and circled it just in case its useful in explaining anything.
img254.imageshack.us/img254/7222/copyofdscf0829jw8.jpg

Im contemplating just replacing all of them. (The brute force method. lol) Sounds like this might be a common problem and it might be a good idea to replace all of them while Im at it.

Thanks for all the info and help! You are totally amazing! I am leaving tomorrow on a trip and I wont be back for about a week so I wont get to try anything that you mention, but any feedback is greatly appriciated even if I dont respond for a week!

Thanks again!

[sumgai]

cheezor,

Yes, it is a common problem, so the "brute force" method (aka the "shotgun" method) is probably not a bad idea. If you can handle the de-soldering operations involved, then procuring the parts is the only thing left to do. Digikey might be a good place to start, but there are other parts houses out there.......

The fact that the problem is in only one channel or in both is not really helpful. The fact that the amp shows any problem at all is the whole issue, and these 5 components are the weak link not ordinarily seen in a standard amplifier design. I do note that OC4 is feeding OC2 and then OC1 in a serial fashion, ditto for OC5 feeding OC3. That's born out by the different resistor values for R9/R10. If I had to make a guess, I'd say that if either of these resistors is out of tolerance, then the current seen by the opto's is probably too high, and failure is imminent. I suggest that you replace those too, with 1% tolerance parts.

Awaiting your return to civilization.........



sumgai

[cheezor]

Hey, I got around the internet long enough to check back in.

I am pretty decent at soldering. I dont know what Im doing all the time(theory-wise), but I have done a lot of soldering so that wont be a problem.

As far as finding the part I think that I found a couple sources, but I haven't had a chance to look at digikey. I'll have to check that out. Tell me what you think of these:

www.smallbearelec.com/Detail.bok?no=347

cgi.ebay.com/Analog-Optoisolators-VTL5C3-Vactrol-4-PIN-2_W0QQitemZ170195878649QQihZ007QQcategoryZ50917QQcmdZViewItem?refid=store

This link shouldnt have a space in it, but for some reason it keeps putting it in there...

When I get home I'll have to test those resistors. Thanks for all the help!

[sumgai]

cheezy,

Either of those links goes to the correct part, so it's only a matter of whom you trust, and how much(little) you pay for the 5 units and shipping.

~!~!~!~

To make a long link work, check out the first post in this thread:
guitarnuts2.proboards45.com/index.cgi?board=reference&action=display&thread=1191120298


HTH





sumgai

[tacoman]

Did the new parts fix the problem? I'm haveing the same problem with my VC30..

[newey]

Tacoman-

Hello and Welcome!

Sorry that no one's gotten back to you on your thread on this problem. SG's the amp guru around here, and he's been away for a few days, but I suspect he'll get with you shortly.

Cheezor hasn't logged in for over a year, so we'll probably never know if this worked for him or not.

[tacoman]

Well thats cool,,i'm pretty paitent and really dont expect to get replies all the time..lol I've posted this problem on other forums no luck..

[newey]

TM-

Did you delete your original thread on this problem? While resurrecting this thread is fine, we'll try to get some answers right here, please don't delete threads just because no one's responded.

I was going to bump that thread but couldn't find it.

[sumgai]

tacoman,

Yes, as I answered above, the problem is well known by now (especially two years after this thread started....). While I've retired from fixing amps as a "hobby career" (after officially retiring from the real world), I still keep my fingers in the pot, so to speak, and constantly have feelers out for various "odd problems" like this. Not that it does me much good financially, but it's fun and a bit challenging to try and out-guess all those young whipper-snappers who think their Scheiße doesn't stink.

Follow the links above to procure the opto-isolators, install them (all of them, just to be sure), and your problems are 99% guaranteed to go away. (Why only 99%? Ever hear of Zeno's Paradox? )

HTH


sumgai

[tacoman]

thanks very much i will give it a try...And yes i did delete my post, I thought it may not be a good to have two threads with the same title..Sorry bout that

[sumgai]

t-man,

No problem!





sumgai

[daverules]

I AM SO FRUSTRATED!

Please tell me there is something else that could go wrong here.

I have the exact same problem:
Amp sounds AMAZING for 15-20 minutes, then starts to cut in and out (both channels.)

I called Crate to see if they are familiar with this problem, and the issues with the opto-isolaters. The technician wasn't familiar with the problem, and said that he hasn't hear of opto-isolaters going bad.

I replaced them anyway, but the problem is still there.

You mentioned that it the isolaters are in direct line with the power supply, and freaking it out....is it possible that the power supply could be going bad?

I've also switched the input and footswitch jacks, re-soldered the pots, tube connections, and any other loose one i could find.
WHAT ELSE COULD I BE.

The closest repair guy has a $60 bench fee, but I know I can do the work myself for free.

someone please help!!

[sumgai]

dr,

First, hi, and to the NutzHouse!


