Author Topic: Princeton Reverb blowing fuses RESOLVED (Read 18746 times)

makingnoise88 · « **Reply #50 on:** October 27, 2016, 04:57:14 pm »

Take another look at the picture I attached in reply#26.
How did you resolve that wiring error?
(A close up pic would do wonders for our curiosity)
[/quote]

Quote from: makingnoise88 on October 26, 2016, 10:08:37 pm

I added the bias tap, but everything else's is the same. The diagram shows that wire going to the intensity pot for the trem.

I was referring to REPLY#26

Sluckey got you straightened out on the LED resistor value, but how do you have it wired?
You should have created an artificial CT with 2 100ohm resistors (which is why I thought you had 50ohms feeding that LED

)
Sluckey picked up on the values (100K and 68K - because he is forum "establishment")

Did you incorporate an artif. CT and how did you wind up wiring that area in the circle of my posted pic?

Here's an adjusted schematic snip:
[/quote]

Gotcha! Ok so I didn't know I needed an artificial Center Tap. I'll get that installed.
I haven't gotten to cleaning up that spot yet what I'm going to do is use the 180ohm resister that just came in and use heat shrink to make sure its all clean. I'll do that replace the heater wire between the 6v6 and V4 and let you guys know what happens.

makingnoise88 · « **Reply #51 on:** October 27, 2016, 07:30:24 pm »

Alright, I found and fixed the broken wire! I'm getting 6.1 on my preamp tubes now! But I rewired the led with a 180ohm resistor and did the artificial ct and now I have no led at all!
Also no sound. If I turn the reverb pot I can get some hum but that's it.

eleventeen · « **Reply #52 on:** October 27, 2016, 09:20:20 pm »

All tubes lit?

1-2 volts on preamp tube cathodes? (pins 3-8)

Redo your voltage chart from some posts back.

Early preamp tube has not 350 volts on plates...(pins 1, 6) more like 180-200. Not the 12AT7 reverb driver, that will have BIG volts on the plate.

Print out a schematic for PR and any place where you see a voltage reading, check your build against it. There no "V1", "V2" on the Fender schematic and thus there is not a super obvious correlation between what YOU happen to call V1, V2, V3, V4 (probably derived from the physical sequence of those tubes = perfectly logical) and the ACTUAL V1, V2, V3, V4. You have to get those elements straight in your thinking.

You know for sure that the first 12A_7 is almost certainly the first preamp. 180-200 volts on the plates, 1.x volts on the cathodes. You know that whichever tube has its cathodes and grids and plates strapped together and which should get rather HOTTER than the other tubes, with BIG volts on its plate is the reverb driver. Probably V2. You know the little tube closest to the power tubes ought to be half phase inverter and half trem oscillator. Probably V4. That leaves only V3, half is the the reverb recovery, the other half wet.dry mixer.

It is very, very easy to get confused to how the two tubes which are split function, V3, and V4, are allocated. Each 12A_7 tubes has "1-2-3" half and a "6-7-8" half. You must must must get the halves right and coherently right in your thinking. Yes?

sluckey · « **Reply #53 on:** October 28, 2016, 07:19:28 am »

Quote

But I rewired the led with a 180ohm resistor and did the artificial ct and now I have no led at all!

LEDs are fragile. It's possible that it's dead after all that work on it. If it's still alive you probably have a wiring error or poor connection.

Those filament wires really need a secure mounting point such as a terminal strip. Floating around like that is inviting gremlins.

makingnoise88 · « **Reply #54 on:** October 28, 2016, 06:42:30 pm »

I used a new LED so I'm not sure whats wrong. I'll try it again I guess.

Here are my new voltages.

6v6s read the same.
1. 33.1
2. 2.9
3. 395
4. 387
5. -24.9
6. -24.9
7. 2.9
8. 33.1

12ax7 closest to the 6v6 (V1?)

1. 163
2. 00.3
3. 3.2
4. 2.9
5. 2.9
6. 172
7. 5.6
8. 65.9
9. 2.9

12ax7 next in line (V2?)

1. 146.7
2. 00.1
3. 1.4
4. 2.9
5. 2.9
6. 144
7. -33.3
8. 1.5
9. 2.9

12at7 Although I'm using an ax for right now.

1. 389
2. 0.1
3. 6.6
4. 2.9
5. 2.9
6. 389
7. 0
8. 6.1
9. 2.9

12ax7 last in line (V3?)

1. 143
2. 0
3. 1.4
4. 2.9
5. 2.9
6. -141
7. 0
8. 180
9. 2.9

drew · « **Reply #55 on:** October 28, 2016, 07:36:47 pm »

Are you aware that LEDs have a positive terminal and a negative terminal?

eleventeen · « **Reply #56 on:** October 28, 2016, 07:38:05 pm »

Here are some general thoughts.

First, have you posted a schematic of this amp anywhere...or is it supposed to be a conventional AA964 or AA1164 Princeton Reverb?

Second, you show your 6V6 voltages. There are two general ways of biasing these two tubes. "Bias" is a negative voltage applied to pin 5, grid 1, that partially shuts down the tube, chokes it off...otherwise it/they will overcurrent, pass too much current, redplate, and burn up. One way is to have an actual power supply that, in contrast to (almost) all the other voltages in the amp generates a NEGATIVE voltage. The cathodes of the output tubes are connected to ground which is zero volts, and the negative volts produced by the "bias supply" is applied to the first grids in the 6V6 tubes. There may be (usually is but does not have to be) a control which changes the amount of neg volts applied to these grids. The signal produced by the amp, which has been amplified many times over what comes out of your guitar, is ALSO applied to these grids. The warbly TREMOLO signal is ALSO applied to these grids. This is known as (even if there is variable control to change the bias voltage, "fixed" bias. ++

The second way to bias the tubes is to insert a resistor underneath their cathodes, between the joined cathodes and ground. That resistor is usually 150-250 ohms and is usually a power resistor. When current passes through those tubes, a voltage drop occurs across that resistor. This causes the cathodes NOT to sit at zero volts, but to sit at maybe 20-30 volts. This method is known as "cathode" bias.

