Mark III, Bad Soldering Point in a Series ???

[megavoice]

Hello may mates,

first of all I want to apologize to start a new thread as it`s related to my last one "Buzzing", but I think that it is too important for every Mark 3 owner and I want to attract more attention.

I pulled the chassis out of my second red last weekend for cleaning the power toggle switches and couldn`t believe my eyes again, A SECOND TIME:
One pin (most rear,left side) of the opto coupler right behind the "LEAD VOLUME" pot looks from above to be unsoldered with the printed circuit of the upper surface.
My first red fooled around from time to time for about twenty years `till I discovered that unsoldered pin accidently when controlling all the points in a routine with a mignifire.
I immediatly placed some solder tin from above and the amp is functioning exzellently now for about 6 years and those fools never appeared again.

I discussed this with my tech and he told me that the buzzing I described in the former thread could of course very likely derive from that same bad soldering work ( or completely unsoldered point) on the the second red as well, as my described failiure looks like an insufficiant or self initiated switching between "Clean" and "Lead" mode.
We also assume the pin on both amps had been soldered originally only on the rearsided printed circuit but either it can be insufficiant or the trespass from one side to the other might be wrong.

Now my question and asking to all Mark III owers, and especially with the red stripes:
Would you please be so kind and show a magnified pic of that optocoupler of your amp if you have some at the ready,
or can you tell all us Mark III owners if that pin is soldered correctly on your amp or if you had strange behaviours with your sound in the past ????

My last guitar player will come along next week with his camera and I also will take some pics and hope I`ll succeed in to show them here.

Thank you SO MUCH in advance.

 

[megavoice]

No interest ?...........well,,,,,,,,,strange,.........or even ominous.......................

 

[Agustín Collia]

No interest ?...........well,,,,,,,,,strange,.........or even ominous.......................

I was waiting for you to post the pictures, so that I can check my Blue Stripe! I can't really locate the coupler you are referring to.

 

[megavoice]

Thank you
My man will come along with his camera on friday and then I`ve to find out how to insert the pics here.
If it doesn`t work I`ll give you more and pricise details which one it is. But I it`s very likely that one that switches between LEAD and CLEAN.

 

[Agustín Collia]

Thank you
My man will come along with his camera on friday and then I`ve to find out how to insert the pics here.
If it doesn`t work I`ll give you more and pricise details which one it is. But I it`s very likely that one that switches between LEAD and CLEAN.

Thanks! I think you can't attach pictures directly. The best way would be to upload the pictures to a host (like Picasa or Imageshack, even Facebook) and then paste the links to the pictures in your post. Good luck!

 

[megavoice]

Thank you
My man will come along with his camera on friday and then I`ve to find out how to insert the pics here.
If it doesn`t work I`ll give you more and pricise details which one it is. But I it`s very likely that one that switches between LEAD and CLEAN.

Thanks! I think you can't attach pictures directly. The best way would be to upload the pictures to a host (like Picasa or Imageshack, even Facebook) and then paste the links to the pictures in your post. Good luck!

EXCELLENT ! You`re a shore in the desert. I`m not at at all skilled with these things, but now I hope I can get through.

 

[loylo69]

I hadn't answered yet, because I couldn't see how I could be of any help unfortunately.
The soldering is no longer original in my redstripe III as I had redone all the solders while servicing my amp in the past.
So it would be irrelevant to show you pics of my amp.
But I can't remember seeing unsoldered components on any IIIs I had serviced.

However, I don't think the vactrol behind the lead volume would be responsible for the "buzzing/intermittent distortion" problem you've described.
This vactrol is only supposed to connect the lead volume pot into the circuit while switching to lead mode. So if it were intermittently "working", it would only result in a volume burst/cut.
The failure you described would rather be caused by the vactrols which switch the lead preamp gain stages in and out. They are the ones behind the mid pot and the master pot.

Anyway, I feel it would be much simpler to resolder the pin like you did on your other III.
Maybe you already did that ?

 

[megavoice]

I hadn't answered yet, because I couldn't see how I could be of any help unfortunately.
The soldering is no longer original in my redstripe III as I had redone all the solders while servicing my amp in the past.
So it would be irrelevant to show you pics of my amp.
But I can't remember seeing unsoldered components on any IIIs I had serviced.

However, I don't think the vactrol behind the lead volume would be responsible for the "buzzing/intermittent distortion" problem you've described.
This vactrol is only supposed to connect the lead volume pot into the circuit while switching to lead mode. So if it were intermittently "working", it would only result in a volume burst/cut.
The failure you described would rather be caused by the vactrols which switch the lead preamp gain stages in and out. They are the ones behind the mid pot and the master pot.

Anyway, I feel it would be much simpler to resolder the pin like you did on your other III.
Maybe you already did that ?

Thank you for your post, but as I said my first amp showed up a behaviour and changing functions and the tone colour like a "Chameleon" previously. Extreme distortion, little distortion, ultra long lasting and high intensive reverb or no reverb, a.s.o.
All what is happening now looks very similar. I`ve to admit it`s not only the buzzing, LEAD sound is changing also from time to time........
As I said also, after soldering that bloody pin on the upper side on the PCB on my first, all misbehaviours disappeared from one moment to the other and that amp is working GREAT now.
I don`t want to do anything, before having done some pics as I want to have a piece of evidence now.
But before soldering I`m going to push a small needle in that gap between the pin and the edge of the spot eye the pin is into in order to "force" a firm contact, but only as a first check......

My man hadn`t time today to come by as he`s very busy, so the whole thing will delay for about one week, I hope so.....