| Author | Message | |||
| bill90125
New Username: bill90125 Post Number: 1 Registered: 11-2004 |
I've used an F-1X faithfully for years and now there's an intermittent very loud popping that occurs. I know this preamp uses a tube. Is this a common symptom of the tube going out or something more serious? Thanks. | |||
| mica
Moderator Username: mica Post Number: 2137 Registered: 6-2000 |
Have a couple of questions to understand what's going on a little better. After the pop, does the signal return immediately or does it fade back in? Need to get an idea of the frequency of popping. Does it happen right away and then once every x minutes? Is it truly intermittent and has no predicatable pattern? What's the most number of pops you've experienced in a given playing period? The tube is easy to replace if it's needed, but I'm not entirely convinced that's the needed action in your case yet. | |||
| bill90125
New Username: bill90125 Post Number: 2 Registered: 11-2004 |
After the pop, which is quite loud, there is usually no signal, and then it will fade back in after a few seconds. The pops generally don't happen right away. Usually the unit has been on for a while. And I've had several instances where, with the preamp on but unused for some time, the pops get semi-rhythmic, and begin pulsing, although I don't think the time distance between them is consistent. I've had it pop just a couple times and go away, and then I've had it where it starts pulsing like I described. I have noticed, since the unit is loose in the rack at the moment, that if it starts the pulsing some movement of the unit sometimes stops it. Thanks. | |||
| alemboid
Intermediate Member Username: alemboid Post Number: 109 Registered: 5-2003 |
Any chance you are using a Stewart Amplifier with your F1-X? Alemboid | |||
| bill90125
New Username: bill90125 Post Number: 3 Registered: 11-2004 |
No, not using a Stewart amplifer. | |||
| mica
Moderator Username: mica Post Number: 2139 Registered: 6-2000 |
Another question for remote troubleshooting: does the popping sound happen every time after warm up, or does it happen that sometimes you can use it and have no popping? The fact that moving it sometimes stops the problem, it suggests a loose connection. I have some advice for checking for a loose connection, but first I'm going to take a picture to help illustrate the concepts. NOTE: there is dangerous high voltage in the F-1X. Do not attempt to troubleshoot if you do not have experience with electricity. Ponder my warning for a while then I'll take some pictures and post when I'm back from lunch. | |||
| fmm
Member Username: fmm Post Number: 53 Registered: 6-2002 |
What's the problem with using a Stewart amp? | |||
| alemboid
Intermediate Member Username: alemboid Post Number: 110 Registered: 5-2003 |
Nothing is wrong with using a Stewart amp as long as it is a 1.6 or a 2.1. I used to use a 1.2, and I used to get loud pops, loud enough where I thought I was going to blow a speaker. This happened regardless of volume, so I checked my F1-X through a different amp and it was ok. Eventually the Stewart pretty much blew up, so I called Stewart. They stated that the 1.2 isn't quite well enough equipped to handle a lot of low notes, especially if you are playing a low B. "The 1.6 and 2.1 operate much better for bass guitar applications. We don't recommend the 1.2 for bass" (yet, many stores will sell you one to use for bass). They were really cool about it. They repaired my amp, and I switched to a Mackie 1400 and never looked back. It was the eventual crapping out of the Stewart that manifested itself as several loud pops that I thought you may be experiencing- if you were using a Stewart 1.2....that's why I asked. Alemboid The Stewart sounded awesome, but I never knew it was a time bomb! | |||
| bill90125
New Username: bill90125 Post Number: 4 Registered: 11-2004 |
The popping does not happen everytime after a warm up. I may be able to use it one day without any popping at all. I do have electronics experience and a loose connection also seemed a possibility, but I wanted to check with you first to see if you've heard of this before. Any photographs or ideas on where to check would be appreciated. I have already popped the hood and checked for general tightness of connectors, but did this with power off. | |||
| mica
Moderator Username: mica Post Number: 2142 Registered: 6-2000 |
Here's the picture I took right after lunch:  It illustrates using something non conductive, like a Sharpie pen to lightly tap on the connectors while the F-1X is plugged in. You'll hear it if something is loose in one of the connectors. I also made a short movie of the tapping, to show only light tapping is required. Again, do be extremely careful if you have the F-1X powered and the cover off.
