Mr Grumpy
Ambassador of Comings and Goings
Amplifier service
- Thread starter RVA
- Start date
jtcnj
Ambassador of the Crossroad
See that big green thing in all the gut pics?
The pcb.
Since you swapped out tubes, now this is not about the tubes.
Any bad solder joint or failing component can give you make you crazy intermittent problems, tubes or not.
including tube sockets whether board mounted or not.
I repaired my brother's ss -a traynor something but branded different - that had a crackle scratch hiss vicious noise that seemed centered around the board mounted input jack.
Cracked solder joint from use / abuse.
next, odd popping crackling isolated to one of the pots - but only after really jiggling them around ie it was not apparent just turning the pot.
bad solder joint on board mounted pot.
reflowed both and that amp has been solid ever since, or since I last heard.
So either way, the more complicated and more components the more places that can be troublesome.
The pcb.
Since you swapped out tubes, now this is not about the tubes.
Any bad solder joint or failing component can give you make you crazy intermittent problems, tubes or not.
including tube sockets whether board mounted or not.
I repaired my brother's ss -a traynor something but branded different - that had a crackle scratch hiss vicious noise that seemed centered around the board mounted input jack.
Cracked solder joint from use / abuse.
next, odd popping crackling isolated to one of the pots - but only after really jiggling them around ie it was not apparent just turning the pot.
bad solder joint on board mounted pot.
reflowed both and that amp has been solid ever since, or since I last heard.
So either way, the more complicated and more components the more places that can be troublesome.
I am hearing more and more people talking about Axe-FX in professional circles.
67plexi
Ambassador of Amps
Ray I can tell you how I would start troubleshooting or how I was trained
1 primary voltage into power transformer
2 secondary voltage out of power transformer. Transformers are AC voltage
3 after diodes it will be DC voltage B+1 to filter caps and stndby switch and choke and power to primary output transformer
4 check pin 3 power tubes and pin 6 if it's EL34 make sure pin 7&8 are grounded
5 pin 1 & 6 phase inverter should be around 300 VDC 12AX7 50% of the time this tube will fail first and what it does is connect the pre amp to the power amp.
6 pin 1 & 6 all pre amp tubes all to V-1 input.
Write down all voltages in the order I posted. B+1 through B+4 is your dropping string say B+1 is 465V then a resistor to B+2 300V and so on.
1 primary voltage into power transformer
2 secondary voltage out of power transformer. Transformers are AC voltage
3 after diodes it will be DC voltage B+1 to filter caps and stndby switch and choke and power to primary output transformer
4 check pin 3 power tubes and pin 6 if it's EL34 make sure pin 7&8 are grounded
5 pin 1 & 6 phase inverter should be around 300 VDC 12AX7 50% of the time this tube will fail first and what it does is connect the pre amp to the power amp.
6 pin 1 & 6 all pre amp tubes all to V-1 input.
Write down all voltages in the order I posted. B+1 through B+4 is your dropping string say B+1 is 465V then a resistor to B+2 300V and so on.
RobV
Ambassador of Bedroom Wankery
Ok I lied, it's not working fine, thought I would check this morning, turned the surge protector back on and same issues, turn the stand by on and I hear not good feedback in the amp and no power light. I am sure if I flick the switches a few times it will come back on eventually and when it's on properly it doesn't cut out
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jtcnj
Ambassador of the Crossroad
@RVA Was that Panama too loud to crank up a bit into overdrive?
My 5w 5f1/5f2a modded thing starts some good OD at around 10:00 vol with hottish P90s or PAFs,
through an 8" low efficiency weber ceramic Sig 8.
Gotta wind it up a bit more with vintagey wound strat singles, the overall volume is a bit higher, but in either case:
It is somewhat loud but not LOUD LOUD. Sweet singing tube OD....
and push with clean boost / treble boost or Klonish type low gain pedal - best tones I have heard from my gear so far.
just this past Friday (last time I played unfortunately ) it started making some popping crackling with no guitar plugged in and indifferent of volume / pot settings. tapping on the cab with my fist (rattle test) yielded more symptoms
chop stick / Tap test revealed more symptoms occur at power tube and rectifier.
Pulled and reseated power tube a few times cleared it up. repeated for rectifier and single pre amp tube for good measure.
I am jonesing to play real bad and we will see what happens by around 6:00 PM EDT.
But methinks any good quality ss along with your array of pedals will serve you well.
Just keep in mind, this misfortune occurred with a tube amp, but may not be because it is a tube amp vs. ss.
I would not want this incident to unfairly prejudice the counselor's objectivity.
My 5w 5f1/5f2a modded thing starts some good OD at around 10:00 vol with hottish P90s or PAFs,
through an 8" low efficiency weber ceramic Sig 8.
Gotta wind it up a bit more with vintagey wound strat singles, the overall volume is a bit higher, but in either case:
It is somewhat loud but not LOUD LOUD. Sweet singing tube OD....
and push with clean boost / treble boost or Klonish type low gain pedal - best tones I have heard from my gear so far.
just this past Friday (last time I played unfortunately ) it started making some popping crackling with no guitar plugged in and indifferent of volume / pot settings. tapping on the cab with my fist (rattle test) yielded more symptoms
chop stick / Tap test revealed more symptoms occur at power tube and rectifier.
Pulled and reseated power tube a few times cleared it up. repeated for rectifier and single pre amp tube for good measure.
I am jonesing to play real bad and we will see what happens by around 6:00 PM EDT.
But methinks any good quality ss along with your array of pedals will serve you well.
Just keep in mind, this misfortune occurred with a tube amp, but may not be because it is a tube amp vs. ss.
I would not want this incident to unfairly prejudice the counselor's objectivity.
67plexi
Ambassador of Amps
For a little extra they have a load box you can have all your amps in the AXE-FX-3 I have the money but I save my gig money to buy and I
have had the flu this month so canceled all my gigs if I don't have the extra cash to buy I don't.
jtcnj
Ambassador of the Crossroad
Take care and get well soon!!
OP
RVA
Ambassador
Cursory diagnosis by the amp tech is the output transformer. Then I called Mercury Magnetics, and, rather than make a sale, they said it might be the power supply and suggest i take it to a tech instead of buy their product. You cannot beat that kind of honesty. GO MERCURY MAGNETICS!!
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Plexi, I don’t thats the Evil Twin. The 1994+ Evil Twin version should look like this.
syscokid
Ambassador of War & Peace
When you mentioned a few posts ago that your amp would clear up after you quickly flipped the standby switch, that to me makes me think that it's somewhere in the power supply. This is the area where I outlined over your photo that I reposted. When the good people of Mercury Magnetics suggested "power supply", did you tell them what happened when you flipped the standby switch?
That big resistor(ceramic) in that block that you drew out is where a choke could be, if I’ve read correctly. Just speculation from a little light reading...maybe a problem spot in the tail end of the power supply section...thermal/current related.(they used a big ceramic resister there, instead of a choke-cheap way to an end)
Ray, this is the JVM 50 watt head, right? The board says 410, but it’s actually the 205?(I don’t mean to be a pain/slow on the uptake)