Hello guys, a couple of weeks ago i took two amps from a friend, both were in someones else repair “bench”, this is what my friend told “ amp was bought as a bargain, took it to a guy to install the fromel kit, after that amp has NO preamp, and also switching its sketchy (when push change channel light turns red it’s supposed to be yellow, and when you press more drive its glowing lighter then completes turns of) so this is what i have done
~ cleaned all solders and repaired some burned trails
~checked all components and steps on the fromel kit, they tested ok and they are all correctly installed.
~ i measured R78 R79 im reading 47.8v from one side which is good, but am reading 3.0v and 2.9v from the other side so all low power supply its wrong.
~im not getting readings from U1 just the same reading on pins 4 and 8 3.0v 2.9v
~ i did change Q4 channel switching behave ok but its again down, maybe other component its shorting taking Q4 down?
~i do have clean audio on power amp in/send , so i do suspect problem is on switching related, also i did not notice anything else in bad shape.
As a note im suspecting this amp was already on bad shape, I don’t think the last guy repaired to stock condition and then modified, i do think somehow he was hoping after the mod the amp worked, anyways now its my problem so let me know if you guys can chime in with some ideas, thaaanks a lot
~ cleaned all solders and repaired some burned trails
~checked all components and steps on the fromel kit, they tested ok and they are all correctly installed.
~ i measured R78 R79 im reading 47.8v from one side which is good, but am reading 3.0v and 2.9v from the other side so all low power supply its wrong.
~im not getting readings from U1 just the same reading on pins 4 and 8 3.0v 2.9v
~ i did change Q4 channel switching behave ok but its again down, maybe other component its shorting taking Q4 down?
~i do have clean audio on power amp in/send , so i do suspect problem is on switching related, also i did not notice anything else in bad shape.
As a note im suspecting this amp was already on bad shape, I don’t think the last guy repaired to stock condition and then modified, i do think somehow he was hoping after the mod the amp worked, anyways now its my problem so let me know if you guys can chime in with some ideas, thaaanks a lot
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Okay, thank you. Looks like you need a marked-up schematic to show what the fromel kit does to the circuit topology. Do you expect us to do the work, or who do you think it would be best to do that?
BTW, I'm not asking you to do something I wouldn't do myself. I sketched up a schematic of an as-built Mesa Booking MkII-C after Mesa swore to me they didn't have a schematic for that version. They said they just knew how to build them at the time when they did because they knew the procedure in their heads, but never documented it.
Also, assuming you are used to working with tubes, have a scope, signal generator, etc., right?
BTW, I'm not asking you to do something I wouldn't do myself. I sketched up a schematic of an as-built Mesa Booking MkII-C after Mesa swore to me they didn't have a schematic for that version. They said they just knew how to build them at the time when they did because they knew the procedure in their heads, but never documented it.
Also, assuming you are used to working with tubes, have a scope, signal generator, etc., right?
ok by the answer you’re the type of member that aint going to help, i read the unedited answer you gave me, and people like you are the reason why i hate to ask help in forums, what do i expect?, i expect that you READ the problem, if you’re familiar with the model maybe give some pointers or help since Fender has a lot of common problems by model like all the other times i have ask for help and other members gladly helped, if not just move on pal, im doing this as a favor i do not do this as a job, im not expecting someone on internet do a “job” for me neither, im in a country waaay to far to be any techs around and i have built, rebuild, modded and upgraded tube amps in the past with 100% succed (who cares right?), i just dont do it anymore thats why im looking for help here since I don’t want to spend too much time in a favor like i did so many times before, i been in forums for way to long and theres always the members that gladly help and theres the others that act like all its to complicated and have some “teacher ego syndrome” preaching and gatekeeping electronics not helping in nothing at all, and the fact that you even edited with some random anecdote about a Mesa amp, really pal? How that help me? Have fun the link its detailed with whats been affected by the mod you just didn’t read or care about what i wrote your were more concern on your Mesa anecdote, so like i said just move on to other threads, believe me you don't help me and you wont and thats fine with me, im looking for help not more trouble if not whats the whole point of this forums, no bad blood just to tired of this type of forum members if im having a trouble don’t add yourself as another one, have a good one
Bye.
Bye.
I opened the thread to help but the level of ENTITLEMENT and LAZYNESS you show are above normal so good luck with your project.
Diverging with what real Techs suggest, you do not really need scopes, generators or any kind of instrument, not even a humble multimeter, because Fromel instructions are as basic as can be, simple "paint by the numbers" type. 👍
Why do you ask US at all?
Just follow them faithfully to the smallest detail and you will succeed.
Yes, even you, that's how simplified and "robotic" they are.
Kudos to Mr Fromel for catering to the lowest common denominator, it shows Compassion.
Now "anybody" can claim "I am an amplifier modder" ... how's that? 👍🏻
And: "I don't need no d*mn Forum help"
Diverging with what real Techs suggest, you do not really need scopes, generators or any kind of instrument, not even a humble multimeter, because Fromel instructions are as basic as can be, simple "paint by the numbers" type. 👍
Why do you ask US at all?
Just follow them faithfully to the smallest detail and you will succeed.
Yes, even you, that's how simplified and "robotic" they are.
Kudos to Mr Fromel for catering to the lowest common denominator, it shows Compassion.
Now "anybody" can claim "I am an amplifier modder" ... how's that? 👍🏻
And: "I don't need no d*mn Forum help"
Well, I'm not much of an expert but it would seem to me that you isolate which section isn't working.
Switching is by relays so by isolating the coils by lifting nearby components the relays can be switched by external supply.
If the +/- 16v supply is down then isolate each section that it is feeding to see if the supply is faulty or which section is bringing it down.
I fixed an amp with the aid of a £5 signal generator kit off Ebay to find the dodgy section.
For someone with so much experience I'm surprised you're asking.
Switching is by relays so by isolating the coils by lifting nearby components the relays can be switched by external supply.
If the +/- 16v supply is down then isolate each section that it is feeding to see if the supply is faulty or which section is bringing it down.
I fixed an amp with the aid of a £5 signal generator kit off Ebay to find the dodgy section.
For someone with so much experience I'm surprised you're asking.