HELP!! One channel only!

[Deleted]

Can anyone help?
I finally got round to doing Mike’s X-10D buffer stage mods today.
I fitted the new caps, new diodes, new valve bases and fitted a new L.E.D.
However , when I fired her up again I'm only getting sound in one channel, the left.
When I take the buffer out of the system (using just the Dac and Amp) everything is fine so I know its definitely the buffer. Both valves are glowing so I know power is getting to them.
Any ideas as to how I've made an arse of it??

[PinkFloyd]

You won't have made an arse of it, it'll be something very simple like a dry solder joint or maybe a bit of track that has lifted from the pad..... go over every joint with a magnifying glass and do a continuity check (with a multimeter) from one pad to the next.... if any of the joints look a bit "rough" then flood in a bit more solder until they resemble a nice shiny dome.... keep your iron on the joint until the solder flows "into" the joint....... we are looking for lovely smooth domes here, not jagged, rough "peaks".

Also check you have soldered everything the correct way round, the capacitors and the diodes.... it's sometimes easy to solder a cap the wrong way around.

[PinkFloyd]

Pictures of top and bottom of the board will help.

[PinkFloyd]

Also..... never overlook anything.... I once spent "5 days" on an amp only to discover it was an interconnect that was broken

[Deleted]

Thanks, will double check my interconnect though I think its fine.
One thing (and please excuse my ignorance), where and how do I start doing a continuity check?(I have a MM).
Which pad do I start at?
I will load up some photos later, but after checking my joints as you suggested I can see one or two that look a little rough.

[PinkFloyd]

How is it coming on?

[Deleted]

I have connected it up with a pair of I/C’s which I know work, so at least have definitely eliminated that as a possible reason.
I re-soldered 2 or 3 of what looked like poor joints because they weren’t round, shiny domes as you suggested.
I have also carried out what I think is a continuity check, i.e. put the probes across the pads of each individual component. I got readings from all of them. Does the actual readings I got matter? I assume that if I am reading any volts at all then the connection must be o.k. and therefore that is not the problem?
I replaced the new valve bases with the old ones thinking that possibly one of the bases was faulty but problem still persisted, so I put the ceramic ones back in.
I am a bit wary about checking the valve pads themselves with a MM as I believe there are a lot of volts kicking around (or is that just in larger valves like the EL34’s in my integrated?) plus I definitely don’t know the procedure for checking them anyway.
And as I said both valves do light up so I know power is getting to them.
I had thought of de-soldering every single part in the kit and then soldering them back in, and although its a bit extreme, its all I can think of. After that, it’ll be get my cheque book out and send it up to sunny Caithness for some tender loving Pink care.

[PinkFloyd]

To save me typing, here is what a continuity check is:

www.ladyada.net/library/metertut/continuity.html

Probe on one pad.... follow the track along to the next pad and probe on it.... if the multimeter "peeps" you know there is continuity between the two.... if it doesn't "peep" there is every possibility that the pad has parted company with the track....

The blue 220nF caps..... are you sure the legs have actually reached through to the pads? Give them a tug with your fingers and make sure they are actually soldered onto the pads.

[Deleted]

@ Pinkie,
thanks very much for your help, problem solved!
After doing a continuity check, noted that the two diodes on either side of the board at the front(near the L.E.D.) seemed to be at fault.
When I de-soldered the joints, sure enough, the tracks had lifted from the pads. So after flooding the joints with solder i'm back in business! YE-HAA!!
What would I do without Rock Grotto? Thanks Mike!!

[mrarroyo]

All is well that ends well. Cheer!

[PinkFloyd]

Feb 5, 2010 19:06:04 GMT @ekbluesboy said:

@ Pinkie,
thanks very much for your help, problem solved!
After doing a continuity check, noted that the two diodes on either side of the board at the front(near the L.E.D.) seemed to be at fault.
When I de-soldered the joints, sure enough, the tracks had lifted from the pads. So after flooding the joints with solder i'm back in business! YE-HAA!!
What would I do without Rock Grotto? Thanks Mike!!

Nice one

[PinkFloyd]

BTW, if you do happen to lift pads or the pads seperate from the track all you have to do is scrape off the green "topping" from the adjacent track to expose bare copper.... it's then simply a case of soldering the component leg onto the exposed track.

Mike.