Help for a VOX solidstate

[allante666]

I had about five minutes spare last night just to double check that it reaslly didnt do it through the headphones. I switched it on an dafter a minute or so it started crackling, I instantly put headphones in and lo and behold no crackles through the phones! I did this enough times to rule out coincidence, Im pretty sure its not the socket itself but i wil check it later. Im going to substitute another speaker this weekend, Ill let you know how i get on.

[J M Fahey]

Hi allante

I did this enough times to rule out coincidence,

That was important, many times we run in circles trying to find a solution based in not-so-sure information.
I'm quite certain that it's a speaker problem, then.
Ultra flexible speaker wire is really very fine regular copper tape, wound spirally on cotton threads.
With vibration or abuse (read drop-D tunings, palm muting chest shaking, etc) or too much bass on open back cabinets, they start to crack, but don't fully fall apart because of the cotton thread core, so they become intermittent following the music= crackling noise.
The other possibility is that some very tiny iron speckle got attracted into the gap where the voice coil lives.
Test both speakers separately (just unhook 1 lead from the one silenced), you will probably have that problem on only one of them, it's extremely unlikely that it happens on both at the same time.
Good luck.

[allante666]

Yes, ive made the mistake before of trying something only a couple of times and thinking it 'cured' it only to find out that it was just chance that it worked. If a replacement speaker cures it I will also try the vox speaker in another amp as a double check to se if the crackle goes with the speaker. I dont recall the speaker wires being the type you describe I think they were ordinary wire with spades on. Dont forget mine is not one of the old AC amps it a very modern VT one with a very modern build quality! Just realised im in someone elses thread which is why i was slightly puzzled when you suggested it had two speakers! mines a VT50 it only has one. However, same problem same cure hopefully! watch this space....

[J M Fahey]

Hi allante.
I was not referring to the wires that connect the speaker(s) to the jacks, which are of the regular kind, but to the ultraflexible *internal* ones, that go from the speaker terminals (fixed to the frame) to the voice coil itself, which dances more than a happy Irish, back and forth thousands of times a second pushing the cone.
*That* is heavy work !!!!!!!!!!!!!
Most people are unaware of them, because they are hidden between the frame and the cone.
I had also thought you had a 100W 2x12" combo, anyway the test applies to it too.
Good luck.

[allante666]

Yes I know th eones you mean now. I turned it on tonight, poised with a cab lead ready to push into the external speaker socket the minute it started and .... it didnt do it! sods law huh! Ill keep giving it a try, its bound to do it one time!

[J M Fahey]

Don't forget Murphy's Law, the only real Law in the Universe.
Of course that as long as you stay close with a cable in your hand, it'll work flawlessly.
Didn't see the Mister Bean episode where he buys a TV set ?

[allante666]

Hmm, dang thing has been working flawlessly all day! despite having some heavy duty bass played through it.
I think maybe Ill leave it on and creep up on it in the dark, try and surprise it. Im fighting with a behringer in another thread now so the vox may start to feel left out and start playing up
Its years since i watched Mr Bean, I do seem to remember one where he cut a serving hatch in his wall, cant remember what happpened but i remember it being really funny! something to do with moving a table. then there was the one where he ran out of twiglet snacks so coated a real twig in marmite....

[Ronsonic]

Like the man said, CHECK THE HEADPHONE JACK. Not does it send signal to the headphones, but does the switching inside the jack that interrupts the output work correctly. Is the jack properly soldered.

[AnnMar Studios]

I second that. I did the same thing and I do not have the same issue through the headphones.

bizzare.

[olddawg]

Like the man said, CHECK THE HEADPHONE JACK. Not does it send signal to the headphones, but does the switching inside the jack that interrupts the output work correctly. Is the jack properly soldered.

It seems that it started working after you plugged and unplugged the headphone jack a couple of times. I would hard wire the headphone jack out of the circuit and see if it cures your problem. At least spray the damn jack with DeoxIt and jockey the plug a few times.

[allante666]

No, as I previously said I had cleaned and bypassed the sockets (bad choice of words I guess, I mean I had temporarlily wired across them to rule the switching contacts out as well as deoxit'ing and working a plug in them all before that), I did this to the headphone as well as the ext speaker jack. Its still working fine so far. It worked like this for two whole days after I resoldered it all then suddenly started crackling again. I can wait....

[allante666]

switch it on every day, leave it on fro various lengths of time, move it around, thump it, STILL working perfectly! I just know if I sold it that it would start again. Ill end up adopting it as my own at this rate!

[R.G.]

switch it on every day, leave it on fro various lengths of time, move it around, thump it, STILL working perfectly! I just know if I sold it that it would start again. Ill end up adopting it as my own at this rate!

... or it was the headphone jack, and all the plugging/unplugging headphones has temporarily cleared the crud enough to let it make contact now.

Intermittent contact issues are ... devious. Sometimes doing anything at all to them will clear the fault.

Clean all the contacts, especially the headphone one especially well, and ship it. Tell the owner what you did, all the due dillligence testing and fixing on it, and how it now doesn't do it at all. Maybe offer a modest discount. If it comes back, be especially nice and kind to the owner and make the owner happy with service. That is, it may never fail again, so let the owner use it for the time it does work properly.

[allante666]

It doesnt have an owner as yet, other than me of course.
If I thought it may have been a jack I would just renew all of them but I know it isnt as I have hardwired them and still had the problem. Im quietly convinced its the speaker but until it does it again I cant prove it. I wouldnt sleep at night selling it and knowing it might just do it again.
Its not a problem if I do keep it myself for a while, I tend to change my own amp depending on what comes in to repair. I dont repair for customers, only for resale so it doesnt really matter. Its just a shame as its a really clean one and would fetch a good price.
Still..good things come to those who wait..

(50 years, and still waiting!!)

[R.G.]

Im quietly convinced its the speaker but until it does it again I cant prove it.

Divide and conquer. Put the speaker on a different amp and run it. Put a different speaker on this amp and run it. Make the two channels be left and right on the shop radio/background music.

I wouldnt sleep at night selling it and knowing it might just do it again.

That's reasonable and responsible, if that's all there is to it.

But remember that eventually, *everything* fails. Newly manufactured *anythings* fail. That's what warranties are for. Warranties don't make things not fail, they just limit the financial exposure of the buyer for a time.

So convert it to being the source for the shop's background music, and play it all the time you're in the shop. Maximize the chances for it to fail. Or set yourself a time limit: if it hasn't failed after X hours, you have fixed it by the poking around. That does happen, especially with dirty contacts. Test speakers and amp in separate channels.

Or sell it at a discount, after full disclosure, and a guarantee to fix it if it breaks before some reasonable time.

Or decide to keep it. Works either way.