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At what point do you give up on a repair?

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    gearhead63
    Member

  • gearhead63
    replied
    Originally posted by Enzo View Post
    Whenever I have a Crate on the bench, I go through ALL the jacks. They use the Cliff style jacks. And most have cutout contacts, so I carefully measure the RESISTANCE between the cutout contacts. If it is more than HALF an ohm, I consider it a problem. Two ohms sounds good, after all what can 2 ohms interfere with? But it SHOULD have close to zero ohms, and the fact it sits there at 2 ohms tells us the contacts are not pristine, and can just as easily go higher from time to time. This solves the complaint of a Crate dropping output level now and then, and the FS jack causing unwanted random channel switching, all by itself.
    YES SIR! I do the exact same thing! In fact I've had a few Marshalls that wouldn't power the speaker, but the headphone/out jack worked. Damn Cliff jacks!
    And yea, it REALLY sucks when something just bites you in the a*s and won't cooperate. A lot of the time, I'll still try to figure out whats wrong and repair it, because if you learn something from it, then you didn't waste your time!

    Leave a comment:

  • glebert
    Supporting Member

  • glebert
    replied
    I have a Trace Elliot bass head that I am going to have to give up on and it really ticks me off. I bought it as a fixer, found the Bipolar Bear power amp module was totally fried. It was not the first time it had burned up, so many traces were obliterated, etc. I found a class D amp module that was a great fit for it, so I wait 6 weeks or whatever for it to come from China. I installed it and it worked well at first, but there was some preamp hum. As I get ready to start diagnosing that it starts popping fuses. It looks like the PT must have developed an internal short (bright LBL with secondaries disconnected), maybe it is only after it is warmed up or something, but basically that puts this into the not worth fixing file.
    glebert
    Supporting Member
    Last edited by glebert; 11-17-2020, 11:49 PM.

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  • Leo_Gnardo
    Old Timer

  • Leo_Gnardo
    replied
    Originally posted by Mick Bailey View Post
    as a friend used to tell me, "If you're trying, you're not doing".
    Is this your friend?

    Click image for larger version

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    It's one of my not-so-favorite wastes of time, flogging a piece of gear until it's hopeless. But I do it anyway. Sometimes a crustomer loses patience & takes it away. In other cases the customer has an awful lot of patience. For instance I had a recalcitrant powered subwoofer that would not yield. It sat around here for over 3 years, hogging half a cubic yard of my space. When the customer eventually signaled he wanted to pick it up no matter what, I gave it one last attempt. And this time, I won! Turned out to be something easy simple & cheap. I had overlooked those options the first couple times around. He was delighted. And now he's serenading his neighbors with boom boom bump-diddy-ump.

    Leave a comment:

  • Mick Bailey
    Supporting Member

  • Mick Bailey
    replied
    My basic rule of thumb is that if the repair exceeds 50% of the replacement cost then it's not economical unless the customer has a very special reason to spend whatever is needed to fix it. I usually take a look just to be certain the fix isn't going to be dead simple and I may be missing something. How many hours can you put into fixing a looper pedal that cost $25?

    Sometimes though the reward is tantalizingly just out of reach and I recently put an absurd amount of time into trying to fix an Ernie Ball/Music Man Majesty guitar. And as a friend used to tell me, "If you're trying, you're not doing". I could see exactly what was happening but the problem is the factory only replaces boards and couldn't offer any in-depth technical help. I gave up on that one because the boards were only available to me at full retail and the cost was too high for me to want to guarantee the parts.

    Leave a comment:

  • Enzo
    Lifetime Member

  • Enzo
    replied
    Whenever I have a Crate on the bench, I go through ALL the jacks. They use the Cliff style jacks. And most have cutout contacts, so I carefully measure the RESISTANCE between the cutout contacts. If it is more than HALF an ohm, I consider it a problem. Two ohms sounds good, after all what can 2 ohms interfere with? But it SHOULD have close to zero ohms, and the fact it sits there at 2 ohms tells us the contacts are not pristine, and can just as easily go higher from time to time. This solves the complaint of a Crate dropping output level now and then, and the FS jack causing unwanted random channel switching, all by itself.

