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

Let's Get Technical => Troubleshooting Problems => Topic started by: Chip Roberts on September 24, 2017, 01:51:10 PM

Title: No Power, No Display, No Output
Post by: Chip Roberts on September 24, 2017, 01:51:10 PM
Seems this problem has been reported on this forum before.  Went to power up the rack, everything turned on okay except for the MP1.  The OD1 light blinks once and then goes dead.  Pulled the fuse out and looks fine, doesn't look like the tubes are powering.  Please help.
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on September 24, 2017, 02:01:46 PM
UPDATE: Tubes are getting warm, so I know it's getting power.  Obviously plugged guitar straight in, not reading any signal.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on September 25, 2017, 02:37:10 AM
My stock unit does this, and yes the tubes light up and heat up despite nothing else appearing to be on.

Turn it off and on again in quick succession to see if it will fire up fully.  Sometimes mine will come on right away, but when it doesn't it's usually a case of flicking the on off switch a few times and then it power on properly.

Could be the issue, then again it may be something else.  But this works for my unit.
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on September 25, 2017, 07:06:00 AM
We measured the voltage on the 2200 capacitors and it didn't match up with that it's supposed to be (around 20-22vdc), so I'm banking on a relatively easy fix.  Any other thoughts aside from capacitors?  It's a version 2, production year is 1988 EPROM 2.01, serial number begins with 7.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on September 25, 2017, 12:55:37 PM
exactly,

so have you tried turning on and off the power switch a couple of times in quick succession?

My unit is getting power also when it does this, but comes on after the 2-3 flick of the switch.
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on September 25, 2017, 01:30:56 PM
Dad took it to the shop today.  Man says the amp is beyond repair, something wrong int he circuit board and claims there are no replacement parts.  When I get it back I'll try the off/on solution.  If not, I have another lead for a replacement.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on September 25, 2017, 03:19:51 PM
Well this can happen, now most tech guy are used to analog stuff and some freak out if they see all the digital stuff in a mp-1. Even if there is a digital problem all the parts are still available.
Now if it doesn't start it can be a lot of things, mostly the wall voltage being too low. So try if it wants to start without the tubes.

The voltage on the 2200 µF caps is not so important, the voltage over the 3300µF is, that's the voltage used by the 5V regulator that feeds all the digital stuff. The voltage over the 3300 is also used for the heaters, that's why you need to pull out the tubes to test it. Did you measure the voltage over the 3300?
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on September 25, 2017, 04:14:11 PM
The 3300 cap was normal, I'm in the US if that helps.  Amp repair diagnosis was; he was shocked that it ever worked based on the condition and that the volume pot was broken, he said that it had a lot of damage from someone dropping it, also said that he thought something in that board was fried and that all the IC's could be damaged as well.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on September 26, 2017, 12:35:26 AM
Holy smokes!  I guess your MP1 was in pretty bad shape then.

When you bought it Chip did you realise all that?


Sorry to hijack this thread - MJMP, in regards to my issue, would a simple replacement of the on/off switch do the trick?  I just have to flick it on and off 2-3 times for the unit to start.  Sometimes I don't have to.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on September 26, 2017, 06:11:40 AM
When you bought it, did it work?

Can you send me a couple of pics of the inside?

Did you try to start it without the tubes?

@RG, don't think the switch is the problem.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on September 26, 2017, 12:49:45 PM
MJMP, you don't think my issue is the switch then?  Once it switches on it's fine, works for as long as I want.  Perhaps a component has gone then, I dunno.  Mine has been like that since I got it.  Recorded on the album with it and everything.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on September 26, 2017, 01:43:16 PM
Could be the reset circuit, bad diode in the power supply, wall voltage a bit low,
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on September 26, 2017, 05:13:49 PM
It worked fine when I bought it.  Though shortly after the Output A on the back broke off and the rear input was all snafu.  Beyond those, never had any problem with it.  It's at my parents house right now, so when I get it back I'll try a few more things.  If not, I'll just buy another one, I got a couple leads.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on September 27, 2017, 02:10:51 AM
Okay, let me know how it goes.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on September 27, 2017, 02:24:30 AM
Could be the reset circuit, bad diode in the power supply, wall voltage a bit low,

Wall voltage low?  Wouldn't this affect my other MP1s?  Using a furman with this btw.

Shit, I dunno anything about the reset circuit.  Is that a serious issue do you think?
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 05, 2017, 07:11:56 AM
Hey MJMP, having observed my MP1 with the lid off, I can see that when I turn my unit on it definitely get's power to the tubes.  However no display or anything.  If I turn the swith on and off 2-3 times, then it comes on.  How do you think I find out what is causing the issue?
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 05, 2017, 02:02:21 PM
Does it start the first time if you get the tubes out?
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 07, 2017, 06:30:41 AM
OK tested with no tubes.

It didn't come on right away WITHOUT tubes.  Then I tested it a few times more.

It started to come on without tubes.

Then I put the tubes back in, it would NOT come back on with tubes first time round.

Then I took tubes out, it did come on first time.

