Maybe You Have A Juicy Question?

[the real Duke Spinner]

Just fantastic to see you visiting..

I am still impressed with the  products that I have listened to over the years. 🙂

[rhthatcher]

On 8/20/2022 at 6:42 PM, RealMarkDeneen said:

If so, the RealMarkDeneen might be able to help. I stress MIGHT. I'm getting pretty fricken' old, and before full blown dementia sets in, i might be able to provide help to those JMA owners who couldn't access me after retirement. To all who got stuck, I apologize. 
 

I apologize for not making everything RIGHT. All sorts of mistakes were made, as often happens in life. The only thing I can't do is actual repairs on gear. 
 

I'm not even sure if the company will allow me to be here. I'll find out soon, I imagine. If not, best wishes to all my old friends (and the unfriends too), and keep the hobby alive!

Cheers,

 
RealMarkDeneen

Mark,

 

 

Someone on another forum pointed me to this thread.  I just received a Juicy Music Blueberry Xtreme with Cream preamp recently. I originally owned it from 2007-2018, sold it, and just bought it back. It was "one that got away".  I reached out the the buyer a year or so after selling it, and thankfully he thought of me before listing it again.  

 

I opened it up to put tubes in and see that 2 traces to the rectifier bridge are lifting. The PCB looks like it took a lot of heat in the area of that bridge. The caps around the bridge also look to be cracked / drying out. Before I power it up I want to fix that up.

 

While I'm in there I'd like to implement a few mods you used to do: power supply mod, maxim mods, and 6H30 retrofit. 

 

Is it possible to get a technical package / schematics? 

 

My initial  plan is to simply put a bigger bridge rectifier with a snubber circuit on the chassis and run wires where they need to go. That's an easy fix for the obvious issue, and it solves my short term need.  I'll need more info to jump into the other mods.

 

Best,

Randy

[RealMarkDeneen]

Hi,

I am sure we can get you fixed up, but I'm on s short vacation and only have my phone with me. I'll be back home Friday, and we can pick this up. 
What i see in the photo is a common problem and there is easy enough work around i can help you with. No worries. Send me a PM with your email addy. I'll get in touch in a couple days. 
Cheers,

Mark

[rhthatcher]

5 hours ago, RealMarkDeneen said:

Hi,

I am sure we can get you fixed up, but I'm on s short vacation and only have my phone with me. I'll be back home Friday, and we can pick this up. 
What i see in the photo is a common problem and there is easy enough work around i can help you with. No worries. Send me a PM with your email addy. I'll get in touch in a couple days. 
Cheers,

Mark

 

Mark - I'm a new member on here, so the system says I can't send PM's.   When you're back from your vacation can you try to send me one and we can connect via email?  Enjoy your vacation!!

Randy

[billybob]

1 minute ago, rhthatcher said:

 

Mark - I'm a new member on here, so the system says I can't send PM's.   When you're back from your vacation can you try to send me one and we can connect via email?  Enjoy your vacation!!

Randy

Yes, it will take at least 5 posts by new members to send/ receive messages.

Welcome...

[rhthatcher]

4 hours ago, billybob said:

Yes, it will take at least 5 posts by new members to send/ receive messages.

Welcome...

Great to know - thank you for the tip BillyBob!! 

Couple more to go....

[rhthatcher]

Here's the Blueberry PCB bottom pic below the bridge.   It definitely got hot.

 

 

 

 

[rhthatcher]

Looking at the bottom of the preamps I keep wondering if the thick black wires a heavy duty star grounding method?  

[Travis In Austin]

10 minutes ago, rhthatcher said:

Looking at the bottom of the preamps I keep wondering if the thick black wires a heavy duty star grounding method?  

Welcome to the Forum, you should be pretty close on your posts.