    Leave a comment:

  • glebert
    Supporting Member

  • glebert
    replied
    I was working on an amp today that I refer to as Schroedinger's Crate. It is a GT80 DSP that would lose most of its signal after it warmed up, but if you sat on the cabinet or touched a push button or something it would be OK for a second. Get it opened up and am chopsticking around looking for a cold solder joint and anywhere you tap would send it in or out of the fault state. Touch a wire harness? Changes state. Probe a pin? Changes state. Finally pulled the board and reflowed pins on the tube closest to the output section. Seems like it might be stable now. This amp really isn't worth the hassle of multiple tear-downs, but I really hate junking stuff that can be fixed. I figure if I spend enough time poking at it I will get it eventually.

    Leave a comment:

  • g1
    Don't forget the joker

  • g1
    replied
    I think when you get to the point where the actual board can be defective, those kinds of equipment I tend to quickly 'skim' for simple faults and then give them a pass if it's not something simple. Like double sided with lots of via's, or triple layer, or even the bad run of Marshall TSL boards. People do the TSL's now because someone went to a lot of trouble to discover the faults and there are known work-arounds. Otherwise it would not be economically feasible.
    I'm thinking particularly of stuff like line 6 where they used to want you to do board swaps because they knew an internal fault of the actual pcb was possible.

    Aside from that I'm with those here who see the real tough ones as a form of education.
    And nothing more satisfying than finding the fault on something that has done the rounds to several reputable shops and no one else was able to fix it.

    Leave a comment:

  • nosaj
    Master Destroyer

  • nosaj
    replied
    Bing Bing Bing....hidden nugget alert.....

    Resorted to using Freeze mist to freeze the screw head, and was able to break the bond and not the screw, finally getting the cover off.


    Cool trick

    nosaj

    Leave a comment:

  • nevetslab
    Supporting Member

  • nevetslab
    replied
    I just gave up on a repair this morning. Aguilar Tone Hammer. The complaint was the Midrange Frequency Pot wasn't working. Verified that in closed-box checkout, so proceeded to attempt removing the top cover. Tiny Philips #1-size FH SMS's used. Got all but two screws to break their bond and unscrew...last pair would have stripped out the Philips pattern. Resorted to using Freeze mist to freeze the screw head, and was able to break the bond and not the screw, finally getting the cover off. The front panel PCB....loaded with SMD parts and thru-hole panel pots soldered into both sides of the double sided board, along with switches and LED's.

    Getting the board out required backing out the screws holding the shield wall between that board and the combined SMPS/Class D PCB assembly. Got the board out, took a bit of time unsoldering the Lead-Free solder joints of the dual gang Freq Tuning pot. Finally got all six leads to wiggle, having removed all but the solder within the plate-thru holes clinging to the leads, and removed the pot. Applied contact cleaner to both resistance wafers, and verified both elements work. Put the pot back in, reassembled the unit (PITA), and put the cover back on with just a few screws attached. No change...Freq Pot still not working. Pulled the top cover off again, verified the top side of the PCB's pot terminal traces wandered into the cluster of SMD caps and resistors, nothing broken on the top side traces. No documents, and too small to want to spend any more time. Put the cover back on, returned it to the Guitar Dept to send back to Aguilar back east. I should have stopped before even pulling it apart, but wanted to at least say I tried.

    Leave a comment:


  • Arbutt
    replied
    Well ive been playing around with amps for years, Not really an electronics engineer, have had a few dead end jobs where i have learnt some skills
    I'm getting busier slowly every year, filling a void in my area where. I use to take on everything and anything, but this has caused me lately to want to stop. I ---- work to live - not live to work
    I have stopped doing modern hifi amps , AV amp mostly and any amp that i am wary of i will take a look and if looks like a pile of pain, I had back... Only in 10 yrs have i given back a valve amp un repaired
    I have in the past priced a repair up hoping he says no and he says Yes

    Keep up the good work and its always a pleasure learning from you guys

    Leave a comment:

  • Enzo
    Lifetime Member

  • Enzo
    replied
    I can fix anything. I say that, and I believe that. It doesn't always make sense to do so, sure, but I know if there is a solution, I will find it, or invent it. I don't like to give up because I want to solve the puzzle.