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| davehouck
Senior Member Username: davehouck Post Number: 1062 Registered: 5-2002 |
Cool movie!!! (I'm so easily entertained <g>) | |||
| bsee
Senior Member Username: bsee Post Number: 535 Registered: 3-2004 |
Bill- I think Mica's point about voltage includes with the power off. I don't know what's inside the F-1X, but capacitors can store power after they have been unplugged and let loose when touched. Power off and unplugged may not guarantee no electricity present. -Bob | |||
| bill90125
New Username: bill90125 Post Number: 5 Registered: 11-2004 |
I did as you recommended, tapping the connectors with the cover removed and the power on, and got no pops of any kind. I put it back together and used it for an hour and got a single pop out of it while using it. Just now it started popping and crackling continously. I bumped the case, and it stopped. | |||
| bill90125
New Username: bill90125 Post Number: 6 Registered: 11-2004 |
I'm guessing there aren't any more suggestions. How do I go about sending the unit in for service? Thanks. | |||
| stoney
Advanced Member Username: stoney Post Number: 340 Registered: 7-2002 |
I had the same EXACT problem with my (now returned) Stewart 1.2. stoney | |||
| son_of_magni
Intermediate Member Username: son_of_magni Post Number: 146 Registered: 1-2004 |
I notice in Mica's picture that there is a silver colored nut at the bottom of the circuit board most likely holding the board to the case. If there are any connections of this type that are used to make a ground connection to the case these are classic causes of the kind of intermittant problem you are having. I would carefully tighten any nuts of this type if it looks like there is an electrical connection. Again, be very careful not to touch the back of the circuit board or any components, even if the unit is unplugged, as capacitive discharge could damage you as well as the components. - SoM | |||
| mica
Moderator Username: mica Post Number: 2177 Registered: 6-2000 |
We don't do the grounding in the scheme described by SoM, but we've had a chance to talk and get you set up for the next test on your preamp. Tonight, try setting the volume at no more than 1 and see if you get the popping and report to us how loud it is. Depending on what you find, you may want to change the tube, though it's rare that a tube would cause the trouble you're observing. If we aren't able to diagnose the problem remotely, then we will make arrangements with you to send in the preamp. In this case you'd email help (at) alembic (dot) com and get the process going. | |||
| bill90125
New Username: bill90125 Post Number: 7 Registered: 11-2004 |
I turned it down to between 0 and 1. The popping still occurred and was still very loud. If you believe replacing the tube should be tried next, can you give me a reliable source and brand of tube that should be used, and basic instructions for replacing it (I do have electronics experience). Thanks for your help. | |||
| mica
Moderator Username: mica Post Number: 2180 Registered: 6-2000 |
If there was absolutely no difference in the popping sound then it's safe to say it's not the tube causing the problem. In this case, try replacing the 4558 opamp on the main preamp board. Let me know if you notice any change in popping sound after you replace the IC. Also, just for good measure, please plug and unplug a connector in the effects return jack about 20 times. It's probably not the cause of the sound you're noticing, but you mentioned you had used the F-1X for years, and this part will corrode if it isn't excercised. | |||
| bill90125
New Username: bill90125 Post Number: 8 Registered: 11-2004 |
I tried replacing the 4558, and also tried some contact cleaner on the jacks, without any success. Let me know if you more ideas or if I should send it to you for service. hanks. | |||
| bill90125
New Username: bill90125 Post Number: 9 Registered: 11-2004 |
Haven't gotten a response back. How would I go about sending this unit for service? Thanks. |
F-1X tap test