 

Travis

[captainbeefheart]

I typically cut the lift traces off the board and where the last good section of trace is and scrape off the trace insulation and then drill a hole if there is no trace on the other side and install a header pin. If there is a trace on the other side of the board I won't drill a hole and utilize a planar type solder joint on the trace. The header pin can then be quickly connected to wires bringing the circuit out to a chassis mount bridge rectifier. Another option is if the only connection from the power transformer secondary is to the rectifier then just de-solder the wires from the power transformer secondary off the board and run them to a chassis mount bridge rectifier. There are other options also if none of these options are viable.

 

I'd also just ditch those caps around the bridge rectifier, they aren't "snubbers". If you want to dampen any rectifier induced LCR ringing the optimal method is an RC network across the secondary winding. Secondary transformer interwinding capacitance and the rectifier diode junction capacitance are in parallel, adding capacitance across the diode only lowers the resonant frequency. The resistance in the RC network across the secondary is what actually does the "snubbing".

[rhthatcher]

17 hours ago, captainbeefheart said:

I typically cut the lift traces off the board and where the last good section of trace is and scrape off the trace insulation and then drill a hole if there is no trace on the other side and install a header pin. If there is a trace on the other side of the board I won't drill a hole and utilize a planar type solder joint on the trace. The header pin can then be quickly connected to wires bringing the circuit out to a chassis mount bridge rectifier. Another option is if the only connection from the power transformer secondary is to the rectifier then just de-solder the wires from the power transformer secondary off the board and run them to a chassis mount bridge rectifier. There are other options also if none of these options are viable.

 

I'd also just ditch those caps around the bridge rectifier, they aren't "snubbers". If you want to dampen any rectifier induced LCR ringing the optimal method is an RC network across the secondary winding. Secondary transformer interwinding capacitance and the rectifier diode junction capacitance are in parallel, adding capacitance across the diode only lowers the resonant frequency. The resistance in the RC network across the secondary is what actually does the "snubbing".

 

My plan is to ring out the transformer on my Quasimodo tester and oscilloscope, then use a bigger bridge with one of my snubber PCBs on it.  See boards I've made.  The bridge/board will be chassis mounted.  I'll run wires from the transformer on the AC side.  Maybe from solder points on the board, maybe directly I'll snip transformer wires and put quick disconnects on.  I'll make the call as I do it.  DC side will be flying wires soldered to appropriate spots on the board.  I'll cut those fried traces, too.

[captainbeefheart]

10 hours ago, rhthatcher said:

My plan is to ring out the transformer on my Quasimodo tester and oscilloscope, then use a bigger bridge with one of my snubber PCBs on it.  See boards I've made.  The bridge/board will be chassis mounted.  I'll run wires from the transformer on the AC side.  Maybe from solder points on the board, maybe directly I'll snip transformer wires and put quick disconnects on.  I'll make the call as I do it.  DC side will be flying wires soldered to appropriate spots on the board.  I'll cut those fried traces, too.

 

Excellent plan so far, especially since you already have the Quasimodo bell ringer to find the correct RC values.

 

I too would just increase transformer leads to go straight to the boards you have then flying wires back to the board. I didn't know you already had those boards, nice job btw. There have been times where traces were in positions where I could cut out the bad spots and scrape the insulation off, then planar mount discrete components from trace to trace essentially just moving the solder pads from one section of the board to another. This obviously doesn't work for vias.

 

I have zero experience with the equipment you are working on but it appears to me the 3 red wires go to the tube socket for tube rectified B+ and the two blue wires are low voltage AC going to the bridge rectifier for DC filaments?

 

There are better options if you aren't opposed to modifications of the circuit. For the longest possible tube service life you may fit a current source to power the filaments instead of a filtered voltage source. The issue with a voltage source is the cold filament in rush current stressing weak spots in the filament. With a current source it will only output say 150mA, when the filament is at a lower resistance I*R will yield lower potential across the filament, as it warms up and resistance increases the current source will increase voltage across the filament until the heater has stabilized. What's even better is you can set it to a tad under the rated current, say 145mA which should yield around 12.2v instead of 12.6v for even longer tube life. With the price of NOS tubes right now, and the fact they will just go up in price as they become more scarce tube life and protection isn't a bad thing.