    Leave a comment:

  • Axtman
    Supporting Member

  • Axtman
    replied
    There is a psychology in gambling where people will pay a person to guard "their" slot machine while they go to the bathroom. They will also sit for hours at a losing machine because they have got to win eventually, right? Wrong! They have no better odds at one machine or another. The problem is that they have invested $500 worth of quarters in that one machine.

    That kind of happens to me. The more I work on an amp, the more I want to repair it because I have invested so much time and effort. It really pains me to give up. When I do I get rid of the amp quickly usually at a loss. I don't keep it around because I don't want that LOSER trophy hanging around reminding me of my failure.

    I am trying to keep a positive attitude and reminding myself that I am learning something about the circuit or repair technique even if I did not fix it.

    Leave a comment:

  • Enzo
    Lifetime Member

  • Enzo
    replied
    Customers can be crazy. Once a customer and friend brought me an amp. He just sits strums and sings, and was using an old Sansui stereo amp for a PA. It was blown up. He was going to need output transistors and other stuff and an hour or more labor. I said, "Jerry, you can just buy another one of these down at the pawn shop for $45, save some money." He said, "Well that is where I bought this one and that is what I paid for it." But he likes it and wanted me to fix it anyway. Oh well.

    Leave a comment:

  • gui_tarzan
    Senior Member

  • gui_tarzan
    replied
    Originally posted by Enzo View Post
    For every puzzler I get to learn from that takes way too long, there are plenty of times just experience and systematic thinking get me to the solution is VERY short order.

    Experience counts in many ways. MY pal invited me and the wife over for pizza one time. WHen we got there instead of a dinner plate, in front of me on the table was a Peavey Classic 30 chassis. HAving previously boasted I could have the boards out in a very few minutes, he called me on it, said I had to prove it for my dinner. The first one I ever did was a pain, but after a couple. a snap. SO six or seven minutes later, voila boards out.
    That is awesome.

    This isn't just the case in amp repair but in everything. There is a point where salvaging the original isn't worth it - unless the owner has an unlimited budget and an emotional attachment to it. In IT it is typically 40% of the purchase price is the cutoff. After that it doesn't pay to fix it.

    If you have an amp like a Blackstar I worked on quite a while ago that burned several components it can be a challenging decision. When I was unable to get the schematic for it to identify the parts needed and couldn't get info from the company (it was well out of warranty) I returned it to the owner. I wasn't going to guess, especially with a circuit board that was questionable. I'm sure the owner wasn't happy that the amp he spent a lot of money for would have taken another lot of money to fix because of restrictions by the company.

    Leave a comment:

  • DrGonz78
    Stray Cap

  • DrGonz78
    replied
    The question is how far down the rabbit hole are you willing to go for a customer? Many times the problem is that you don't necessarily know it's a rabbit hole until your already in it and by then it feels defeating to turn back. My rule of thumb is if the item is for a close friend or something I own then I pursue deeper into those head scratching repairs. I have had a few customers realize that some piece of gear is just a lost cause and they give me the unit for spare parts. For those customers there is a new appreciation that is created by this interaction and they learn real quick not to bring certain repairs in the first place. I can name four amps that caused me trouble... Crate GT200D, Reverb tank squeal on a Vox Cambridge amp, Epiphone EP-800, and Line 6 Spider II. Those were my rabbit holes that I ran out of time or had to give up on the repair. The Epiphone is still sitting around and I may open it up again to work on it. Also I still have the Line 6 amp and will give it another look soon. I might just gut the digital preamp stuff out on that Line 6 amp and just install some sort of simple preamp to feed to the working power amp, just for fun.

    Leave a comment:

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