ADA Depot - A Forum To Support Users of ADA Amplification Gear
Let's Get Technical => Troubleshooting Problems => Topic started by: NeverAfter on April 22, 2016, 04:36:01 AM
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Yesterday I had our bands rehearsal space to myself so I took the opportunity to get to know my MP-2 a little more intimately (no, not what you think!).
I noticed something was just not sounding right on the high gain presets. When I turned of the noise gate I got this extreme hiss on voices 6 and up. tapping the front panel of my MP-2 gave a microphonic sound through the speakers. (I haven't been able to reproduce that at home so it could have been a ground loop. I had my fcb1010 connected to a different wall outlet instead of the furmann.). Today I went to investigate this issue further and noticed that the V1 tube and it's surrounding caps and circuitry were very microphonic when tapping them lightly. The golden cap next to the tube socket seems to be the most microphonic, about as bad or even worse then the tube itself. The V2 tube does not seem to have this issue. I tried replacing the V1 as well as the v2 (and ofcourse both) with several tubes but to no avail. Below is a youtube vid where you can here the hissing and The microphonic sound I get when tapping the V1 tube. The hiss is much worse in real then it sounds on the video, same goes for the microphonics. At band volume the hissing is like static noise from a loud tv. In the video it sounds like the V2 tube is somewhat microphonic as well but that is just the board resonating along and making the V1 sound out a little.
https://www.youtube.com/watch?v=93vTEYIvc-A (https://www.youtube.com/watch?v=93vTEYIvc-A)
I also noticed that one of the larger caps near the psu has started to 'bulge up' slightly so I guess that needs to be replaced as well. Maybe this is the culprit? I'm not an electronics expert but I can handle a soldering iron a little (I previously did a succesfull R611 and R913 fix as well as deep mod for my Mesa 20/20). I know what a resistor and a capacitator do but that's about it. ;D
(http://i328.photobucket.com/albums/l356/Martin_van_Aert/Cap%20MP2_zpsvy5i85qa.jpg)
So, does anyone have any suggestions as to how to fix this issue?
Thanks in advance!
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Start with checking the high voltage.There is a testpoint just above R913.(H.V.),should be 190V.
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Thank you for the reply MarshalJMP,
I have no idea where and how to measure (but willing to learn!). I do have a good digital multimeter. Could you please tell me where exactly I should measure?
(http://i328.photobucket.com/albums/l356/Martin_van_Aert/Guitars%20and%20Gear/6BDC426B-4C5C-48DB-A98D-9799F351DE9B_zps1g5s3eiv.jpg)
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I mean I see the H.V. testing point but how to measure there?
Do I put the red probe on the HV test point and the black one across the R913?
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Red on the testpoint and put the black one in one of the screwholes of the mp2 (ground)
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Hey Martin, so you've found the test point (HV). To measure, select DC volts on your multi meter (range needs to incorporate/handle ~190v). +ve probe on HV test point, -ve probe to chasis (case), I use an alligator clip -ve probe lead and connect it to the case. You then need to power up with tubes inserted etc and measure (careful :thumb-up: ). From my experience (and chats with MJMP) you want it 190v or a little less is ok.. When I tested mine after R913 swap out it was 187v, the noise problem comes when it goes above 190v (but my rudimentary understanding is that R913 is the fix for this, R611 fixes noise gate chatter). The rest of the MP2 noise mod replaces 21 caps (including the one that seems to be bulging). So check the MP2 noise mod instructions (in the vault). Ideally you should do the complete MP2 noise mod (MJMP can supply you with all the parts if you want/need). The big caps are a bit tricky to desolder, the rest are not so hard (is my understanding). Tomy has just done this mod and has some good tips.
Since you've done R913 (and if it measures <= 190v at test point), then seems to me you need to do all the caps (ie MP2 noise mod)
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At the HV testpoint I measure 196.3 Volts, so that would be too high.
I think doing the whole noise mod would be a good idea anyways. I don't have that much soldering/de-soldering experience but I learn quick and now how to work carefully. The 25W DIY market soldering iron would have to make place for a soldering station before I would even attempt to do the whole noise mod though. I did replace the 913 years ago and it got rid of some 50Hz hum. Maybe I should try to re-solder it with a soldering station. I don't know if a bad soldering job could be a contributing factor?
MarshallJMP, does your noise mod kit come with noob-proof instructions? ;D
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Yes 196.3v is too high, you need it 190 or a little less (seems around 187v is ok). Now (again my rudimentary understanding, MJMP correct me if I'm wrong), R913 is the component that affects this voltage ? So you may need to replace it again ? (you get one with the noise mod kit from MJMP BTW). I agree, doing the whole noise mod is a very good idea :thumb-up: . Getting a decent solder station is also a very good idea. (and a decent desolder station even better (but not as essential). A quick check though, reflow R913 (remelt the solder joins) and test again (I don't think it will fix it but easy to try). BTW a bad solder job can always be a contributing factor.
The noise mod instructions are here (http://adadepot.com/mods/MP-2-NoiseMod.pdf), have a read it's hard to make this "noob-proof" but MJMP (and I to the extent I can) will help you if you need.
Some advice, line up your ducks, learn all you can/need before you start. Tomy has just done this mod, he can also help and has some good ideas to make it easier,
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Good to hear the R913 is included in the noise mod kit. I won't try to resolder the R913 right now because I don't want to risk damaging anything with my cheap soldering iron. It was a hell of a task swappping out the R913 and R611 with this thing in the first place.
