ADA Depot - A Forum To Support Users of ADA Amplification Gear

Let's Get Technical => All PREAMP Tech Tips & Support => Topic started by: Richie_B on October 20, 2016, 02:38:21 AM

Title: Chorus issues.
Post by: Richie_B on October 20, 2016, 02:38:21 AM
Hey guys, Due to work I've been kept busy. Alrighty... a little while back I was having a few issues regarding drops in volume. I do think that's either the guitar lead or jack. The issue that is really bugging me is the chorus or lack there of.

I notice that on chorus patches it either sounds like it clips or there is no effect at all. An example would be 26 Sparkling Chorus where it just sounds completely clean. On 6 Clean with Compression is where it clips and distorts. There is no red light type clipping, it's just the wait it has been sounding.

I put new tubes in yesterday, the Mullard long plates which apart from what is going on right now sound good. Could it be the trimpot, I don't know. Hoping for a solution from the experts :)
Title: Re: Chorus issues.
Post by: Harley Hexxe on October 20, 2016, 04:41:37 AM
Hey Richie,

    Did you try plugging in your guitar cable into the other jack to see if it still drops the volume?

    I don't believe the Chorus issue is with the trimpot, it sounds more like an op-amp, but I'm only guessing at it. MJMP might have a better idea where the issue could be.

      Harley 8)
Title: Re: Chorus issues.
Post by: MarshallJMP on October 20, 2016, 05:03:10 AM
Hey Richie, can you send me a soundclip?
Title: Re: Chorus issues.
Post by: Richie_B on October 20, 2016, 03:27:56 PM
Hey Harley, The rear jack has never worked, I'll have a go at repairing it one day. MJMP, Ive attached a clip of the issue. Sorry about the quality, recorded it on my phone.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 21, 2016, 05:30:46 AM
The trimpot of the chorus bias should be set at around 11 o'clock, is that the case?
Title: Re: Chorus issues.
Post by: Richie_B on October 21, 2016, 06:14:43 AM
I just went and checked, I think I had set it before. It looks pretty close to 11 o'clock. Here's a pic just to be sure.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 21, 2016, 07:46:32 AM
try to turn it a few times and set it back to it's original setting. Just to make sure it's not a bad contact in the pot.
Title: Re: Chorus issues.
Post by: Richie_B on October 21, 2016, 01:38:41 PM
Ok, will give it a try now. Just to be sure, its the trim pot on the far right. What IDid notice while i was in there was that the trimpot on the top left was turned down, i havent touched it. Other pictures ive seen have it up a bit. Finally is it safe to adjust while the unit is on? Cheers.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 21, 2016, 01:40:47 PM
yes you can turn it with the unit on. Just be careful
Title: Re: Chorus issues.
Post by: Richie_B on October 21, 2016, 02:35:52 PM
I turned the pot a few times then reset it. Am still having the same issue. turning it to the right, turns the chorus off, to the left give more break up.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 22, 2016, 05:52:04 AM
So when turning it you hear a difference?
Title: Re: Chorus issues.
Post by: Richie_B on October 22, 2016, 02:29:10 PM
Yeah when i turn the trimpot to the right, the sound is clean. At around 1to 2 o'clock and onwards its a clean sound, no effect.
Title: Re: Chorus issues.
Post by: vansinn on October 23, 2016, 06:32:39 AM
The clip sounds to me like it's the active electronics, not a defect trimpot.
Richie's comments doesn't indicate scratching sounds produced by the trimmer itself, when changing it's viper position; but merely that the intensity of the cracking goes up in one direction, and goes down in the other direction.
Thus, I - cautiously - conclude it's likely the associated electronics being at fault.

@Richie: try spaying the opamp and bucket brigade delay chip, i.e., the near-by chips, with cold spray when you have signal on, and report if/how this changes the cracking.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 23, 2016, 10:50:41 AM
So if I understand correctly,after 2 o'clock the sound is clean but no chorus effect, lower the sound distorts and no effect?
Title: Re: Chorus issues.
Post by: Richie_B on October 23, 2016, 10:27:54 PM
There's an update. After again adjusting the trimpot I've found that between 10 o'clock and a fraction after 12 o'clock is where the noise happens. Anywhere from all the way to the left to just before 10 and anywhere from just after 12 to all the way right is clear but still no chorus affect. I'm pretty much flying blind here but want to understand what it is and how to fix it.
Title: Re: Chorus issues.
Post by: MarshallJMP on October 24, 2016, 05:50:00 AM
So the problem comes when it's biased correctly.Problem is could be a lot of things. Do you own a second MP-1? this way you could try to swap some parts.
Title: Re: Chorus issues.
Post by: Richie_B on October 25, 2016, 02:26:30 AM
Unfortunately no, it took a long time to get this one locally. The only ones I've seen for sale are US voltage on ebay. As you may be aware, I would need a step down transformer to use one of those here. Also the price for purchase and then shipping, just for parts would be a bit high.
Title: Re: Chorus issues.
Post by: rnolan on October 25, 2016, 03:26:13 AM
Hey Richie_B, don't be afraid to grab a US MP1, an almost must do mod (IMO) is an MDRT and they run on both US and proper electricity.  Shipping is a bitch though  :facepalm:
Title: Re: Chorus issues.
Post by: MarshallJMP on October 25, 2016, 04:20:58 AM
Problem is that I can't like pinpoint the exact problem.
Title: Re: Chorus issues.
Post by: Richie_B on October 25, 2016, 05:15:38 AM
I've been having a good listen to the noise and can sort of hear the chorus. Its like you can hear the rate change if its adjusted but its like the noise itself is being chorused, if that's even a word. Not sure of the best way to really describe it, overloaded signal maybe. I need to check this again tomorrow but I think that even winding back gain settings tamed down the noise but again, the signal would go clean, like with the trimpot adjustment. I'll need to listen again with a clear head and ears.
Title: Re: Chorus issues.
Post by: Richie_B on November 02, 2016, 04:21:37 AM
So far all I've been able to come up with is that maybe the signal into the chorus is being overloaded, causing it to clip. Ive been looking around for examples of this happening in regular chorus pedals. There's been a word here and there in forumsbut nothing to any great detail.

Not sure where to go from here, It's driving me crazy.
Title: Re: Chorus issues.
Post by: MarshallJMP on November 02, 2016, 05:33:55 AM
Do you know anyone that owns a scope? If you do maybe we could do a skype session and I could help to pinpoint the problem?
Title: Re: Chorus issues.
Post by: Richie_B on November 02, 2016, 04:34:02 PM
I'll ask around as well as see if i can pick one up for a reasonable price.
Title: Re: Chorus issues.
Post by: MarshallJMP on November 03, 2016, 05:15:42 AM
Ok let me know if you can find one, I did this before and mostly with succes. You also need a function generator or something that can output a sine wave like a computers sound card.
Title: Re: Chorus issues.
Post by: Richie_B on November 04, 2016, 12:58:32 PM
So far no luck with the scope. I'm even looking to rent one but that is still kind of expensive. Some places were charging as much az it would be to buy one.
Title: Re: Chorus issues.
Post by: MarshallJMP on November 04, 2016, 01:01:12 PM
And a second hand one? Here you can find them very cheap on second hand sites.
Title: Re: Chorus issues.
Post by: Richie_B on November 04, 2016, 01:07:22 PM
I'll keep looking. Most things are more expensive here than elsewhere.
Title: Re: Chorus issues.
Post by: Richie_B on November 11, 2016, 07:00:08 PM
Still trying to track down a scope at a reasonable price. Just wondering what would be good enough, as far as specs go. I've seen a few digital ones out there, as well as these kind of cheap digital diy kits. The cheapest old school ones I've come across that have been for sale, the seller wont post
Title: Re: Chorus issues.
Post by: MarshallJMP on November 12, 2016, 10:40:07 AM
Well I see several old 80's scopes selling here for 25-50 euro.I guess everyone is ditching their old scopes here for digital ones.I keep my old scope although I got a brand new MSO digital scope last year.

Now I would stay away from these DIY kits,they are usually crap. And the digital ones are too pricey? If you need help with these let me know (you can always email me with questions about the models and prices)
Title: Re: Chorus issues.
Post by: Richie_B on December 04, 2016, 05:14:41 AM
Still no luck on the scope front. Nothing close by thats affordable, starting at around $200. I did see one for $75 but it was in another state and pickup only. It's frustrating.... will keep looking and asking around.
Title: Re: Chorus issues.
Post by: vansinn on December 04, 2016, 09:26:16 AM
You're located in the US where there's a lot of HAM stuff going on, so I'd suggest looking up the local HAM club, and see if they could help you with an affordable scope.
An older Tektronic 10 MHz dual channel or similar thingy is all you need..

I agree with MJMP on the cheap DIY kits - I looked into those too. The more expensive ones could be ok, but there's always the issue with how to calibrate them, as those most always displays data on a PC via USB, and as such.. how accurately do they render data on the screen.. :dunno:
Title: Re: Chorus issues.
Post by: Richie_B on December 04, 2016, 01:16:10 PM
Hi Van, I'm in Melbourne Australia. Not all that common  here, for a reasonable price anyway.
Title: Re: Chorus issues.
Post by: vansinn on December 05, 2016, 01:06:25 AM
Aw, sorry 'bout that mistake, mate; thought you were in the US..
Never take an Aussie for anything else, might risk getting shirt-fronted :nono:

Hehe, same thing with crazy Cannucks.
One night I heard noises from our motor cycle parking. A nice girl returning from party quite a Bit drunk had fallen in love with a Harley, and were sitting on it taking selfies.
I opened my window, we had a chat, and I asked which state are you from.
I'm Canadian, what the fck else would I be.. :lol:

Which of curse has nothing to do with chorus or scoping it out, but then again, there's so much weirdness going on here anyways, so.. :dunno:


EDIT: Just did a brief search on "melbourne home radio amateur HAM" - seemingly a fair amount of links; you just might get lucky..
Title: Re: Chorus issues.
Post by: Richie_B on December 05, 2016, 03:12:46 AM
Depending on the part of the world, we get mistaken for New Zealand or even UK.. I don't get it. :) Regarding the HAM links, definitely worth a look. Not having this noise sorted is getting beyond a joke, I've had to just walk away from it a few times. I've also been wondering what else it could be.
Title: Re: Chorus issues.
Post by: Richie_B on December 05, 2016, 04:35:54 AM
Ok so i asked locally in the musicians group regarding a scope, explained what it was for. They basically said dont touch it, leave it to a "good" tech to work on. Said I could end up with fried junk...  So that was pointless :)
Title: Re: Chorus issues.
Post by: vansinn on December 05, 2016, 05:07:17 AM
Yeah well, they may not be techies, and as such could be right - but you're surrounded by tech freaks in here, so.. ;)
Touching electronics with an isolated scope probe is rather limited in terms of potential damage.
Try the HAMsters and see what happens.
I would like to help out, but just too many things going on here..
Title: Re: Chorus issues.
Post by: rnolan on December 06, 2016, 02:16:15 AM
I picked up some things from my tech today, I asked to him to look out for a scope for you, I'll let you know if he turns something up.  I also talked to him about getting into ADA repairs so we can have someone local.
Title: Re: Chorus issues.
Post by: Harley Hexxe on December 06, 2016, 05:15:16 AM
I picked up some things from my tech today, I asked to him to look out for a scope for you, I'll let you know if he turns something up.  I also talked to him about getting into ADA repairs so we can have someone local.

Just hope he doesn't roll your ADA gear off the bench like he did your Marshall head, they won't hold up to that as well  :facepalm:
Title: Re: Chorus issues.
Post by: rnolan on December 06, 2016, 11:43:24 PM
Yeah that surprised me   :dunno: wtf, although I ended up with a new pair of EL34s for free.  He's a nice guy and seems quite good, he also works on keyboards etc so should also be good with the digital switching (that's the hope anyway).
Title: Re: Chorus issues.
Post by: Richie_B on December 07, 2016, 02:48:44 AM
Cheers mate, very much appreciated. I've been keeping an eye out everyday and still no luck. Once this one does get sorted, I'll look at tracking down another and do the 3.666 mod, but that's some time off.
Title: Re: Chorus issues.
Post by: rnolan on December 07, 2016, 04:00:56 AM
Bummer, well I spose there are techs and TECHs...  :facepalm: .  Allot of the bread and butter work is probably relatively straight forward  :dunno: .  When Pro Audio started importing ADA gear they had a really great tech (really nice guy and electrical genius..satellite engineer I think) I tried to chase him up quite a while ago, IIRC he'd passed away.
After lots of chats with the guy I'm using at the moment, I think he'll have a big learning curve to get his head around ADA preamps, but we'll see.  If I can get him keen (and that's my plan  >:D ), I thinks he's up to it. (hope springs eternal LoL).
Title: Re: Chorus issues.
Post by: Harley Hexxe on December 07, 2016, 06:18:11 AM
Richard,

    Even if he gets stuck with something, you could always refer him to our resident ADA Guru, MJMP :thumb-up: He can fix ANYTHING!
Title: Re: Chorus issues.
Post by: rnolan on December 08, 2016, 03:09:40 AM
Hey Harley, that's my plan  :thumb-up: .  Also all the mods have instructions etc so anyone in this part of the world who wants something done but isn't into doing it themselves could have him do it. Anyway see how it goes.
Title: Re: Chorus issues.
Post by: MarshallJMP on December 12, 2016, 05:24:07 AM
Maybe one of these may be interesting for you

http://www.owon.com.hk/products_info.asp?ParentID=79&SortID=81&ProID=175#sthash.HJBObrjN.dpbs

Title: Re: Chorus issues.
Post by: Richie_B on December 14, 2016, 12:17:04 AM
If you think it will do the job, I'll see if I can find one at a good price.
Title: Re: Chorus issues.
Post by: MarshallJMP on December 14, 2016, 02:22:59 AM
The only thing you need is laptop or a computer.They seem to be decent usb scopes, better then those handheld ones.
Title: Re: Chorus issues.
Post by: vansinn on December 14, 2016, 08:08:17 AM
Some use a cellphone with a tone generator app for troubleshooting; I guess some scope frontend kit exists to be used via USB and a ditto app..
I'd assume this might not exactly have the same accuracy as a real scope, but still be ample good enough for troubleshooting.

Kindof the useful approach to "more of a fluke than a Fluke" :lol:
Title: Re: Chorus issues.
Post by: rnolan on December 15, 2016, 02:18:17 AM
It looks pretty cool though  :thumb-up: .
Title: Re: Chorus issues.
Post by: Richie_B on December 28, 2016, 01:23:22 AM
I hope everyone had a good christmas. I was taking a look around today and came across this scope, wondering if it would do the job.

http://www.ebay.com.au/itm/Hantek-6022BE-PC-Based-USB-Digital-Storag-Oscilloscope-2-Channels-20MHz-48MSa-s-/201749392924?hash=item2ef9336e1c:g:eP4AAOSwHaBWjxtA

Title: Re: Chorus issues.
Post by: DannyjoeCarter on January 12, 2017, 01:08:40 AM
Hello Richie B!
 I was following this thread because my buddy's MP-1 had the chorus just stop working altogether two days ago after 30 years of use! He got his in August of 1987 and never had a problem with it - until Monday!  :facepalm: So I was just seeing what was happening with yours to hopefully get some info for him.
 I will check back  :)
Title: Re: Chorus issues.
Post by: MarshallJMP on January 12, 2017, 04:04:48 AM
Hey RB, seems I missed your response, but the that scope looks good for what you need it, sample rate is a bit low but for the rest it looks okay.

@Danny, di you go through this topic? did you try some of the things to try out?
Title: Re: Chorus issues.
Post by: DannyjoeCarter on January 14, 2017, 02:11:11 AM

@Danny, di you go through this topic? did you try some of the things to try out?

 No not yet, we just bought 4 more units Buddy. We are going to retire the 1.38 anyway so we won't really do much more with that one. The 2.00 and 2.01 version have the rear inputs plus the extra features I wanted so I'm letting that one a lone for the time being.
 :D
Title: Re: Chorus issues.
Post by: vansinn on January 14, 2017, 04:40:47 AM
OT: Geez, four more.. careful you don't end up like the guy on Youtube with six Lexicon MPX G2's hooked to a hex-output pickup, i.e. one MPX per string :bow: :crazy: :facepalm:
Title: Re: Chorus issues.
Post by: MarshallJMP on January 14, 2017, 08:46:21 AM
okay Danny, just let me know if I can be of any assistance.
Title: Re: Chorus issues.
Post by: DannyjoeCarter on January 16, 2017, 01:16:11 AM
OT: Geez, four more.. careful you don't end up like the guy on Youtube with six Lexicon MPX G2's hooked to a hex-output pickup, i.e. one MPX per string :bow: :crazy: :facepalm:

 Yeah I know I know  ;D - but seriously I only use one in my rack and the others are for back up, and parts!!  ;D

okay Danny, just let me know if I can be of any assistance.

