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#1
Open Discussion / Re: turntable troubleshoot
Last post by djaaz - Today at 08:59:54 AMThanks!
Schematic is joined and here's the link to he service manual:
http://djaaz.free.fr/Hitachi-HT354-tt-sm.pdf
The turntable has strong fluctations of speed (33rpm +/- 2%)
What i did so far:
Clean the mechanical bits, lubricate the spindle ball bearing.
Changed all electrolycs (except the 4,7uf / 160V)
Changed the three sc458 transistors and replaced them with 2sc1518 (saw a youtube videos where it seemed to solve the specific issue)
In the service manual, they indicate that speed should be fixed by turning the trimpot on the board to get 3V on pin 10 of the ICO1. What i have there is a fluctuating voltage that is somewhere around 3V.
My go to move when i don't know what i'm doing is to change everything that could be at fault and i was about to change the rest of the transistors and try to find this obsolete IC but i there might be something smarter to do than to overspend on this old thing.
Aprreciate any help, guys.
Schematic is joined and here's the link to he service manual:
http://djaaz.free.fr/Hitachi-HT354-tt-sm.pdf
The turntable has strong fluctations of speed (33rpm +/- 2%)
What i did so far:
Clean the mechanical bits, lubricate the spindle ball bearing.
Changed all electrolycs (except the 4,7uf / 160V)
Changed the three sc458 transistors and replaced them with 2sc1518 (saw a youtube videos where it seemed to solve the specific issue)
In the service manual, they indicate that speed should be fixed by turning the trimpot on the board to get 3V on pin 10 of the ICO1. What i have there is a fluctuating voltage that is somewhere around 3V.
My go to move when i don't know what i'm doing is to change everything that could be at fault and i was about to change the rest of the transistors and try to find this obsolete IC but i there might be something smarter to do than to overspend on this old thing.
Aprreciate any help, guys.
#2
Open Discussion / Re: turntable troubleshoot
Last post by mauman - Today at 12:41:06 AMSounds like fun! We can't hurt it, and we just might help. Bring it on!
#3
Open Discussion / turntable troubleshoot
Last post by djaaz - September 02, 2025, 10:42:26 PMHi guys,
I've been fighting with a direct drive turntable almost as old as me that is suffering from fluctuating speed and it's been kicking my ass.
It's time that people who actually understand electronics take a look at it.
Any chance you guys want to help me with that?
Before i upload photos and schematic (hitachi ht-356), i thought i'll ask.
I've been fighting with a direct drive turntable almost as old as me that is suffering from fluctuating speed and it's been kicking my ass.
It's time that people who actually understand electronics take a look at it.
Any chance you guys want to help me with that?
Before i upload photos and schematic (hitachi ht-356), i thought i'll ask.
#4
VFE Projects / Re: VFE switching board vs. 3p...
Last post by jimilee - September 01, 2025, 06:56:50 PMYou'll be fine. You will need to put a pull down resistor (1m) across the 1/4" input lugs to tame any switch pop.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
#5
Open Discussion / Re: Help me hone my pedal chai...
Last post by lars - September 01, 2025, 02:25:29 PMQuote from: greysun on September 01, 2025, 12:44:00 PMthe amp was a mojotone kit I built like 12 or 13 years agoI am impressed that you took on a build like that years ago! 12 years ago I would have never touched a tube amp kit, for fear of the same things...fire, electrocution, accidental time travel (I saw that Philadelphia Experiment movie back when I was a kid!)
Post a gut shot here. I'm sure somebody can decipher what's going on and can suggest what modifications will work to give you the tone you're looking for. Once you hone in your base tone, you'll probably be able to get every sound you want with just one distortion and one fuzz. Billy Corgan famously ran an MXR Dist II into a Big Muff for some of those "unobtainable" fuzz sounds on Siamese Dream. The really great part is that if you got an A-B-Y box, you basically would have a three-channel amp that could switch from "standard" to "lead" to "parallel" and give you a lot of options (if you have the typical 4 input setup on a JTM45).