Since budget is a little tight I would have to go for a cheap soldering station. Any advice on whether or not to go for a cheap one? They sell these starter kits which include a desoldering pump and some clamps with a magnifying glass. I would only use it occasionally atm. Or maybe it's better to see if I can lend a good station for a weekend.
I was looking at this one: https://www.conrad.nl/nl/basetech-zd-99-soldeerstation-set-analoog-48-w-150-tot-450-c-47849.html (https://www.conrad.nl/nl/basetech-zd-99-soldeerstation-set-analoog-48-w-150-tot-450-c-47849.html)
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Hey Martin, that station would be ok (good accessories BTW) but you can't set the temp as accurately as you can with the next level up. http://www.radioparts.com.au/product/38571665/zd929c-48w-soldering-station-digital-display-doss#.VxsdjXpPw0g is the one I have, it's worth spending a little more IMO so you can dial in the temp accurately. I was looking at one much the same as the one you are looking at, but they also had the better more expensive one that I bought and I'm glad I did. So from a quick search, seems the better ones will be around 69 Euros ($100 AUD).
When you did R913 and 611 did you do it from the top (like the American guy on the R913 youtube video), which is the wrong way to do it, or from underneath ? BTW when I did R913 I managed to wreck a pad :facepalm: so I understand your trepidation/caution.
Given you are close to MJMP maybe get him to do the noise mod for you ? Also if that's not the total fix required he can sort it for you ?
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[Smartass-mode on]If you buy cheap, you buy twice[Smartass-mode off]
At least in terms of tools and workshop equipment I learned that the hard way.
Check this station out:
http://www.reichelt.de/Diverse-Loetstationen/STATION-ZD-931/3/index.html?ACTION=3&GROUPID=555&ARTICLE=90918&SHOW=0&START=0&OFFSET=16&WKID=0&SID=12VxiwwKwQATQAAGwTNAg687bb40b7234e5b39569a4d8b6352116&LANGUAGE=EN (http://www.reichelt.de/Diverse-Loetstationen/STATION-ZD-931/3/index.html?ACTION=3&GROUPID=555&ARTICLE=90918&SHOW=0&START=0&OFFSET=16&WKID=0&SID=12VxiwwKwQATQAAGwTNAg687bb40b7234e5b39569a4d8b6352116&LANGUAGE=EN)
Just 15€ more than the one posted above but ways better and still *budget*....
BTW, thats the same one as this: https://www.conrad.nl/nl/velleman-vtssc40n-soldeerstation-digitaal-48-w-150-tot-450-c-77088.html (https://www.conrad.nl/nl/velleman-vtssc40n-soldeerstation-digitaal-48-w-150-tot-450-c-77088.html)
...just 30€ cheaper!
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NA will bring/ship his MP-2 to me and i'll replace the caps for him,seems safer.
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NA will bring/ship his MP-2 to me and i'll replace the caps for him,seems safer.
+1 :thumb-up:
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I'm taking my MP-2 to MarshallJMP tomorrow, it's less then a 1 1/2 hour drive. He offered to do the mod on the spot so I can take my MP2 back home with me (how cool of a guy is MarshallJMP!).
Of course I didn't (de)solder the R913 and 611 from the top, I know better then that! :) I have decided to save up for a better digital soldering station. I might even go for a Weller. I've been wanting to learn a bit more about electronics for a while and now seems like a good time to pick that up. I have some old pc mainboards I can practice my soldering skills on so I should be set! :)
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Hey Martin, well that's good to hear, when I saw that you tube clip I though what's he doing.. well he got it done but others will mimic him. The Wellers' are great (no doubt) but they are meant for all day every day and quite expensive. The one I bought has been very good (DCSS ZD-929C (https://zazz.com.au/daily/thingy/14716) it was about $70 AUD), I also bought a desolder station (Durotech TS-1513). These are both Chinese made and the same units are around with other branding/model nos. Good value for the amount that I use them.
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So NA and I had a nice afternoon while I did his MP-2.Talked a lot about gear and METAL!!! I also think I hooked him up to other ADA gear :lol:
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Yesterday I made the trip to MarshallJMP to get the noise mod done on my MP-2.
First off, it was great to meet MarshallJMP! He's an extremely nice guy and time flies when you get into conversation with him (I was too late for my band practise!). ;D
The noise mod has made quite a difference to the overal sound of my MP-2. The tone got a lot clearer and even a little brighter. I will test a little more in depth later.
MJMP also installed the 1.41 rom and I should have done this years ago. With fast preset change on I can hear no more dropouts between patch changes.
I also got an UNO chip for my FCB1010 from MJMP and have just installed it. Again totally worth it! The stompbox mode is just what I needed.
And ofcourse the mark of an ADAphile... my rack wears it with pride! ;)
(http://i328.photobucket.com/albums/l356/Martin_van_Aert/Guitars%20and%20Gear/76a61649-2af7-4293-a0de-c30b7382b2ee_zpsqjvnotrw.jpg)
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MJMP: I could have talked hours more with you! And yes you definitely did get me interested in some more ADA gear. You also saved me from wanting to buy an G Major. ;D
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Well just spreading the ADA disease :lol:
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:whoohoo!: