Help with Juicy Blueberry Xtreme preamp blowing fuses...

BassKulcha

BassKulcha

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"I swear it was working when I put it away..."

It's true! And it was freaking glorious. However, after being stored away for a few years, it has decided to blow a fuse every time I turn it on. I thought it might be the rectifier, so I swapped it out with a new one, but it still blew a fuse.

There appear to be no issues with the resistors or capacitors (visually), and all the traces and soldering look good.

The RCA jacks are attached directly to the circuit board, and I know that has caused some issues, but these all look fine.

I'm a little stumped on how to troubleshoot this. Does anyone have thoughts or direct experience with the Blueberry?

This is a very well-regarded and amazing-sounding preamp, I'd really like to get this working again...
 
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Juicy Music Blueberry Preamp - Tech Info?

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 opened it up to put tubes in and see that 2 traces to the rectifier bridge are lifting. The PCB looks like it took...
www.diyaudio.com www.diyaudio.com
 
Hi BK:

You may also want to check the Klipsch forum site. Mark Deneen, designer and former owner, of JM preamps has a post on these preamps. I just checked the post and he was active (on that post) back in November 2025. These are definitely great preamps. Worth keeping in good working order. Good luck and keep us posted on your repair progress.

Also, you want to ask a moderator to move this post to the Tube category. You may get more traction to your issues.

 
BNR_1 said:
Hi BK:

You may also want to check the Klipsch forum site. Mark Deneen, designer and former owner, of JM preamps has a post on these preamps. I just checked the post and he was active (on that post) back in November 2025. These are definitely great preamps. Worth keeping in good working order. Good luck and keep us posted on your repair progress.

Also, you want to ask a moderator to move this post to the Tube category. You may get more traction to your issues.

Click to expand...
Thanks, I've looked there and checked whether there's been a similar issue, but haven't found one. I'll post to see if MD or someone who's experienced this problem responds—
 
Well, I think I figured it out! Five hours of diagnostics and head scratching, with some desoldering thrown in.

I tested all the power supply caps for shorts, then tested them and the heater supply filter capacitors with an ESR meter (all in excellent health), then tested the BR101 bridge rectifier with the DMM and found out that one leg was shorted. To verify, I desoldered the bridge rectifier and removed it from the PCB, retested it and, yup, that was it! The issue is that a 10W resistor right next to it creates excessive heat…

I just ordered an upgraded BR102 bridge rectifier from Mouser and will solder it in (with about 3/4” of airspace underneath) when it arrives.

While I still have to wait to see if this is the fix, it seems more than likely. I love it when you can figure something out and fix it yourself...
 
BNR_1 said:
Hi BK:

You may also want to check the Klipsch forum site. Mark Deneen, designer and former owner, of JM preamps has a post on these preamps. I just checked the post and he was active (on that post) back in November 2025. These are definitely great preamps. Worth keeping in good working order. Good luck and keep us posted on your repair progress.

Also, you want to ask a moderator to move this post to the Tube category. You may get more traction to your issues.

Click to expand...
Mark Deneen here. Send me a PM and I'll give you my email.

It us about 100 percent certainty that the low voltage rectifier has failed. It's an easy fix if you can solder and trim a few wires.

It's the #1 failure on Blueberrys of all models.

I'll be able to give you the details by email.

Once fixed, you will have good results and all will be good. There's also the chance it could be simply a LOOSE regulator. Just to be sure, try the following:

Using meter when unit is on, check voltage on top of the TO-3 regulator found inside the 2" x 2" black heat sink. It must be 5.7-6.5 VDC. If it is not, check to see if the mounting screws have loosened. Tighten, but not more than necessary to have firmness. Over tightening can crack the PCB.

Send me aPM.

Mark

Edit: I should have kept reading the thread!! Ha!

You need more info about this. Don't mount the new bridge on the PCB. I have s better long term fix.
 
Wow the designer himself responding to his product sold decades ago. That is amazing. Probably don't want to remount the bridge to the PCB, and get it on the chassis for improved heat transfer. Looking foward to read about your successful repairs and returning the unit back into service.
 
DesertRatt said:
Mark Deneen here. Send me a PM and I'll give you my email.

It us about 100 percent certainty that the low voltage rectifier has failed. It's an easy fix if you can solder and trim a few wires.

It's the #1 failure on Blueberrys of all models.

I'll be able to give you the details by email.

Once fixed, you will have good results and all will be good. There's also the chance it could be simply a LOOSE regulator. Just to be sure, try the following:

Using meter when unit is on, check voltage on top of the TO-3 regulator found inside the 2" x 2" black heat sink. It must be 5.7-6.5 VDC. If it is not, check to see if the mounting screws have loosened. Tighten, but not more than necessary to have firmness. Over tightening can crack the PCB.

Send me aPM.

Mark

Edit: I should have kept reading the thread!! Ha!

You need more info about this. Don't mount the new bridge on the PCB. I have s better long term fix.
Click to expand...

Hi Mark, I sent you a DM. Thanks!
 
BNR_1 said:
Wow the designer himself responding to his product sold decades ago. That is amazing. Probably don't want to remount the bridge to the PCB, and get it on the chassis for improved heat transfer. Looking foward to read about your successful repairs and returning the unit back into service.
Click to expand...

I try to help whenever I know of an issue. I can't take in units for repair, i have no shop, but I can at least advise.

I'm still supporting PARAGON AUDIO customers who bought preamps in 1975!
Cheers!
 
DesertRatt said:
I try to help whenever I know of an issue. I can't take in units for repair, i have no shop, but I can at least advise.

I'm still supporting PARAGON AUDIO customers who bought preamps in 1975!
Cheers!
Click to expand...
Thanks Mark for your support. There are many businesses still in operations today that would provide less support for their products than you have done so.
 
BNR_1 said:
Thanks Mark for your support. There are many businesses still in operations today that would provide less support for their products than you have done so.
Click to expand...

I'm just an audiophile, like my customers. I made many mistakes - like under-specifying that bridge - and I would feel terrible not doing what I can do to help.

Be sure to let me know if you have more Q's.
Cheers,
Mark
 
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