#6
Open Discussion / Re: Help me hone my pedal chai...
Last post by greysun - September 01, 2025, 12:44:00 PMQuote from: lars on August 31, 2025, 01:19:46 PMAnother option to consider is to have the input circuit of your JTM45 modded slightly. If Marshall followed the typical schematic, then V1 shares a huge 250uf cathode capacitor. You could get a lot more options out of the amp by having the two halves of V1 use different values. One could be voiced for a "lead" channel with a much smaller cathode cap (around 1uf). This will greatly tighten up the sound on that channel. The other channel can be "standard" with a 22uf cap.
I don't understand the huge cathode caps that are placed on preamp tubes. It's been proven many times with reputable measurements that you really gain nothing by going over 25uf. Some of the most revered tube amp designers typically never went over 10uf on their bypass caps.
Nice!
I'll look up what's in there - the amp was a mojotone kit I built like 12 or 13 years ago and, out of fear of the voltage running through it once turning it on for the first time, I brought to a tech at my local place (who now runs Carstons amps, I think) and he modded some stuff after I built it to spec, including the KT66s or 77s or whatever and a resistor value for sure - but I forget what else and he obviously went onto bigger and better things so I can't really ask him and expect him to recall or have a record of it. It'll need new tubes soon enough, so perhaps a tech could look into it then...
The dim-bulb test, while successful, and subsequent (and super manly) run across the room for fear of explosion after that first switch-on told me that I was not cut out for amp building or repair, hehe... Though the tech did commend the build as very clean and solid compared to most kit amps that he'd seen come through, so I'll take it!
#7
VFE Projects / VFE switching board vs. 3pdt f...
Last post by greysun - September 01, 2025, 12:32:12 PMApologies if this has been answered, as I did some sleuthing around the internet and this board before posting, but looking at the VFE docs for a distortion 3 and wondering...
I can see the trimmer is used for the LED, but outside of that is there a reason one couldn't use a standard 3pdt for some of the VFE builds? Perhaps some power filtering is in there that I'm not considering...
Someone on the forum recommended a distortion 3, which I have on order now - was maybe going to rehouse it into an older enclosure so space is a consideration, but looking at the docs, it's not a split rail requirement or seemingly anything requiring the switching board explicitly, so thought it worth at least asking...
Appreciation in advance!
thank you!
I can see the trimmer is used for the LED, but outside of that is there a reason one couldn't use a standard 3pdt for some of the VFE builds? Perhaps some power filtering is in there that I'm not considering...
Someone on the forum recommended a distortion 3, which I have on order now - was maybe going to rehouse it into an older enclosure so space is a consideration, but looking at the docs, it's not a split rail requirement or seemingly anything requiring the switching board explicitly, so thought it worth at least asking...
Appreciation in advance!
thank you! #8
Open Discussion / Re: Help me hone my pedal chai...
Last post by lars - August 31, 2025, 01:19:46 PMAnother option to consider is to have the input circuit of your JTM45 modded slightly. If Marshall followed the typical schematic, then V1 shares a huge 250uf cathode capacitor. You could get a lot more options out of the amp by having the two halves of V1 use different values. One could be voiced for a "lead" channel with a much smaller cathode cap (around 1uf). This will greatly tighten up the sound on that channel. The other channel can be "standard" with a 22uf cap.
I don't understand the huge cathode caps that are placed on preamp tubes. It's been proven many times with reputable measurements that you really gain nothing by going over 25uf. Some of the most revered tube amp designers typically never went over 10uf on their bypass caps.
I don't understand the huge cathode caps that are placed on preamp tubes. It's been proven many times with reputable measurements that you really gain nothing by going over 25uf. Some of the most revered tube amp designers typically never went over 10uf on their bypass caps.
#9
Open Discussion / Re: Help me hone my pedal chai...
