Got in the correct pots for OD volume, Normal volume, and Bass - which are A1M (misordered and got A1K previously). So . . . . after installing all the correct pots, as well as changing the 2 caps and 2 resistors (C21, C37, R41, R42), I fired it up. Normal channel works PERFECTLY. Gain, all EQs, Presence, Volume, Depth, all great. However, when I switch to the Overdrive channel, the Overdrive gain control does nothing. The Normal gain control seems to control a small amount of gain but comes through the speakers like a clean channel - is the Normal gain control supposed to act on both channels?
Seems now that the Overdrive gain pot could be bad, even though I just put in a brand new Alpha today
I'm about to give up on this damn thing.
on the jca50 and 100 the crunch drive also effects the lead channel. on both amps the crunch and lead channel are mixed together right before the cathode follower. so the lead channel is actually both channels running at the same time. this is not true for the 20 or 22. although the gain for the crunch may effect the lead gain, i know that the two channels do not mix together like in the 50 and 100
Makes sense. So I guess that means the OD gain pot is bad. I had my suspicions when it arrived, and it had the value written in permanent market instead of typed. Oh well, at least they're cheap enough it won't break the bank. I just have to wait a friggin' week and pay $5 to ship it
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you can use a multimeter and check the continuity across the pot. you can see if it is working properly or not. put the meter on one of the ohms settings and check its readings but you should take it out of the circuit before doing this.
Pulled the board out again to remove and check resistance on a couple pots I was suspicious of. Checked out OK. Then when I went to put the Overdrive Gain control pot back in, I realized what caused the pot to not funcion. Stupid, stupid rookie mistake - I didn't clip the leads on the C21 capacitor after I swapped it out. So when I put the chassis back in the shell, it bent the leads and made contact with the leads on other spots on the board.
So I clipped the leads, checked for damage (there was none thankfully), put it all back together, and fired it up.
End result, 100% functionality. YES!!!
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Sterling AX40 x3 PRS SE245, SE Paul's Jet City amps - all of them modded 2204s Bogner XTC 3534 Kemper rack
Whoa - glad to hear it worked out for you and didn't blow anything (or you) up.
Do you use a current limiter when firing up your amp for first time? Easy to build & use - highly recommended, and could have saved yer a$$ if those leads shorted out something serious.
sahlomonic wrote:I don't, but it looks like I'll make a trip to the hardware store soon.
That reminds me of a rare Bogner amp that uses a light bulb in the circuit for a similar reason.
thd uses a light bulb after the output transformer on their univalve. it acts as a noise gate. lights up as you play notes. may be something similar on the bogner?
Could you post a video and show us what's going on with the Normal master control? Maybe if I hear/see it I could tell you if it's working incorrectly or not.
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Sterling AX40 x3 PRS SE245, SE Paul's Jet City amps - all of them modded 2204s Bogner XTC 3534 Kemper rack
I should have guessed right away -- faulty footswitch. I got a new one and each channel is working normally. Phew. Gonna try it with my band next week.
Hey there! I don't know if this is the right place to post this, but I found this forum recently and have spend some time lurking around and trying to read up. I got my hands on a JCA20HV with matching cabinet and I'm really digging it!. Being the typical guitar guy, I can't ever seem to leave well enough alone, so now I'm considering doing some mods to this bad boy. The amp is great, but is considerably cleaner than other Jet City amps I've checked out. I was thinking about trying to get a bit more gain out of it without changing it too much. Any suggestions? Also, I'm thinking about adding a choke. Is there really any benefit of this on a low powered amp? I see that Mercury offers one that is 9 Henry, and the one most recommend is a 3 Henry from Hammond. What's the difference, and why would I want one over the other? Thanks for any input! Chris
I'm in the process of getting my JCA22H retubed. I called a tech about getting JJ EL84s put in and biased. That will happen sometime next week. After that, I'm going to turn my attention to the preamp tubes. A couple of general questions:
It has five preamp tubes. As I understand it: V1 is the primary gain stage for both channels, V2 is a secondary gain stage for the overdrive/SLO channel, V3 is half for a gain stage for both channels while the other half is a cathode follower, V4 is for the effects loop, and V5 is the phase inverter.
I assume the biggest tone differences would come from V1 and V2. Is that accurate? I had all JJs in my old JCA20H and was quite happy with that. JJs are a bit darker which actually works quite well with this relatively bright amp.
Does it really matter what I put in V4? It would seem as long as it's a functioning 12AX7/ECC83 it really wouldn't contribute much to the tone of the amp. Or am I way off on that?
Does a balanced phase inverter really matter? All the tube sales sites seem to think so, but just about everything else I've read indicates it's not worth the upcharge, at least in a guitar amp.
V1 and V2 have tube covers on them. Are they really necessary?
I just got a used JCA22H from Guitar Center online and I'm having some sort of issue with the crunch channel master volume knob. Everything else seems to function fine with the amp, but the crunch master knob doesn't do anything, at all. The channel seems to sound fine while playing, and the preamp control works normally as well as the EQ, but the master knob is just dead. It also sounds like the channel is fairly normal volume wise.
One other issue I noticed is when I bring the amp off standby while on the crunch channel it has about 3-4 seconds of static that slowly tapers off. I haven't had a chance to open it up yet to see if anything looks off, I figured I would see what you guys think first.
Got my 5012C back from warranty repair with a new black power transformer, decided to de-blue the cabinet as well. Had an extra 1x12 baffle from my pine cabinet and discovered it fit right into the Jet City combo but it was a little taller so I cut a new thinner strip for between the grill and controls. Loving it with a WGS ET65 speaker and boosted with a TC Nova Drive, SLO in Vox clothing...
So what's going on with the brand?.. I think I read somewhere Mike Soldano is no longer with Jet City, Also I remember reading in this same board the bigger amps were getting the same post tonestack / pedal friendly loop the 22 has.
Jet City is still up and running. They are mostly, if not exclusively, dealing with Musician's Friend. Yes, Mikey parted with Jet City, but that doesn't mean the company is folding. I remember Doug saying he wanted to work with a bunch of different amp builders/designers. Look at the amps they've offered and who was behind those designs. Guys from Soldano, Cornford, THD, Friedman, etc. Jet City did not have a booth at NAMM this year, I would guess because they are doing well enough with their current product catalog and just simply don't have anything new up their sleeves at this point.
I've had a few talks with Doug recently about the direction of Jet City, and basically (paraphrasing, in my words at least) he is simplifying the brand by dealing with one huge distributor and not a hundred small ones that won't move product like MF would.
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sahlomonic wrote:Jet City is still up and running. They are mostly, if not exclusively, dealing with Musician's Friend. Yes, Mikey parted with Jet City, but that doesn't mean the company is folding. I remember Doug saying he wanted to work with a bunch of different amp builders/designers. Look at the amps they've offered and who was behind those designs. Guys from Soldano, Cornford, THD, Friedman, etc. Jet City did not have a booth at NAMM this year, I would guess because they are doing well enough with their current product catalog and just simply don't have anything new up their sleeves at this point.
I've had a few talks with Doug recently about the direction of Jet City, and basically (paraphrasing, in my words at least) he is simplifying the brand by dealing with one huge distributor and not a hundred small ones that won't move product like MF would.
Even with Soldano gone they're still gonna keep making all the amps he designed?
sahlomonic wrote:Jet City is still up and running. They are mostly, if not exclusively, dealing with Musician's Friend. Yes, Mikey parted with Jet City, but that doesn't mean the company is folding. I remember Doug saying he wanted to work with a bunch of different amp builders/designers. Look at the amps they've offered and who was behind those designs. Guys from Soldano, Cornford, THD, Friedman, etc. Jet City did not have a booth at NAMM this year, I would guess because they are doing well enough with their current product catalog and just simply don't have anything new up their sleeves at this point.
I've had a few talks with Doug recently about the direction of Jet City, and basically (paraphrasing, in my words at least) he is simplifying the brand by dealing with one huge distributor and not a hundred small ones that won't move product like MF would.
Even with Soldano gone they're still gonna keep making all the amps he designed?
He can still get royalty payments.
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Sterling AX40 x3 PRS SE245, SE Paul's Jet City amps - all of them modded 2204s Bogner XTC 3534 Kemper rack
I guess my previous post was not read or taken into consideration... The Zoom G3 does NOT work well in the JCA100H loop (produces nasty clipping), as opposed to that said in the second post of this thread. Please edit!
I was planning on using the G3 in the loop due to the great delays and reverbs it provides, but had to replace it with a Hardwire DL-8 Delay and a Hardwire RV-7 Reverb, both of which work perfect in the loop of the JCA100H
Welp... finally got it squared away for ya - sorry for the delay, but sometimes this pay-less job doesn't get the response some would like
Just spent WAY too much time pouring through 28 pages of this thread, looking for good mods & other info to put up on the references posting at the beginning of the thread (see page 1, post #3). Check it out, and let me know of anything I missed, or anything cool that's out there!