Put tubes back in,  powered on, then suddenly it DID turn on first time round.

Mega confusing!!!

So it seems random, it will come on first time round sometimes without tubes and sometimes not.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 07, 2017, 08:53:08 AM
Is this unit stock or have you changed anything , like the noise mod?

Also can you take a pic of the upper right side (near the transformer/big caps) so I can see the values of the reset components?
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 08, 2017, 04:10:43 AM
Nope this unit is stock, stock, stock.

Not even the rear input mod

I'll take some pics for you  :thumb-up: of the area you mentined

My noise-modded/MDRT MP1 is rocking out fine  :)
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 09, 2017, 10:33:25 AM
some pics


ok had to remove links as photobucket apparently are being a bunch of fuckers and looks like my ten year relationship with them has come to an end.  I aint paying for shit to post my pics on the internet.

See attached photos
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 09, 2017, 12:31:25 PM
Can't see the pics? just something about updating your account?
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 09, 2017, 02:48:10 PM
updated my last post
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 09, 2017, 03:21:54 PM
Okay I see it has one of those crappy UK transformers, this could be the problem also.
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 10, 2017, 12:59:03 AM
Well thats the difference between the UK one and the US one?  Apart from the voltage of course?

Doesn't that transformer look stock to you?   (stock as in a UK voltage transformer put in by ADA)

So what can I do to test it?
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 10, 2017, 06:00:35 AM
Well the UK distributor bought ADA MP-1's without transformers in it and when they arrived in the UK they put in there own ones. But these are a lot smaller as the original ones. Later on they used bigger ones but I saw you have the small version. I replaced a few of these because they either failed on the high voltage winding or 9V winding.In the 1st pic the one on the left is an original transformer, in the middle an UK big one and on the left a small one like yours.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 10, 2017, 06:12:11 AM
So what you can do first is to replace 2 diodes (red arrow), the 3300µF/16V cap (red arrow) and the reset circuit (red block). If that still doesn't help you could put in a larger cap so the reset circuit keep the CPU a bit longer in reset mode.(yellow arrow).
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 10, 2017, 08:10:51 AM
Trust you to know all about it man!!!  Impressive as usual.

Ok I'll try get some of those components and swap them out.

On another note, is there a better transformer to get (besides the MDRT?)

I like the sound of this MP1 (its the one you said sounded "plexi-ish") so I'd be so I'm keen to keep it as close to possible.  I guess if I can get the crappy transformer to work better then I'd stick with it.  I mean really it's not a big problem right now (couple of flicks on and off with the switch) but if it has potential to worsen then might be better to replace it?
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on October 10, 2017, 02:03:24 PM
Well try out those things I said, if it helps ,fine if not I have a few 220V original transformers if needed. But try it out , could be a failed component but it could also be that the transformer is on it's way out. What ever it is I have your back  ;D
Title: Re: No Power, No Display, No Output
Post by: rabidgerry on October 11, 2017, 12:50:35 AM
Sounds good to me!

I'll track down the components I need and swap them out.

It's good to know you have my back  :thumb-up:  It's always appreciated.  That MP1 was a big part of the sound on our album so it's definitely a great one to keep living healthy!
Title: Re: No Power, No Display, No Output
Post by: rnolan on October 12, 2017, 02:26:41 AM
I just checked the (now spare) Australian transformer that Mike replaced with MDRT.  It looks like the one on the left with black tape.  I need to check my 240v MP1 that only worked for a little bit, as MJMP you said (back when I bought it) the problem may be power related.  The US MP1 I have works fine but (obviously) needs a step down transformer (which are heavy and a pain...)
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on December 13, 2017, 05:29:26 PM
Zombie thread:

After getting a new MP1 (which I love of course), I gave my old one to our other guitar player, as he's an electrical engineer and is interested in old tech like this.  He replaced one of the diodes and BOOM-it works.  Still needs some more work done, like replacing input jacks and volume pots, but now I have another MP1 for backup  :headbanger:
Title: Re: No Power, No Display, No Output
Post by: rnolan on December 14, 2017, 04:22:04 AM
Fantastic  :thumb-up: :whoohoo!:
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on December 15, 2017, 02:26:59 PM
Chip, could you ask him which diode was busted? it seems some of them start to fail
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on December 15, 2017, 05:17:51 PM
Not sure if this is helpful or not.  This was either the replacement or the original one before he pulled it out, but that's where it's located I guess  :dunno:
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on December 15, 2017, 05:19:29 PM
Here's another one of him testing it before the replacement with what looks like some sort of sonar device?
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on December 16, 2017, 03:43:35 AM
Did he replace the crystal? (the metal can like thing with the long legs)

Hmmm funny, never heard someone saying a sonar device to an oscilloscope  ;D
Title: Re: No Power, No Display, No Output
Post by: Chip Roberts on December 22, 2017, 08:51:16 AM
He did say something about having to order a diode with the correct crystal, yes.
Title: Re: No Power, No Display, No Output
Post by: MarshallJMP on December 23, 2017, 08:35:04 AM
Well it could be bad diode or a bad crystal or even both.