Last post by greysun - August 29, 2025, 07:20:23 PMThanks, everyone! I forgot to turn on notifications for this post, so I'm a little late to my own party, but this is great info!
Solid strategy - it's what I've been doing more or less (starting out clean, then adding as I go, mixing/matching/changing order) but maybe a bit less scientific and more chaos. Will streamline the method for sure...
This might be more where my thinking was at when I made this post - Everyone's ear is so different, but it seems like some of these pedals just don't play nicely together at a scientific level. To give a little salt and pepper for where my knowledge was at, I used the green bean as a subtle overdrive into a RAT not knowing that one could just crank the volume all the way and get a pretty respectable distortion from the green bean (e.g., crank the pedal and the tube screamer will make the tubes... scream! Novel concept! Lol). Somehow I always thought this would be detrimental to the amp to crank pedal volume, and maybe it is, but if that's how some of them are supposed to work - I dunno.
I think the Mauman strategy continues, but would love any information on how something like the above works and affects amps, and if there are other "this type of pedal likes to be first, this one last," sort of info if y'all have it!
This is all true - I'm even running KT66s (or 77s or whichever KTXX fits in there), which have that extra headroom and bottom. Will probably move back to the EL34s at some point when it's time to swap out the set just to see if that might help me out, but I can get GREAT clean sounds from this amp, so I still have some hope here!
Good info about the solid state Marshall, though - I'm definitely not particular about solid state vs. tube - In fact, almost got an Orange solid state combo amp that sounded SO good with any guitar I put through it (I forget the model, of course), but ultimately just stuck with the JTM. I liked enough bands that I saw using one (or a similar clone iteration). I do sometimes wonder if this exercise would have been easier with a JCM800 or the aforementioned Orange combo, but I wanted to try something different, so... Winning? (Or at least learning a lesson, lol.)
Definitely keep trying to find pedal chain setups, and almost always look when I'm at shows. The VFE distortion 3 looks interesting and your description sounds like where I want to land. I think I even have most, if not all, of those parts - even some TQ2-l-5V switches! Having never built a VFE project before, it makes enough sense that it straddles between DIY and mass production - I don't have any enclosures, but could always test out the 3D printed enclosures I keep threatening myself to make, lol. I'll look this up!
Thank you all for your time and thoughts - will definitely keep plugging away and will check out some of the suggestions above. Always appreciate this community's willingness to share their info and experiences! :-)
Quote from: mauman on August 28, 2025, 12:12:18 AMI would suggest two things. First, start with one guitar straight into one amp, and set the knobs in a way that sounds good to you.
Then add one pedal, and work with the settings on the pedal without changing either your guitar or amp. If you can find settings that you like, mark them on the pedal or write them down. If you can't, set the pedal aside and move on.
Put another pedal alone between your guitar and amp. Same process. Find the sweet settings, or set it aside. Continue until you've tried all your pedals, one at a time.
Solid strategy - it's what I've been doing more or less (starting out clean, then adding as I go, mixing/matching/changing order) but maybe a bit less scientific and more chaos. Will streamline the method for sure...
Quote from: jessenator on August 28, 2025, 04:32:51 AMSome fuzz circuits (mostly two and three transistor fuzzes) don't like having anything but first dibs on the guitar, so manage impedance accordingly.
This might be more where my thinking was at when I made this post - Everyone's ear is so different, but it seems like some of these pedals just don't play nicely together at a scientific level. To give a little salt and pepper for where my knowledge was at, I used the green bean as a subtle overdrive into a RAT not knowing that one could just crank the volume all the way and get a pretty respectable distortion from the green bean (e.g., crank the pedal and the tube screamer will make the tubes... scream! Novel concept! Lol). Somehow I always thought this would be detrimental to the amp to crank pedal volume, and maybe it is, but if that's how some of them are supposed to work - I dunno.
