Blackstar Series 104EL34 snap, crackle, pop issue

Discussion in 'Gear & Equipment' started by Mourguitars, Jan 9, 2020.

  1. Mourguitars

    Mourguitars SS.org Regular

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    Like the title says , last night i was playing and lost gain on Crunch , OD1 and OD2 and even with the noise gate on i developed that static crackle sound..First i thought it might have been a cable or a jack or pedal issue...so shut it off.

    Checked all cables, pedals with a different amp..all was fine no issues on my HT-20 head that's giving me no problems what so ever..got it on a trade. Its sterile sounding but a EQ in the loop livings it up

    Today i googled the issue and it seems to be common problem on these amps with some people changing pre amp tubes and power tubes ...some with success fixing the problem..others not so

    Pulled out of the head shell after my simple cap discharge by playing a chord and pulling the plug out of the wall ( disclaimer i read this on a few forums, but discharge caps correctly ) looked around with a flash light and strong glasses to see if i had a bad solder joint or something burn on the PCB..all looked good to my eyes..once again i cleaned all speaker, effects loop and input jack, snapped a few pics....Dials are smooth but twisted them back and forth a dozen tines each incase they got burnt into a certian spot

    Pulled the tubes cleaned the pins..sprayed my electrical Deoxit on the pins and worked them in the sockets gently and repeatedly to do a simple clean on all sockets, all were very snug... let dry out for 30 min and put them in , fired it up and same problem.

    Have a new quad of JJ;s and new pre amp tubes...put them in ...and same snap and crackle....

    Again this seems to be a common problem with this issue. on these amps..there is no one around that can fix these that i know of ....any info on google is vague and sparse ..its 10 years old but in great shape, but maybe some of you amp builder repair tech guys might have a suggestion ? Hate to have this as a big paper weight !

    Mike


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  2. Edika

    Edika SS.org Regular

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    If you don't hear the pop and crackle on the clean channel it seems to be coming from the preamp valves. If it's not the tube itself it might be an issue with the tube socket itself, either a connection issue on one of the leads or it might need replacing alltogether. The other issue could be a cap going bad which would cause these sound issues. I'd suggest taking it to a tech to look at it.
     
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  3. Mourguitars

    Mourguitars SS.org Regular

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    Good advice Edika....i exhausted my limited troubleshooting experience , spent a few more hours visually inspecting and V4 and V5 pre amp tubes just isn't glowing like the other 3...i rolled a lotta tubes in there ...still the same. The old stock tubes i have that are good made those channels dark and no gain. Rolled the tungsols and JJ's..brightened up again but no sustain but the amp seems to like JJ's

    Either have a cold solder joint or the sockets are dirty or bad but i can't see the solder joints from the side im looking at , but that Pre amp section PCB is pretty assessable and easy to take out...BUT im not getting anywhere near those caps !

    Ill make some call's today , but the guys I've trusted doing repairs i dont know if they are in the area anymore

    Mike
     
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  4. Mourguitars

    Mourguitars SS.org Regular

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    On the last pic , one of the caps on the right side by the + is broken loose...the old owner had it shipped from GC the box was dropped during shipping but it was shipped in a flight case...ordered new tubes and taking to a tech Friday...even tho i drained caps....and maybe a simple fix or re-solder...ill have him go thru it check everything out

    Taking Edika's advice...when i tested the volts on the caps before i drained them that one was low...Good caps was 398v the bad was 276v

    Mike
     
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  5. Mourguitars

    Mourguitars SS.org Regular

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    *****Update****

    My trouble shooting was spot on , it was that Cap that broken loose / bad solder joint combo in case anyone else stumbles across this post...it may help with your problem. Tech replaced the cap since he was in there...cost $100...well worth it.

    Mike

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  6. Mourguitars

    Mourguitars SS.org Regular

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    Fixed , re tubed and biased......

    I tried JJ's , Svetlana, EHX and the reg pin Glenalex (china) 12ax7's those were bright but settled on the Gold Lion CV4004's in the pre amp....it tamed that harshness

    Time to put it back in the headshell

    Mike

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