John Boner
Member
- Joined
- Aug 8, 2018
- Messages
- 30
- Reaction score
- 3
Hi all!
I'm not a compelete newbie to amps&electronics, but my understanding is quite limited. Though now I'm studying to be an electrician (my third vocation...) and I've started to fiddle more with electronics in general, and since I have a degree in music&technology, a better understanding of these things probably helps me along the way.
Anyway, to the subject at hand: I'm working on my '88 2210. The amp has a few issues which I've pretty much ignored for the 15+ years I've had it. The amp has had some work done to it, I followed the schemes today with the amp open. So, the reverb has been acting up every now and then. The amp sat around for quite a few years, I fired it up pretty recently and noticed that the issue has gotten way worse, the reverb sounds weak and when turned up over about 2 o'clock a pretty nasty brumm manifests, it gets a little quieter when dimed. Though I believe I found the reason for it, the pot measured little over 40k ohms on the worst spot and on full dropped some. It's a 100k pot and turns way too easy. I'll find out tomorrow. The 'verb not working properly hasn't bothered me since I really don't need it at all. With my previous heavy-rock band there was a few guitar parts where I would have used it at max but rarely even bothered to hook the footswitch.
Then there's the channel bleed issue which to my knowledge should have been fixed in a model this late. The normal ch bleeds to dirty, most noticeably on bass frequencies. I've checked a lot of posts on the issue, there are quite a few,can anyone point to the most obvious fix? Though I assume it has something to do with the fact that c38 is marked on the PCB, but the capacitor itself has been removed or maybe not even installed. Though I didn't yet remove the PCB and take a look underneath since the amp is in my school and I didn't want to leave it laying around with all the knobs etc out. I've checked the scheme and can't find it printed anywhere. Still I searched around and found pics with the cap in it's place. Also I don't know what kind of a capacitor it is. In the pics it looked exactly the same as many others nearby, I'll go with the same type if somebody can confirm me on that. The location is near the normal ch section. Would this fix the bleed issue? If I remember correctly, one of the suggested fixes was to check c40 and maybe replace with a bit bigger one. Other was about the IC operating voltage, swapping the two feeding diodes with schottky's. Any ideas on this issue would be extremely welcome. Someone suggested they might have accidentally marked c38 on the board but on the scheme it would be c40. This issue hasn't bothered me much either, I use the dirt ch for what it's meant, usually with a slight volume boost with a pedal, and the normal channel cranked for AC/DC etc tones. I've got another amp for clean(er) tones, and almost never have had any reason to switch the channels on gigs, I just kick the booster off and roll the guitar volume down. Cleans up enough for me, the gain on the amp isn't all the way cranked but the volume quite high (with a dummy load, of course, the amp is pretty damn loud. As a Marshall should be).
Then the last one, the amp sounds a bit muffled for a Marshall. I haven't had the chance to compare it with another 2210. I've taken care of that by using a Sonic Stomp on the fx loop with the "Process" dial turned up just a tad. The pedal apparently slightly delays bass/low mid frequencies which in a way reaches your ear a bit quicker due to longer wavelength. Or something like that. I'm not really looking for simply more treble/presence. The caps on the amp are most likely original, the filters are LCR brand. Yet still, the amp doesn't make a whole lot of noise, the normal channel keeps pretty quiet and the dirty (of course) hisses pretty much but nothing that I'd assume would have to with the filter caps. Now I really don't like to fix something that works, but the caps being as old as they are and when I take the PCB out and work on it anyway, would that "remove the blanket in front of the cab"? I like the idea of keeping it as original as possible but those electrolytes probably are about 30 years old...
This post came out pretty damn long with a quite a few issues, so if you made it this far, congratulations are in order!
All ideas welcome & thanks in advance!
P.S. I'm new here and I'm from Finland, I hope my "little novel" doesn't contain too many grammatical errors...
I'm not a compelete newbie to amps&electronics, but my understanding is quite limited. Though now I'm studying to be an electrician (my third vocation...) and I've started to fiddle more with electronics in general, and since I have a degree in music&technology, a better understanding of these things probably helps me along the way.
Anyway, to the subject at hand: I'm working on my '88 2210. The amp has a few issues which I've pretty much ignored for the 15+ years I've had it. The amp has had some work done to it, I followed the schemes today with the amp open. So, the reverb has been acting up every now and then. The amp sat around for quite a few years, I fired it up pretty recently and noticed that the issue has gotten way worse, the reverb sounds weak and when turned up over about 2 o'clock a pretty nasty brumm manifests, it gets a little quieter when dimed. Though I believe I found the reason for it, the pot measured little over 40k ohms on the worst spot and on full dropped some. It's a 100k pot and turns way too easy. I'll find out tomorrow. The 'verb not working properly hasn't bothered me since I really don't need it at all. With my previous heavy-rock band there was a few guitar parts where I would have used it at max but rarely even bothered to hook the footswitch.
Then there's the channel bleed issue which to my knowledge should have been fixed in a model this late. The normal ch bleeds to dirty, most noticeably on bass frequencies. I've checked a lot of posts on the issue, there are quite a few,can anyone point to the most obvious fix? Though I assume it has something to do with the fact that c38 is marked on the PCB, but the capacitor itself has been removed or maybe not even installed. Though I didn't yet remove the PCB and take a look underneath since the amp is in my school and I didn't want to leave it laying around with all the knobs etc out. I've checked the scheme and can't find it printed anywhere. Still I searched around and found pics with the cap in it's place. Also I don't know what kind of a capacitor it is. In the pics it looked exactly the same as many others nearby, I'll go with the same type if somebody can confirm me on that. The location is near the normal ch section. Would this fix the bleed issue? If I remember correctly, one of the suggested fixes was to check c40 and maybe replace with a bit bigger one. Other was about the IC operating voltage, swapping the two feeding diodes with schottky's. Any ideas on this issue would be extremely welcome. Someone suggested they might have accidentally marked c38 on the board but on the scheme it would be c40. This issue hasn't bothered me much either, I use the dirt ch for what it's meant, usually with a slight volume boost with a pedal, and the normal channel cranked for AC/DC etc tones. I've got another amp for clean(er) tones, and almost never have had any reason to switch the channels on gigs, I just kick the booster off and roll the guitar volume down. Cleans up enough for me, the gain on the amp isn't all the way cranked but the volume quite high (with a dummy load, of course, the amp is pretty damn loud. As a Marshall should be).
Then the last one, the amp sounds a bit muffled for a Marshall. I haven't had the chance to compare it with another 2210. I've taken care of that by using a Sonic Stomp on the fx loop with the "Process" dial turned up just a tad. The pedal apparently slightly delays bass/low mid frequencies which in a way reaches your ear a bit quicker due to longer wavelength. Or something like that. I'm not really looking for simply more treble/presence. The caps on the amp are most likely original, the filters are LCR brand. Yet still, the amp doesn't make a whole lot of noise, the normal channel keeps pretty quiet and the dirty (of course) hisses pretty much but nothing that I'd assume would have to with the filter caps. Now I really don't like to fix something that works, but the caps being as old as they are and when I take the PCB out and work on it anyway, would that "remove the blanket in front of the cab"? I like the idea of keeping it as original as possible but those electrolytes probably are about 30 years old...
This post came out pretty damn long with a quite a few issues, so if you made it this far, congratulations are in order!
All ideas welcome & thanks in advance!
P.S. I'm new here and I'm from Finland, I hope my "little novel" doesn't contain too many grammatical errors...