OK, here's how it plays out. Normally we techie types do one of two things - either we follow the rules and move in a linear fashion from one end of the amp to the other, or else we take a shortcut where experience tells us that we can save time. In the case of Crate amplifiers like yours, this means that we go for the jugular right away - the opto-isolators.

However, if they are not bad (as in, they've been replaced with known good parts), then we, acting as diagnosticians, have two choices - start troubleshooting in the time-honored manner, or take another shortcut. You've already done that, by "shotgunning" the obvious potential trouble spots like the jacks and various solder joints. OK, we'll stick with Plan A.

I'd start with the power supply. Heat related issues are more likely to crop up here. Fortunately, Crate provided some test points for us. Located on the board somewhere near OC4 is TP 10, and TP 11 should be near OC5. Check these points for both steady DC, and for any AC that might somehow be getting in there. If you find either glitchy DC or anything more than a couple of millivolts of AC at these points, your opto-isolators will play hob with your channels cutting in and out. At that point, you'll need to delve into the power supply itself.

If those two points work as they should, even after the amp is plenty warmed up, then something else is Ge-Fooey^© in there, and that's gonna take some first-class head scratching. I think I'd next check the 3.3v zener diode (D19) to make sure it's working. If you measure anything more than 3.3v here, replace it.

Let me know what you find.

HTH




sumgai

[myrios]

Glad to see there are other VC3112 owners out there working on this problem.

I picked one of these up at a garage sale for a mere $70, I'd plugged in a guitar, heard the initial awesome tone and there was no way I was going to pass it up.

However I'm having what may or may not be the typical problems: after being on for 10-20 minutes the sound starts to cut out, and there's some definite sort of white noise to it.

With my amp though, if I switch on and off the stand-by switch it can bring the volume right back to normal, but then it will typically cut out, so I'm praying that it just needs a good cleaning of the stand-by switch...

I'm hesitant to dive-in to this thing though... it gets time consuming and messy (must be getting old!)

Anyone have this similar noise and symptoms with the stand-by switch?

[tacoman]

Just an update.
I replaced all 5 opto-isolators in my Crate VC30 and it fixed my problem..They Where easy to replace, took longer to take the amp apart..lol

Thanks sumgai for the info and saving me a trip tp the repair shop!!many many thanks!

Greg

Feb 28, 2010 16:53:56 GMT -5 sumgai said:

tacoman,

Yes, as I answered above, the problem is well known by now (especially two years after this thread started....). While I've retired from fixing amps as a "hobby career" (after officially retiring from the real world), I still keep my fingers in the pot, so to speak, and constantly have feelers out for various "odd problems" like this. Not that it does me much good financially, but it's fun and a bit challenging to try and out-guess all those young whipper-snappers who think their Scheiße doesn't stink.

Follow the links above to procure the opto-isolators, install them (all of them, just to be sure), and your problems are 99% guaranteed to go away. (Why only 99%? Ever hear of Zeno's Paradox? )

HTH


sumgai

[sumgai]

t-man,

Glad it worked for you, and glad to be of some help! ;D

~!~!~!~!~
myrios,

As just noted, it's not that hard to replace these 5 components. Why not start there, and see if that doesn't cure your problem too?

And yes, monkeying with other parts of the circuit can seem to make everything work, perhaps only momentarily or perhaps for several moments, but if "fixes" like this aren't permanent, then I'd suspect those opto-isolaters first and foremost.

HTH



sumgai

[yostamplifier]

Okay, so i have been testing this amp like crazy. I think the optoisolators is a great easy target, but not necessarily the issue. After hours of deciphering the schematic of the preamp and the power supply, then trying to make sense out of the printed circuit board I think i may have discovered the problem. First, i did change all the opto's and still had the same problem, as well with tubes.
So, upon looking once again i noticed that this intermittent volume spike would come and go if i were to tap on any given spot on the pcb with an orange stick. how does heat then affect this issue? maybe heat is just a coincidence. What it boiled down to was the fact that somewhere was a bad/loose connection. I discovered the culprit.
IT'S THE EFFECTS LOOP JACK "tip contacts"!!! I stuck my orange stick in between the tip contacts to separate them from short and whammo there is the volume spike!!! The jack needs replacement or a simple tweek of the grounding/shorting tab (tweeked it up a notch to press hard into the other contact for the tip. So maybe heat can be relative: as expansion and contraction with hot and cold, these tips are fairly thin grade metal. it was so slight that it was real hard to find. Maybe one solve, if you dont use the effects jack, is to solder the "tip contacts" on the jack together to prevent them losing contact in the future (if you do dont stick a cable in it cause the contacts will then be closed down on eachother!)
Tested the amp and it works perfect. i will post back after a couple gigs to let you know the end result.
checkout my website yostamplifier.com (still under construction)

[newey]

Yost-

Hello and Welcome!

Please do post back, there seems to be quite a few enquiries about this particular amp.

Here's the link to your website:

Yost Amplifier