Post by thetragichero on Jul 20, 2019 11:40:40 GMT -5
it's baseball season so i had an idea to try to capitalize the time i spend sitting in front of the tv. i stumbled across some good deals on craigslist/online so i decided that maybe I'd try my hand at restoring/repairing some amps (with a concentration on old solid state) to sell. took almost two weeks around the fourth to drive from Florida to the northeast for a wedding/family time, so i was able to scour Craigslist for great deals (miffed i wasn't able to pickup an acoustic 140 for a hundred bucks in Nashua, NH but that was way further north than i wanted to go)
so this is the first of 3 acoustic 140s I've handled that started my love affair with them. purchased online from a tube amp tech who had recapped it but was at his wit's end because it still didn't work. after bringing it up on a lightbulb limiter (learned my lesson continually replacing power/driver transistors on the kustom!) and nothing sitting to ground. hooked it up and it sounded like tube amp sag times 1000 ie zero attack and the note would ' bloom' in. so i take it apart and he missed a small electrolytic, which i replaced. then i noticed one of the big horkin power resistors had lifted its solder joint from the board. so i fixed that and it worked great!
cosmetically, this thing absolutely Sino when i received it, as if it had spent the past 40 years not in a smoky bar but inside a smoker's lungs. cleaned and febreezed and eventually got the smell out, polished up the chrome bits b and replaced the rusted screws and finish washers with new stainless ones from home depot and it looked almost new
took it to a friend's gig and left with $150 and acoustic 140 #2 (even more of a mess than the first!)...
Post by thetragichero on Jul 20, 2019 12:07:39 GMT -5
acoustic 140 #2 looked like it had been dropped or kicked or something. a couple of pots were broken, still had all of the original filter caps.... no wonder it didn't work!
bent out the front, performed surgery on the pots (for some ungodly reason acoustic used pots with two flat sides, so i had to figure out how to attach the shaft of the broken pots to a working pot, and then attach resistors to the outer lugs to achieve the 50k pot the schematic called for... with some patience and some bad words i was successful)
these amps must be hard on the 5w resistors on the power board because this is what came pout of 140 #s 2 and 3:
they still worked perfectly well, but far be it from me to leave a burnt out part in there
once again washed and polished and now she's listed on reverb
Post by thetragichero on Jul 20, 2019 12:17:35 GMT -5
acoustic 140 #3 is an odd one...
somebody chopped off one of the preamps (ave the chassis along with it) and made a smaller box for it! they did a pretty good job too. had to sacrifice the knobs for #2 along with the pots, so this one got big mxr-style knobs. replaced the electrolytics. this one actually got the preamp board from #2 (that way I'm keeping the one that's the least stock). ended up replacing all of the preamp transistors to modern jellybeans. sounds great and i dig the uniqueness!
Post by thetragichero on Jul 20, 2019 12:21:20 GMT -5
1972 sunn concert bass. picked this up on montclair, nj. power cord was toast sci i replaced it with an iec socket, replaced the electrolytics. cleaned up the metal bits and tolex (spray foam tire shine works WONDERS on old tolex). this thing friggin HOWLS on the boost setting
Post by thetragichero on Jul 20, 2019 12:30:23 GMT -5
1990s ampeg svt3-pro i picked up in raleigh, nc. tube gain pot was broken and the knob was missing. spent more on shipping than i did on the parts (so i bought a second set for the bin). 5 minute repair and paid an obscenely low price for the unit. this totally cops the 90s punk rock bass tones i chased after as a kid
I've got an acoustic 370 that is now working but still have to finish the cosmetic stuff. will post that once it's completed. bought two broken pedals at a swap meet for $20. repaired the boutique klon clone and put a better buffer in the buffered volume pedal. volume pedal/wah enclosure itself was worth the 20 bucks
Seriously, good work. Nice to see someone get a double-benefit out of his/her TV time. (i.e. input of Officer Training Materials, and a positive cash flow. Only thing better would be hot-and-cold running Bier Garten maidens!)
Keep up the postings!
Rule #1: All Lives Are Final. Make sure that the life you have just been issued is appropriate for your needs, before departing the womb.
Rule #2: In case you don't like the life you have, see Rule #1.
Post by thetragichero on Jul 22, 2019 21:20:23 GMT -5
1973 (by my guess from pot/capacitor date codes) acoustic 370
this thing was a bit of a disaster when i received it. somebody replaced the bass pot but tried to make the smooth round shaft have two flat sides using a grinder so that it would fit the stock knob
guy i bought it from said a tech attempted repair but said that it would be too expensive. said low output. for a capacitor-coupled output, that was my first guess. replaced ALL of the electrolytics (including about a billion 1 and 2uf tantalum coupling capacitors). super low output, attached the line out to another amps input and got nothing but noise.
so the problem was in the preamp. my next thought was to test for any open resistors, but before than i just went through all of the resistors on my meter's continuity setting (not sure why, but i did). one of the resistors tested as shorted. so i took it out and it tested fine. head scratch. tested the solder pads where the resistor belonged and sure enough it was shorted. i guess the tech went over all of the solder joints and basically sorted two legs of a transistor together. little to no output makes sense now! cleaned up that mess and tested 'er out...
MUCH louder output, sounded like a cocked wah with the guitar i was testing with. only the mid tone control and volume worked. took a look at the schematic and saw that it could be one of two transistors, one of which had already been replaced with a metal can 2n2222. i have a glut of bc547, so seeing that it was relatively similar to the 2n2484 the schematic called for (relatively small signal stuff, what isn't similar? pinout worked without any weird contorting). and then it worked! i replaced all of the preamp board transistors just for the halibut. had to replace one of the eq sliders (totally busted) with one i got from an organ.
so the original filter caps in all these 70s amps are HUGE. like coke can huge. modern capacitors are tiny in comparison. so how to secure to the chassis if i can't reuse the mounts? like most things, i look for my answer at the hardware store
conduit straps from the electrical section. works for me!
this thing is so growly and wonderful! i planned to keep just the half 140 but this thing SMOKES with guitar or bass!
just need to find another knob since the chrome part fell off
Post by thetragichero on Sept 26, 2019 2:08:45 GMT -5
responded to a Craigslist ad for two celestion vintage 30s ave what i did not know is that they came inside an amp...
95 trace elliot super tramp twin. previous owner stated there were issues using the footswitch. came with a crate footswitch with leds. turns out the switching circuit in the amp doesn't like leds (or diodes in general, I'm guessing) being placed on the contacts. plugged in the vox two button switch i purchased years ago (because it was the cheapest guitar center had) and switching between channel 1 (clean but can get a little overdrive with the gain up), and channel 2 (no clean only distortion) and boost on channel 2 works as expected other issues i found: hum even with guitar volume off, scratchy mastery volume pot, reverb not working as expected (with either channel volume up. it almost seemed as if there were a hard limiter on the reverb... play staccato note with no reverb until the guitar was silent and then it would splash back a little... weird) tone wise i dog the distortion as long as the treble knob isn't too high. seems to only control fizz lol clean channel i felt was too trebley and too bassy. couldn't use a distortion pedal on the clean channel unless the pedal's tone knob was turned all the way down
okay so time to open er up.... (i actually did it twice to troubleshoot some stuff)
hum turned out to be the big 4700uf filter caps. thankfully the ones i had on hand from my last Ali express order fit perfectly, and that the caps i didn't (several 47uf 63v) weren't causing my hum
clean channel: changed 180pf bright cap (c4) to 1nf to allow more than just the highest of fizzy highs through at lower levels of the gain pot attempted lowering the two caps on the bass pot (c11 and c12) from 22nf to 10nf... ended up killing TOO MUCH bass. settled on 15nf
cleaned all the pots, replaced the master volume pot (somebody had already replaced the stock pot and it was a DISASTER)
reverb took some tinkering. at first i thought it was r68 (mix resistor) being too large so i dropped it from 100k to 22k. not that simple there were two tantalum caps in the send and recovery circuitry. both tested at what they should, but i replaced with electro caps just to rule the tants out. r76 measured 100k so i replaced it with the proper value of 47k r73 measured 1k5 and now I'm guessing that was a revision (brown green red, so not a drifted value). i replaced with the schematic value 3k3 tr17 (j112) measured as a short from drain to source so i replaced with 2sk117bl i had (had to reorient but i made it work). apparently my meter registers 30ohms as a short, so it's possible that i replaced a jfet that wasn't dead. all i know is that now the reverb works as it's supposed to. slight volume increase when the reverb is active but I'm okay with that
replaced the speakers (i always intended the v30s for a 2x12 to match my Hammond amp) with Fisher brand musical instrument speakers from a lowery organ. this is the second pair I've gotten and I've had to replace the foam surrounds on all four. there is absolutely zero information online about musical instrument speakers made by Fisher (i spent a few hours and learned way more about the history of Fisher stereo speakers than i ever cared to know).... these roll off more highs than the v30s and i think a little less flubby bass as well... plus all i got in em is about 20 bucks for the foam surround kit
Post by thetragichero on Oct 9, 2019 21:31:24 GMT -5
moog/gibson lab series l3. overpaid for this one but i wanted it. couple things added to this not working: one leg of an electro cap had come unsoldered - easy fix. one of the 2n3055s had both of the mica insulators so the other's collector was connected directly to ground. the output transistors tested okay but i replaced them anyway tracking down why the output was so low. turned out to be a bad speaker Jack. replaced that. this is an interesting preamp. among two dual op amps (lm358 but i socketed and found tl062 to sound much better). also uses the mosfets from a pair of unbuffered cd4007 chips (usually used for bypass switching in effects) as gain and reverb/tone control recovery stages. neat! and you could tell the pcbs were designed by engineers
unseen in this photo is the top two box joints had popped undone. somebody tried a halfassed repair with wood glue and some small common nails. as a whole-assed kinda guy, i removed the tolex and cleaned up the shoddy repair attempt. glued and clamped
buddy i refinished the sg for in green wants me to make his new orange head match his guitar so i ended up ordering two yards of "British emerald green" tolex. won't need that much so i took a little over two feet of it and recovered it. were this for a customer i would've cut it longways for better seam placement, but that's much too wasteful for this project
cts gets great pr from your average guitarist but i find their post 60s speakers (after Bob Gault left to start eminence) terrible. the mid-to-late 70s stock ceramic 12" was no different. had a 10" pyle speaker from an organ pull that sounded just as great as the jensen c10n i pulled and sold for $$$, but it was 8ohms and this is a 4ohm capable power amp so i paired it with a 6x9 also pulled from an organ in a new baffle board, used some grill cloth i purchased for a 2x12 I've been building
I've learned some stuff i would not do again with the tolex and that's important. I'm still not sure if the 3m spray contact cement is the best adhesive. will have to research more
donated the amp to a little church I've been playing guitar at the Sundays I'm not playing bass at the big church. the Trace Elliot 2x12 i ended up with was way too powerful for such a small space
Post by thetragichero on Jan 11, 2020 8:39:01 GMT -5
95 or 96 Marshall jtm60 (same guts as jcm600) mini stack in a lot of ways i think this was the predecessor to the jcm2000 series, not so much in gain and options but in construction methods. 8000 ribbon cables (which if you put back wrong the amp doesn't amplify, just oscillate.... ask me how i know). questionable board placement (close enough to the tubes to suffer heat damage). same runaway bias issue (that's what you get for trying to get cute with zeners and stuff, Marshall!). underspeced bridge rectifier for the heater tap (which was replaced before this one came to me. board is discolored from when the old one bit the dust). besides gobbling through my stash of old and probably already bad el34s, this one sounds pretty good. i like the independent reverb controls (never been a fan of verb with high gain). parallel fx loop volume, when the loop is jumpered, acts like a fatness control. definitely more ac/dc gain than thrash metal the friggin replacement logo (it's creme instead of white) was a months-long ordeal (originally ordered in October, finally received a week ago) I've had it up on reverb 6 hours and already have 8 watchers so hopefully it moves quickly
received this in a trade for the acoustic 370 head and a hartke 4x10 i needed to get rid of. i didn't do much on this besides touch up a solder joint (the crackling sound when the tremolo was on was due to a coupling capacitor that was making intermittent contact to where it was supposed to) be and give it a good cleaning you can definitely see from some of these old sano amps where fender got the ideas for their wonderful pawnshop excelsior (my personal all is in about its fifth iteration, running 6L6s but next time i get the tickets I'm gonna try to run a NFB wire for more headroom.... anyway) anybody else love jumping the channels on a 4 hole input amp? YUM
Post by thetragichero on Jun 18, 2020 0:31:29 GMT -5
never posted this here but i got this jet city 50w combo a few weeks back. it's basically a soldano super lead overdrive with only a couple of component changes and relay switching. came to me cheap because it would oscillate on the overdrive channel and guy didn't know where to go next. turned out to be a bad filter cap. while in there i also cleaned up some previous work that had been done on the amp: guy mentioned that the heaters had been "raised" which to me means the center tap is connected to somewhere with a greater than 0v potential to possibly prevent noise. what actually was done was cutting the traces for pins 4 5 9 on the first three preamp tubes and connecting wires between them and to preamp tube number 4. a lot of work for little to no benefit in my opinion, especially when it's sloppy and you've got heater wires touching other components.... so got it working but wasn't quite satisfied with the "crunch" channel (seemed a bit too lifeless). messed around with that part of the preamp (taking some inspiration from jmp/jcm800 schematics) and now it's in hot rod Plexi territory. ballsy and bright but not ice pick. then the "overdrive" channel sounded blah in comparison so i tweaked that a bit. it's nice cranked but man that 39k cathode resistor on the cold clipper stage definitely compresses the signal a whole heck of a lot. it sounds nice and saturated and i dig it for heavy rhythm but man that crunch channel screams!
Post by thetragichero on Jul 12, 2020 16:55:17 GMT -5
1971 (was sold as a 1967) sunn sceptre that came to me in bad electrical shape (besides all original power supply caps the receipt/vibrato board was trashed, two conductor mains wiring, death cap, etc), missing the back panel, listed as reverb not working. ended up having no tank so of course it wasn't working come to find out there transistors on the reverb/vibrato board were oriented incorrectly, the dropping resistors on the low voltage supply rail had caught fire because as usual, the zener failed short (don't know if I've run into a old amp with a functional zener diode... be it's almost as if it's not the greatest idea to use them to drop voltage). so i removed any traces that were near the scorch marks (carbon being conductive and all) and rerouted where i needed to. put some newer low noise transistors in the right way. added a new accutronics tank. revert worked but not the vibrato. since my oscillator was oscillating i checked the ldr and that was working. then i noticed that whoever mucked about in here before must've gotten tired of the amp not working and jumpered the two leads together. works fantastic! i like the sound of vibrato (TREMOLO) into reverb! recovered in hiwatt/vox panama tolex, made the back panel out of scrap ply (traced the one from the 200s I'm working on now)
all metal bits scrubbed with chrome polish and a toothbrush (wire brush used where really bad)
so now I've got this 1968 sunn 200s. transformers were covered with rust so i decided to remove the bells and paint them. that's when i came across this
glad my vanity decided to paint those end bells! can you imagine 500v+ from the ot plate supply on the chassis? picked up some grommets to reinstall properly
Post by thetragichero on Aug 15, 2020 14:46:36 GMT -5
1977 sunn concert slave power amp
didn't even bother turning it on when i got it as it was such a mess replaced all electro caps and most of the resistors as they were torched
input wiring was a mess. all of the diodes for the power transistors (biasing diodes?) were facing the wrong way. all of the 1k5 5w resistors were torched so instead of replacing them some genius just tacked on higher value (4k7, etc) 1/2w film resistors over top. couple resistors were replaced... by clipping above the board and soldering to those (lazy). new bourns pot (didn't have 100kA in non-stomp box size so i took 1M with a 150k resistor in parallel... close enough), new switchcraft jacks for line in and out (they're just wired in parallel)
plugged it into my kustom 2x15 cabinets and i think I'm deaf now
will probably end up doubling what i paid for in resale (would love to keep it but my rackmount 500w power amp had much lower resale value so that's what i keeps)
couple resistors were replaced... by clipping above the board and soldering to those (lazy).
Au contraire, mon frere. This is the exact method used by repair persons who've been around the block and down to the river... at least a couple of times. As you well know, removing the PC boards (and anything attached thereto) is time consuming. It is considered a good practice to simply snip the bad part out, and solder the new part to the remaining leg stubs. When you're under the gun to fix at least two items an hour, sometimes more, you don't try to make things look like factory-new... you do your durndest to keep your paycheck coming in.
sumgai (one of those old-fogies who had to do exactly this for a living)
Rule #1: All Lives Are Final. Make sure that the life you have just been issued is appropriate for your needs, before departing the womb.
Rule #2: In case you don't like the life you have, see Rule #1.
Post by thetragichero on Aug 15, 2020 19:22:19 GMT -5
so similar to why i was not a beloved employee when i worked for others doing construction type work. too much of a perfectionist i will admit that it saves from lifting traces (which a number were... some of those connected to where they belonged and some not... no wonder the seller said it didn't work too well)
Post by thetragichero on Aug 18, 2020 11:28:30 GMT -5
was in the car for a total of six hours yesterday to pick up this traynor uba1 from a pawn shop (and to pick up some pedals to repair for a guy from a facebook group) paid $300 because the cord is frayed and pots are scratchy. appears to be original can caps (one mallory 80uf 450v and one 40/40 450v for the first supply node. weird) which i will replace with two jj 100/100 500v cans (will run the plate and screen nodes off of these. will fill up the holes and provide slightly higher capacitance... and higher voltage handling for startup) once those come in I'll replace all electro caps, remove the death cap (and throw a 4.7uf cathode bypass cap on a switch for a gain boost since like a good nut i can't in good conscience leave those switch terminals unused), likely will replace the channel mixing resistors (100k stock) with 270k, throw on some power tube grid resistors (1k5 or a more Marshall 5k6), and swap the 470k phase inverter bias resistors for 1M like pretty much the rest of the world uses. installing a pot for adjustable fixed bias (instead of fender-like non-adjustable) is also likely along with replacing the 470R screen resistors with a more el34-friendly 1k no major changes to coupling/tone stack/etc but bringing this guy to the modern era
Post by thetragichero on Aug 21, 2020 4:55:15 GMT -5
stayed up all night but got this all recapped, proper 3 prong power cord, removed heater center tap and installed an artificial center tap, changed the bias supply to adjustable fixed bias and added a bias sense resistor, changed the shared 10w 470r screen resistor for individual 1k 5w resistors, removed death cap and used the switch for a 4.7uf cathode bypass cap on the second gain stage, replaced 68k power tube grid leak resistors with 220k (wish i had some 150k so i could try 6550s in here), changed phase inverter grid leak resistors from 47k (not a typo) to 1M. according to the schematic this has 15k grid resistors on the power tubes that i may remove. have to fire it up and see... have a feeling I'll need to replace a couple pots (even after cleaning i can hear and feel the wiper scratching across the wafer) but I'll try that after testing
Post by thetragichero on Aug 21, 2020 16:05:25 GMT -5
this traynor is killer! played with bass vi, p90 standard tuned guitar, and active humbucker guitar tuned to c# minor. each had its own character through it. adjustable bias is nice: -36v from the schematic is rather cold 58% (from bias sense resistors so even colder when you subtract cathode current). set right at 70%. nice Marshall-type grunt with the ehx el34 and Chinese preamp tubes of unknown age. plenty of highs, big bottom end need to replace the treble pot and probably the "high frequency expander" pot i wanna keep it lol
Post by thetragichero on Aug 21, 2020 20:22:00 GMT -5
this arrived this week as well
one of those things that left me speechless i plan to return this Gibson/moog lab series l5 to stock (along with replacing the filter caps and getting the compressor section working) also came with an l4 head missing the grill which i will strip, use the tolex for a new back baffle on the l5, and retolex it (along with fixing the compressor and new filter caps)
Post by thetragichero on Sept 3, 2020 2:11:12 GMT -5
sunn concert lead. ebay listing mentioned mains hum was all it was outputting (well, it listed 50mhz hum but i don't think that's what they were hearing) didn't even bother turning it on, replaced all electro caps, removed the wire nuts used in the mains wiring (HATE wire nuts inside of things), replaced a burnt 2w resistor on power board and brought up in lightbulb limiter, first without and then with a dummy load to confirm nothing was shorting (learned that lesson on solid state amps). will test into a cabinet tomorrow
Post by thetragichero on Oct 17, 2020 13:40:38 GMT -5
1979 acoustic 125 combo. actually has the original footswitch which almost never happens with 30+ year old amps, although i had to purchase and install a new jones plug on the cable (after learning what a jones plug is). replaced all electro caps (opted for multilayer ceramic for the 1uf caps because they were actually cheaper and with around 30 of em, they'll never need to be replaced). after replacing the caps and properly tightening everything i lost the buzzing i feared was coming from the voice coils of the square magnet eminence speakers. reverb tank output transducer measured open so i investigated a new reverb tank. this is a really odd small size and the smallest tank that would work was still too large/would've required more modification than I'd want on an amp destined to sell. so i busted open my 90s kustom pa head, ripped out the tank, and made the transducer fit on this tank. not a great sound but gives a bit of ambience. there are so many killer fv-1 based reverb pedals on the market these days that if one really wants lush reverb that's a better option cranked has an ac/dc-like crunch which is nice. works well with drive pedals. love these old acoustics
