Blues Jr, any mods or advice available to convert tube mount pcb to hard wired?

[ctcpete]

I have had issues with the pcb that the tubes mount to on my cream board Blues Jr. I removed the ribbon cables for the pre amp tubes and hard wired the connections some time ago due to having some broken connection points after removing the chassis a few times.

I am now having issues with the power tube connections..power drops out (no sound) or odd noises. Normal operation returns if IU wiggle the power tubes. This has occured on more than one set of power tubes.

I have tried to reflow the pin connection points which seemed to help for a while but the problem has returned.

My question is are there any mod kits available to convert the entire pcb to hard wired? I haven't had it apart in a while and will do so shortly to refresh my memory. I assume it would just involve surface mounting the sockets and running the connections?

Or if anyone has done this and has any advice etc it would be appreciated.

I like this little amp. Have done most of Bill M's mods to it some years ago. My main issue with it is that tube mount pcb.

Thanks

Edit, found info.. evidently Bill at Hoffman Amp has a kit for this:
Hoffman Amplifiers Parts List Page for Amp_BluesJuniorTubeBoard

http://el34world.com/Hoffman/Blues_J...Tube_Board.htm

Looks perfect for me. I may use straight wire for the heater tube connections instead of slicing the ribbon cables into individual wires. Really though if the connections are ok on the main board may be more trouble than it's worth?

Would still love any feed back.

[Enzo]

Having been a Fender warranty station for 29 years, I would say the problem you are experiencing is a bad socket, not a bad circuit board. I have replaced many loose sockets under EL84s in those amps over the years.

[ctcpete]

Having been a Fender warranty station for 29 years, I would say the problem you are experiencing is a bad socket, not a bad circuit board. I have replaced many loose sockets under EL84s in those amps over the years.

Thanks Enzo. I did reflow the solder points of the pin sockets if memory serves. And the re flow around the traces was dicey..didn''t really get a good looking solder point but was afraid to fry the traces. The amp has been on the shelf for a few months after I found and fell in love with an old Traynor Studio Mate. I ordered that kit anyway before your response. Hope it will be a permanent fix.

Also, at one time the amp was left on with no speaker load at a jam..blew some power tubes after that..not sure if that had any bearing on my current issues.

Good to see you here Enzo, hope you're good. You helped me in the past with a few other amps thanks again. I don't get here much. Wish you were closer to NJ so I could bring my stuff to you directly.

[Chuck H]

I don't really have any advice for a better hand wired conversion, but I will say that while I don't ordinarily endorse this sort of thing it may be just right for you. You clearly enjoy tinkering with the amp and the original PCB design isn't very conducive to that. You'll probably enjoy the project and, provided you do an accurate and tidy job, will end up with an amp that can take a lot more bench abuse. In that light I might even suggest the full turret board mod. I don't know if the more extensive conversion accounts for the SS devices in the circuit. I know some didn't once upon a time. Maybe that's been accounted for now. You probably don't want to lose your reverb!? If you like to try mods, change components and plug different tubes in and out often it makes some sense. It is your amp after all. If it can be made to better suit how you'll use it then why stop at a tube socket board? Chassis mount them and put in a turret circuit board. Hopefully you have a spare for the time your BJR would be down.

[g1]

I think Enzo was suggesting replacing the socket, rather than resoldering it. Rebuilding an entire board because of a defective socket seems to be a lot of extra work.
I believe there was a particular type of sockets used in some of this series that was known to be short-lived, but don't recall exactly.

[Chuck H]

I think Enzo was suggesting replacing the socket, rather than resoldering it. Rebuilding an entire board because of a defective socket seems to be a lot of extra work.
I believe there was a particular type of sockets used in some of this series that was known to be short-lived, but don't recall exactly.

ctcpete,

Right! Yes! What Enzo and g1 said. My post was a sort of peripheral observation.

[ctcpete]

Oh well, the kit is ordered. I'll just install it. Seems pretty straight forward ..I know famous last words ha ha. It comes with sockets and everything else I'd need at a reasonable price.

Had a question, in the instructions it calls for slicing the ribbon cables on the tube board side to connect to the socket pins. Would it be worth it to just install straight wire instead? As I said I already installed wire in place of the pre amp ribbon cables after I had a few connections stress and fail from getting flexed. So straight wire instead of this (small pic..click on it):


Regarding the entire main pcb replacement, no way. Way too involved, I could see it taking me a long time and possible pit falls, time is limited as well. The tone is good enough for me now especially with the Bill M mods ( I hear he is feeling better thank goodness) which included a Heyboer output transformer. And yes I like the reverb as is. If I ever went that kind of route and time expenditure I'd rather build a kit of some sort. If I could just get this thing to run reliably I'd be happy.

So thanks again for all the input, I love this forum, I'll update this thread as I go. It can go with my other "amateur muddling through" threads ha ha. I do like to tinker. Was a field tech for many years and it's in my blood. I'm a nurse now and they frown on soldering irons in that environment I swear there will be a guy fixing an MRI machine and I want to grab a screwdriver ha ha.

[Chuck H]

That sliced ribbon cable looks ridiculous to me.

[The Dude]

That sliced ribbon cable looks ridiculous to me.

Yes, and I'm sure it's quite reliable.

I probably wouldn't bother to replace it if it already existed (normal repair). However, if you're starting from scratch with a mod, why wouldn't you use something more reliable and less likely to break when you need to remove the board(s)?

[gui_tarzan]

Ditto. That ribbon cable is too flimsy in my opinion, I would replace it with good wire if I were modifying it at all. I just finished repairing a Jr. and was going to order a BillM. bias kit, but I found that replacing the 27k bias resistor with a 33k (as recommended by several others who did it) made the difference this one needed and now the bias is stable and isn't red-plating one of the tubes.

[ctcpete]

ok straight wire it is..thanks

[Enzo]

It may be moot at this point, but indeed I was suggesting the socket needs to be replaced, not resoldered. If your hand wired kit intends to reuse the old sockets, get new sockets instead.

[ctcpete]

Thanks Enzo, yes it comes with new sockets, all hardware etc.

The mod has an optional step as well I was wondering about..supposedly gets me a "stronger signal push"..not sure what that even means.. (click on picture):

"Tube socket pin wiring diagram
Note that on V2, only 1/2 the tube is used in the stock amp
The ground wire connection on V2 was used to ground out pins 1,2 and 3 to shut it off
You can actually parallel the connections on this tube to get a stronger signal push

To do this, run insulated jumper wires on the back of the tube socket
Pins 1 and 6 get tied together
Pins 2 and 7 get tied together
Pins 3 and 8 get tied together"



Hopefully this thread will helps some other member one day..not much out there on this mod. Thanks again guys.

[Chuck H]

Good call on questioning what "stronger signal push" means. I expect if Fender designers thought it was a good idea they would have done it already. In fact just arbitrarily paralleling a triode onto another without circuit value changes may DECREASE output voltage and lower output impedance in a circuit where the voltage is the more important criteria. Effectively lowering "signal push" as it were. Not to mention the increased risk of crosstalk induced oscillations because of the added grid lead. I may get corrected on some of this but I still don't see an advantage off hand.

[ctcpete]

Well, I have an update. Kind of a good news bad new deal.

A little history, I have been having some issues with the amp after it was left powered on with no load at a jam..a few weeks after that, the power tubes went. Then intermittantly I had odd issues with the power tubes needing to be reseated or just nudged a little. I had tried to retension the tube sockets and reflowed the connection points but finally decided on trying this kit.

I had already installed straight wire for the pre amp tube board connections. Had this thing apart multiple times doing a bunch of Bill M's mods which really mad me love this thing..the tinkering history if that makes sense (time and money spent and I enjoy this stuff) and really, I like the tones especially for home use. I'm an EL 84 guy, love reverb, it has a good speaker and is a good grab and go size. Otherwise, if it were stock, I'd be making it into a speaker cabinet today ha ha. Really if I had to do it again, I'd never buy another pcb board amp..anyway...

So I did the mod,quite a bit of soldering. I started with this:



I unsoldered all the straight wire connections and removed the two remaining power tube ribbon connectors. I installed the heater (filaments maybe?) connections as instructed which resulted in a nice neat run.

I was kind of running out of time and I don't have a nice dedicated work area (airconditioned anyway) where I could just quit for the day so I started rushing some annd had some complications..most my fault and understandable by me.

Anyway I wound up with the amp "working" but very distorted. Sounds almost like a fuzz box..so I'm guessing a pre amp circuit issue, and since all I really did was reconnect new connections etc, probably something I did.

In hindsight, I should have soldered all the tube board connector wires first..I did the opposite. Soldered the wires to the main pcb then soldered to the tube board when it was in place in the chassis under the main pcb which resulted in cramped soldering room. I was getting sloppy too, some too big solder glumps on the socket connectors, and the connectors also have some wiggle to them, several times I could move two adjoining pins where the solder clumps could almost touch..fixed that but obviously not the place for wide solder clumps.

Also I should have used a lower value fine tip soldering iron..was using one with a flat tip.

Also, the previous wire I had when I installed the pre amp straight wire runs (after removing the ribbon connectors) was stranded wire..I'm thinking I would have been better off with solid core..I used some yesterday and it was so much easier.

As mentioned, when I installed the new tube board, the sockets where turned to a different angle so my previousely nice straight runs of pre amp wires to the main pcb board where not so neat now. And I was getting rushed and tired..

So, it has volume, I'd say normal..nice and loud just heavy distortion...fuzz box city.

I'm thinking I may order some solid core wire (20 gauge I think) And will replace all the stranded wire connections and clean up all the socket connections..at least the pre amp connections. Will run slightly longer lengths as well.

The way the instructions (mostly pictures) had me install the sockets, the orientation of the sockets was not like the stock set up and the instructions where good enough but obviousely I had to follow existing connections on the old pcb tube board traces and recreate those on the new one and I had to decipher where my old connections went etc etc.

So, I'm thinking I'm close and just need to clean things up a little (or a lot ha ha).

If I had some solder points on the sockets too close could that result in a distorted signal?? Maybe I need to bend the pins away from each other some..

Thanks again guys, I'll keep updating this...may be a while..will take some after pictures too..was in no mood last night ha ha. These things are a little cumbersome to work on... was also watching my two kids at the time..they took total advantage.. had a damn party upstairs while I stewed at the Kitchen table.