 

 

[BNR_1]

Hi Mark:

 

Hope you are enjoying your vacation.  When you get a chance is there an opportunity to obtain a schematic for your Blueberry Extreme.  I have an issue with my preamp.  Regards

[captainbeefheart]

1 hour ago, BNR_1 said:

Hi Mark:

 

Hope you are enjoying your vacation.  When you get a chance is there an opportunity to obtain a schematic for your Blueberry Extreme.  I have an issue with my preamp.  Regards

 

We can help until Mark returns from vacation. Most of the time I don't even print out a schematic when doing repairs/mods unless it's an extremely complex PCB with a lot going on like modern multi-channel home theater integrated amplifiers. In these s instances of course a schematic will certainly speed up the repair time. There are times when no schematic is obtainable and with something like a multi-channel home theater type amp, now the repair  takes longer because I need to beep out traces/connections on the board to draw up my own schematic of the circuit in question.

 

If you post some pics of inside the amp and boards then I can draw up a schematic.

[lighting guy]

17 hours ago, rhthatcher said:

 

My plan is to ring out the transformer on my Quasimodo tester and oscilloscope, then use a bigger bridge with one of my snubber PCBs on it.  See boards I've made.  The bridge/board will be chassis mounted.  I'll run wires from the transformer on the AC side.  Maybe from solder points on the board, maybe directly I'll snip transformer wires and put quick disconnects on.  I'll make the call as I do it.  DC side will be flying wires soldered to appropriate spots on the board.  I'll cut those fried traces, too.

Hey Randy!  You have a PM.

Darrell

[RealMarkDeneen]

15 hours ago, BNR_1 said:

Hi Mark:

 

Hope you are enjoying your vacation.  When you get a chance is there an opportunity to obtain a schematic for your Blueberry Extreme.  I have an issue with my preamp.  Regards

 

Send me a PM with your email addy and I will get you on the BBX document train.

 

Cheers,

Mark

 

[Coytee]

37 minutes ago, RealMarkDeneen said:

Send me a PM with your email addy and I will get you on the BBX document train.

 

Hi Mark,

 

Good to see you back.

 

This is none of my business and people certainly have reasons why they might do or not do something....  (AND, maybe it's been done already?)

 

But I read this and can't help to think that it would simply be a good idea to post the schematics "here" (or somewhere) for posterity.  There may come a day where someone emailing with you won't be easy.... yet your legacy items will still be in circulation.  Having it publicized would allow help for them to continue.

 

Again, I know it's none of my business....and that possibly it's been done.  I just keep circling back to this line of thought so after the 14th circle back, decided to mention it.

 

 

[RealMarkDeneen]

I am back from vacation today Friday the 21st. But on Monday I'll be getting surgery and be out for at least a few days.

 

I'll get some info to Rich today about the power supply. I'll get a few docs ready to mail this weekend, but it will be a little later before I can then address more issues.

Mark

[RealMarkDeneen]

19 minutes ago, Coytee said:

 

Hi Mark,

 

Good to see you back.

 

This is none of my business and people certainly have reasons why they might do or not do something....  (AND, maybe it's been done already?)

 

But I read this and can't help to think that it would simply be a good idea to post the schematics "here" (or somewhere) for posterity.  There may come a day where someone emailing with you won't be easy.... yet your legacy items will still be in circulation.  Having it publicized would allow help for them to continue.

 

Again, I know it's none of my business....and that possibly it's been done.  I just keep circling back to this line of thought so after the 14th circle back, decided to mention it.

 

 

 

I did post the Peach schematic on the K-forum. Possibly it was the for sale section though.

YES, I will post it all here if that's ok with moderators.

 

Thanks, that was my reason for coming back.

Cheers

[RealMarkDeneen]

Peach Schematic - - disclaimer: this is a GENERAL schematic. There were many minor revisions to actual production models, some don't rely 100% on every value of resistor, etc. But any tech should be able to see the design and how it works.