 Yes thank you and just an update MJMP, my Buddy Jason's MP-1 is a 1.38 and not only sounds thin but this one is also the one that I mentioned in another thread that is really heavy in the mids ( very Rockman sounding ) and he now hates it now! I mentioned that it may be an opamp but one of the four more we ordered sounds great and that one will be his main unit now.
 
 So after we get one more in fair condition I will start using parts from other spare units and start with swapping out the correct opamp and go from there and will touch base before hand  :)
Title: Re: Chorus issues.
Post by: Richie_B on January 16, 2017, 02:41:09 AM
Hey guys, I still haven't bought the scope yet. I've still been trying to track down an old real one with not much luck. It's becoming a frustrating experience trying to find the right equipment before we even know what could be wrong with the chorus. At one time I was given a quote from a local tech just to look at it. The price was $110 an hour with a 45 minute minimum just to look at before even working on it and the cost of parts. They couldn't specify how long it would take to work on. I was weighing up the cost of buying equipment over letting someone else do the work.
Title: Re: Chorus issues.
Post by: rnolan on January 16, 2017, 04:34:17 AM
Hey Richie, it's a hard one, in the end it would possibly cost much the same to buy another MP-1 if you can source one. Wow I just quickly checked evilbay, crap the prices are out there to get it to Oz... (hey DjC, have you got any good ones (since you are acquiring so many) to send our way for a decent price?)  For less than that money you could ship it to MJMP to fix (which is a definite option BTW) hey if only he lived here (or you lived there LoL).

If you want I can get my tech guy to look at it, I want to get him going on ADA preamps.  Obviously he's not free, but he's also a muso and a friend and won't rip you off (a charged hour of his time is reasonably elastic).  He's done a bunch of (good) work for me lately and been very reasonable price-wise. Also MJMP (and I) can/will help narrow his focus, anyway is an option..
Title: Re: Chorus issues.
Post by: MarshallJMP on January 16, 2017, 08:30:22 AM
110$ an hour, really???? Wow, that's expensive.
Title: Re: Chorus issues.
Post by: vansinn on January 16, 2017, 10:24:09 AM
Aussie dollars, I assume, but still expensive - even with World-record-over-taxed Danish eyes.
Title: Re: Chorus issues.
Post by: Richie_B on January 16, 2017, 11:56:13 PM
Thanks for the support on this, it's nice to have some realistic options. The hourly rate did seem high to me and what i didn't mention was that the tech also said they hadn't see mp1 schematics in a while but could probably source them. So basically I would have been handing it over to people that could possibly flying blind and on top of that, no idea of the final cost.. this is just for the chorus.
Title: Re: Chorus issues.
Post by: rnolan on January 17, 2017, 04:31:17 AM
Well we/you can make sure he got the schematics, they are all here although, lots of prior experience (and knowing MP-1s backwards) gives a major head start and a big save on troubleshooting time (eg MJMP).  My guy here in Canberra hasn't seen them either so I want to bring him up to speed.  First step is I'll take over a working MP-1 and MP-2 and melt him  >:D (he has a JCM800). But this will take time.

So you can buy a cheap scope and then try to sus it out, a good option IMO if you like to get under the hood  :dunno: .  The other best alternative IMHO is to send it MJMP and also get anything else done to it it needs. Postage will probably be around $200 there and back ? maybe less (they aren't particularly heavy). Not to piss in his pocket too much LoL, but MJMP does great work  :thumb-up: (he revamped both my MB-1s  :whoohoo!: ) and his prices are very reasonable (and elastic).  Unfortunately, the main ADA aware tech in Oz (Sid Barret) has (IIRC passed away), he used to do all the work on them for Pro Audio (Oz distributor), back when I did the guitar repairs for them...
Title: Re: Chorus issues.
Post by: Richie_B on January 18, 2017, 01:16:44 AM
Alrighty.... this just popped up for auction and its local. Any thoughts?