Post by thetragichero on Oct 25, 2020 23:30:09 GMT -5
1970s traynor yba-1a mark ii. 80-90w from a pair 6ca7. this thing was ALL original. original caps, power cable, even tubes (pair of Mullard? made in great britain 6ca7 asking with 3x Phillips 12ax7... need to find a tube tester because if they happen to test good those alone would be worth what i paid for the whole amp) replaced all electro caps, power cable, removed death cap. had to replace the rectifier diodes because one side failed short, taking out the circuit breaker on the back. replaced the circuit breaker with a standard fuse holder. adjusted the bias circuit so this is now running 6550s (i don't think most modern el34-types would last very long in here!). removed the center tap from the heater winding, wrapped in heat shrink, and installed two 100 ohm resistors as an artificial center tap (my thinking with this: if somehow the heaters shorted, I'd much rather spend pennies on resistors than hundreds replacing this behemoth of a Hammond transformer). since i had a spare switch on the back (formerly the polarity switch) i did what any good nut would do (leave no lug unsoldered!): turned it into a "plexi" switch. now on the bright channel you have the option of a 680nf cathode bypass cap (like a Plexi) or a 33uf cathode bypass cap (technically 33uf + 680nf... same thing. stock value was 125uf but the difference between 33uf and 125uf is non-existent). changed the cathode resistor to 2k7 (like a plexi) from the stock 1k5 added 1k5 5w screen resistors to each power tube (attached directly to the socket pin) rather than 470r 10w shared on the eyelet board
got it biased right at 68%. hopefully tomorrow will tone test. need to find a bulb for the pilot light
Post by thetragichero on Oct 26, 2020 15:07:08 GMT -5
^^^^ did quick test through my kustom 2x15 with my ibanez p bass. jumped channels like you'd do on any four hole Marshall, both channel volumes cranked, all eq knobs at noon. if i got within a foot of the speaker cabinet my arm hairs would vibrate. LOUD great tone. sounds cleaner than the yba-1 i had (makes sense as the b+ node for the preamp is at a higher voltage) haven't tried my active pickup metal tele but i imagine will get more distortion with that
Post by thetragichero on Nov 28, 2020 19:10:51 GMT -5
70s road (later purchased by rickenbacker) 440 bass amp. heavy and LOUD (measured 455w into a 4 ohm resistive load with the test signal from my scope) recapped, sold as non-functioning because it only worked intermittently. tracked that down to a bad lm1458 at the end of the preamp (almost by accident: scope lead touched both the output and power pins of the op amp and it would spring to life) and a bad coupling cap going into the power amp. the inductor for the "boost" pull switch wasn't working and of course no pertinent information on the schematic so i had to find an online rl high pass filter calculator (basically it cuts the lowest bass to give an apparent mid and treble boost). settled on 2H for a corner frequency of 67hz (ideally 1.5H or so would be better for a higher corner frequency but I'm working with organ pull inductors so i used what i had) crazy loud. don't have any 4 ohm cabinets capable of the 800w or so I'd feel comfortable with to crank the thing
Post by thetragichero on Jan 2, 2021 17:31:38 GMT -5
picked up a pair of these the other day, peavey standard series mark iii 260d. any gigging musician with his/her salt should have a fond place in their heart for these bombproof peaveys. cleaned inside and out, replaced electro caps and removed death cap. this thing is LOUD and heavy
Post by thetragichero on Feb 18, 2021 17:15:08 GMT -5
picked up a 2001 fender blues junior for 200 bucks today. owner said it was distorted and one of the power tubes was glowing way brighter than the other. silly me threw two new el84s in there and sure enough one redplated. so i open `er up and one of the power tube grid resistors is missing, meaning there's no negative bias voltage going to the tube. no wonder it was redplating and the sound was distorting, there was "push" but no "pull" on the output section! power supply was recapped and a bias trimmer was installed but some of the other electro caps were not replaced, so i'll get those swapped out and likely turn the unused triode into a cathode follower prior to the tone stack (just as it's a rule here to leave no lug unused, i feel the same way about triodes!) some genius also clipped the earth ground on the power cord so this will get a new power cord
Post by thetragichero on Feb 19, 2021 5:44:43 GMT -5
something was off in the ribbon cable with the power tube grid connection for v4. ran a wire from board to board and it's up and running now, will test for sound before twist tying the transformer leads all tidy again. settle on cathode follower into twin reverb tone stack. lowered first stage cathode bypass cap from 47uf to 22uf like a fender should be (the effect on low end is minimal, i know, especially with a 2nf coupling cap)