I think the Mauman strategy continues, but would love any information on how something like the above works and affects amps, and if there are other "this type of pedal likes to be first, this one last," sort of info if y'all have it!
Quote from: lars on August 29, 2025, 01:28:32 PMQuote from: greysun on August 27, 2025, 10:39:43 PMThey're going into a JTM 45 that is so bass-y,There is the problem. As is well-known, the JTM 45 is basically a Fender Bassman circuit that was originally designed for bass guitar and at a time when guitar pedals pretty much didn't exist.
If you're worried people will get all weird about you using a cheap Marshall...
This is all true - I'm even running KT66s (or 77s or whichever KTXX fits in there), which have that extra headroom and bottom. Will probably move back to the EL34s at some point when it's time to swap out the set just to see if that might help me out, but I can get GREAT clean sounds from this amp, so I still have some hope here!
Good info about the solid state Marshall, though - I'm definitely not particular about solid state vs. tube - In fact, almost got an Orange solid state combo amp that sounded SO good with any guitar I put through it (I forget the model, of course), but ultimately just stuck with the JTM. I liked enough bands that I saw using one (or a similar clone iteration). I do sometimes wonder if this exercise would have been easier with a JCM800 or the aforementioned Orange combo, but I wanted to try something different, so... Winning? (Or at least learning a lesson, lol.)
Quote from: Bret608 on August 29, 2025, 01:38:19 PMhonestly back in the day I would just look at pedal setups of bands I liked when I went to their shows, then I'd try it with my gear to see if their approaches worked with my amp, guitar, etc.
The OP mentioned Bob Mould, also a big influence on how I play and sound. I love that sound that straddles the line between OD and fuzz. I would highly recommend building the VFE Distortion 3 available here at MBP. I can get that Distortion + or 250-type sounds, but actually make it work with more different guitars and amps than would otherwise be possible. Bob uses a compressor at the end of his chain to smooth things out, but with the Distortion 3, that is hardly necessary due to the interaction of the fat and filter controls.
Definitely keep trying to find pedal chain setups, and almost always look when I'm at shows. The VFE distortion 3 looks interesting and your description sounds like where I want to land. I think I even have most, if not all, of those parts - even some TQ2-l-5V switches! Having never built a VFE project before, it makes enough sense that it straddles between DIY and mass production - I don't have any enclosures, but could always test out the 3D printed enclosures I keep threatening myself to make, lol. I'll look this up!
Thank you all for your time and thoughts - will definitely keep plugging away and will check out some of the suggestions above. Always appreciate this community's willingness to share their info and experiences! :-)
#10
Open Discussion / Re: Help me hone my pedal chai...
Last post by Bret608 - August 29, 2025, 01:38:19 PMI agree with the approaches mentioned here--honestly back in the day I would just look at pedal setups of bands I liked when I went to their shows, then I'd try it with my gear to see if their approaches worked with my amp, guitar, etc. Swervedriver was the one I probably learned the most from and I still do something like their setup to this day, other than sometimes using my wah at the front of my chain rather than between OD/distortion and the time-based ones.
The OP mentioned Bob Mould, also a big influence on how I play and sound. I love that sound that straddles the line between OD and fuzz. I would highly recommend building the VFE Distortion 3 available here at MBP. I can get that Distortion + or 250-type sounds, but actually make it work with more different guitars and amps than would otherwise be possible. Bob uses a compressor at the end of his chain to smooth things out, but with the Distortion 3, that is hardly necessary due to the interaction of the fat and filter controls.
The OP mentioned Bob Mould, also a big influence on how I play and sound. I love that sound that straddles the line between OD and fuzz. I would highly recommend building the VFE Distortion 3 available here at MBP. I can get that Distortion + or 250-type sounds, but actually make it work with more different guitars and amps than would otherwise be possible. Bob uses a compressor at the end of his chain to smooth things out, but with the Distortion 3, that is hardly necessary due to the interaction of the fat and filter controls.