http://www.ebay.com.au/itm/20-MHz-Dual-Trace-Oscilloscope-/142239309700?hash=item211e1f9f84:g:iSkAAOSwEzxYc2h7
Title: Re: Chorus issues.
Post by: Richie_B on January 19, 2017, 03:03:15 AM
I was doing a bit more testing earlier. On patch 6 Clean with Compression,it does the clipping sound when it's on it's default chorus depth of 0.1. If I set the depth to 0, the sound is clean and unaffected. The same result happens when I have the depth on 0.1 but lower the master gain from 9.5 to about 7. All up, what I've noticed is that either by turning the chorus depth off or lowering the master gain, the result is no clipping. This is on any patch where the chorus is active, even distorted tones.
Title: Re: Chorus issues.
Post by: MarshallJMP on January 19, 2017, 12:47:09 PM
Scope looks good to me, ideal for audio repairs.
Title: Re: Chorus issues.
Post by: rnolan on January 20, 2017, 03:29:08 AM
Hey Richie, the compressor can add some VERY loud transient peaks which tend to clip things. eg my clean MP-2 patch makes my studio monitors clip from time to time, particularly when I belt the guitar a bit. Your results are not surprising, 9.5 is a very high master vol, with high compression (ie anything more than say 1.5:1 or 2:1 I'd call HIGH compression) it will send very strong signals to the next stage (which I'd expect to clip).  Now not to say eg 15:1 compression isn't usable (for say some nice (gentle) finger picking), you have to adapt for it (gain wise) down stream. If you "belt" a chord with that setting, expect clipping (in the eq and/or chorus stage ?) and turn things down accordingly.
It really helps if you understand the signal flown through each device and what each bit does to it along the way (gain structure). The MP-2 manual has a great block/schematic of the flow through it, MJMP posted the flow through the MP-1 quite a while ago.. (would make a nice MP-2 manual look alike MP-1 diagram MJMP?? if you were up to drawing it??).

Title: Re: Chorus issues.
Post by: Richie_B on January 20, 2017, 01:23:03 PM
Hey Richard, 9.5 was the default master gain setting for that patch. I am just wondering now what this all means for the broken chorus effect. As I mentioned earlier, when it's turned down the signal is clear and still with no chorus effect. This is the same with no matter what patch I use where the chorus is enabled. Now I know what I am listening for, I can hear the issue on any patch where there's even slight chorus. What I would be interested in knowing is how the signal flow works, how this would effect the chorus. Is it a trimpot, a resistor or something else? It's all interesting but I can't wait until it's resolved and I can think about mods to make it even better. I've considered saving some bucks for a second one to use in the meantime but wow, the prices have gone a little ridiculous lately, and as we know on this side of the world, shipping is a real killer. Kind of strange really because I can buy some gear from a German music retailer for a flat rate postage fee of $72 aud or there abouts. Probably some kind of deal they have with there postal service.
Title: Re: Chorus issues.
Post by: MarshallJMP on January 20, 2017, 02:18:48 PM
Well for the chorus, the signal after the loop is split into 2 signals, one is going to the outputs and one to the chorus

Filter to compression (NE570 1st part) to BBD to filter to expander (NE570 2nd part) and is then is mixed with the original signal (U11)

BBD clock is generated by a CD4046 (U24 )used as a VCO and in turn this one gets a voltage from a CD4094 (U25) which acts as a R2R DAC.
Title: Re: Chorus issues.
Post by: Richie_B on January 20, 2017, 05:04:55 PM
Thanks MJMP, still scratching my head over this and wondering whats next. Is it possible that something has failed along that path to cause the problem and if so, how difficult would it be to replace parts? I really hope I am able to do this myself, that in itself would be very satisfying. I really appreciate the help and support I've gotten here. If only I could get a few more mp1s to experiment on.
Title: Re: Chorus issues.
Post by: MarshallJMP on January 21, 2017, 08:07:18 AM
I guess is something is wrong in the audio path. But you need a scope to figure out were it is.
Title: Re: Chorus issues.
Post by: Richie_B on January 21, 2017, 02:32:04 PM
The bidding on the scope is getting too high, so will still be looking for one.
Title: Re: Chorus issues.
Post by: MarshallJMP on January 22, 2017, 01:57:23 PM
Maybe you're better off with one of those usb scopes?

Once you have a scope we can do a skype session and I can help you out.
Title: Re: Chorus issues.
Post by: Richie_B on February 01, 2017, 03:19:22 PM
Will go the usb option
Title: Re: Chorus issues.
Post by: MarshallJMP on February 02, 2017, 09:17:07 AM
Ok let me know when you have it.
Title: Re: Chorus issues.
Post by: rnolan on February 07, 2017, 10:12:05 PM
Hey Richie_B, I saw this today http://www.banggood.com/Orignal-JYE-Tech-DS0150-15001K-DSO-SHELL-DIY-Digital-Oscilloscope-Kit-With-Housing-p-1093865.html?utm_source=google&utm_medium=cpc&utm_campaign=Celc-DIY-ad-TIK-DSO150&utm_content=gary&utm_design=27&gclid=CP-57OO2_9ECFU1wvAodOYELiw  :dunno:
Title: Re: Chorus issues.
Post by: Richie_B on February 08, 2017, 12:18:27 AM
I wonder how well it works. I'm also wondering what the minimum sample rate should be, most of these that I've seen are 48MSa/s. I would hate to get one of these then realise that it wont cut it.
Title: Re: Chorus issues.
Post by: rnolan on February 08, 2017, 04:25:03 AM
MJMP will (no doubt) be able to check its specs and let you know, I just tripped over it today and saw it's really cheap and will hopefully do what you need to trouble shoot the chorus issue. Although I note it requires some SMB soldering (surface mounted), from the you tubes I've watched re SMB you just need the right tip for your iron.. and you flux the board connectors prior to soldering (not that I've done any SMB soldering yet..).
Title: Re: Chorus issues.
Post by: MarshallJMP on February 08, 2017, 07:58:10 AM
I wouldn't buy those banggood scopes, yes they are cheap but quality isn't that good.
Title: Re: Chorus issues.
Post by: rnolan on February 09, 2017, 01:33:43 AM
But would it suffice to do a one off job (ie this job ?) and help get his chorus sorted ??
Title: Re: Chorus issues.
Post by: MarshallJMP on February 09, 2017, 08:31:39 AM
Let's say it's better then nothing.
Title: Re: Chorus issues.
Post by: DannyjoeCarter on February 11, 2017, 01:26:54 AM
Guys I'm following this thread closely because I have two MP-1 with dead choruses. Is there an actual chip ( IC ) that controls the chorus or is there a series of things? I'm hoping I can just swap out a chip with all the units my buddy and I have -
Title: Re: Chorus issues.
Post by: MarshallJMP on February 13, 2017, 03:23:14 AM
There is a series of things.
Title: Re: Chorus issues.
Post by: DannyjoeCarter on February 13, 2017, 10:55:39 AM
There is a series of things.

OK I don't remember if the unit I sent you has chorus issues but if it does have a look Sir  :)
Two of the units we have sound great but have dead chorus's and when you have time I will send to you  :)
Title: Re: Chorus issues.
Post by: MarshallJMP on February 13, 2017, 02:01:13 PM
Well I just worked on your MP-1 ,it also had a dead chorus, but it was because the chorus bias pot was turned all the way down, returned it to the 11 o clock position and it works again (fine tuned it to the ADA specs).So check the bias pots on those units.
Title: Re: Chorus issues.
Post by: DannyjoeCarter on February 13, 2017, 02:31:37 PM
Well I just worked on your MP-1 ,it also had a dead chorus, but it was because the chorus bias pot was turned all the way down, returned it to the 11 o clock position and it works again (fine tuned it to the ADA specs).So check the bias pots on those units.

 Outstanding Sir!!!!!   :banana:
Title: Re: Chorus issues.
Post by: Richie_B on February 15, 2017, 03:09:16 AM
I wish mine was just a bias pot issue. I tried again giving it another turn back and forth to see if it would help and no go. Still looking for an affordable scope... which is still proving to be a very frustrating exercise.
Title: Re: Chorus issues.
Post by: Richie_B on March 22, 2017, 03:13:27 AM
This could be the one.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=112342193245
Title: Re: Chorus issues.
Post by: MarshallJMP on March 22, 2017, 05:46:27 AM
More then good enough.
Title: Re: Chorus issues.
Post by: Richie_B on April 28, 2017, 03:45:05 AM
I've been a bit busy of late and had to step back from sorting this issue. Regarding the scope, out bit on that one. I may be able to get a hold of another mp1 next week. I think it's an earlier version. My first question was, does the chorus work :) which it does. I'll keep you posted. Will still keep looking for a scope too. It's just that after a while all the searching gets old.
Title: Re: Chorus issues.
Post by: Richie_B on July 22, 2017, 01:38:22 AM
Hi guys, the saga continues but still haven't given up, well not completely. I've uploaded a video of the chorus/trim pot issue or what ever else it could be. It's me adjusting the trim pot to demo what I'm hearing.

https://www.youtube.com/watch?v=QUTN_Y_uRp8