One way or another MUST be used, or the 6V6 tubes will overheat and burn up.

If you have fixed bias, the separate supply...then the cathodes are going to sit at zero volts and we will see the neg -25 volts on each pin 5, the control grids, the first grids. If you have cathode bias you WON'T have the -25 volts on the control grids, you'll have zero volts or very low (at idle) volts. instead, the CATHODES of the 6V6 sit at POSITIVE 25 volts. It is the RELATIVE voltages we are concerned with. The grids have to be -25 volts NEGATIVE relative to the cathodes. Whether that occurs with real negative volts, negative with respect to ground, OR, by raising the cathodes 25 volts and letting the grids sit at zero, either way is OK. But not both.

Per your voltage chart, you show the 6V6 cathodes sitting at 33 volts (let's call that the 20-30 volts) which can ONLY occur if you have the resistors under the cathodes and the cathodes are NOT connected to ground. But then...you show the -25 volts on your grid 1 = pin 5.

This cannot be. Or I should say, this can not work.

***********
MOST people would label V1 as FARTHEST from the 6V6, the first preamp tube, "first" meaning the first tube your guitar signal passes through. I believe that would be the most common "convention". Using that practice, the 6V6 tubes usually have the highest "V" numbers, though this is not written in stone.
***********
Your voltages seem generally reasonable other than what I said about the 6V6 grids and cathodes EXCEPT FOR your "last in line" which is not going to work with -141 volts on its plate pin 6. I would normally assume that is a typo EXCEPT you also show 180 volts on pin 8 cathode. Those volts are way wrong. You should have 180 (could be anywhere from 160-200) on the plates pins 1 and 6, and 1.x on the cathodes, pins 3 and 8. Where the heck are you even getting NEGATIVE 141 volts?
***********

Once again....is there a schematic for this build you can post?

*******************
So I am pointing out two anomalies in your voltages. Let me add that EITHER ONE of those could prevent the amp from making a peep of a sound. In the case of the odd 6V6 volltages, those tubes have in effect negative (33 + 25) volts = neg 58 volts on their grids which, if it didn't totally shut off the output tubes (render them incapable of passing signal or passing current) would be darn close. Maybe the amp would be 10-15% as loud as it should be it it made any sound at all.

The voltages on the preamp tube would completely foil its operation. It would not pass signal nor collect $200.

makingnoise88 · « **Reply #57 on:** October 28, 2016, 09:00:55 pm »

Thank you! VERY insightful
This was just a hoffman princeton reverb Build so I used his schematics and layout. I tried to post it but Its not letting me.
I do have a bias trem pot but I wasn't sure how to check the bias or what to set it to!

makingnoise88 · « **Reply #58 on:** October 29, 2016, 10:21:13 pm »

I'm attaching the schematics I'm using.
I'm still not quite understanding the biasing because what I see here in this schematic and what eleventeen said aren't connecting in my head haha. I have done exacticly what's in this lay out and schematic! So what did I do wrong and how do I fix it!

eleventeen · « **Reply #59 on:** October 30, 2016, 01:46:34 pm »

Your 6V6 cathodes are held off ground by a mere 1 ohm resistor. This is a "modern" adaption for the sole purpose of making a BETTER bias measurement. What is a "better" bias measurement? It is a measurement of ACTUAL CURRENT through the output tubes. When we look at an original Fender schematic we see a voltage reading on the G1's, the pin 5's of the output tubes. You could set your amp up (meaning, tweak the bias control) such that that voltage was present on the pin 5s of the 6V6s. Now, go get 5 other sets of 6V6. What you would find (assuming you had a way to measure it) is that the CURRENT through the various pairs of 6V6 would vary. Probably not much, but some. Conclusion: We set the bias VOLTS to a level and ASSUME that that average voltage level will, by partially shutting down the 6V6 pair, produce a through-current for any random 6V6 that will have the amp operate OK and not fry the 6V6. The VOLTAGE reading is quite the indirect measurement. We're REALLY interested in the through-current, we actually do not care about the volts. Knowing the through-current allows us to bias the tubes cold; which would make them last longer, or, hot, which would make them sound a bit grittier and wear them out sooner. Or middle, just right. Your choice.

So, by installing those 1 ohm resistors (you should understand that 1 ohm is practically nothing in tubeland, it is closer to a short circuit than anything else. We can use ohm's law E = IR to read the current through the tube MUCH better than surmising something indirectly-indirectly from a goofy G1 reading. With those R's installed, every milliVOLT atop that resistor is a milliAMP through the tube. We're usually looking for 17-25 mils through a 6V6, in that range. If you find an older pair of 6V6GT from WW2, maybe you want to crank the bias colder to reduce current to preserve the tubes. If you have anew pair of JJ's and like a more distorted sound, crank up bias and run the tubes hotter.

I should say that we HATE to measure current directly, because it requires interrupting the circuit (cutting and then reconnecting wires) AND it forces current through our meter. In the old days, this is what destroyed meters.
********
So the real question is, if your 6V6 cathodes are reading 33 volts (not MILLIvolts, but volts) a mere 1200 times what the tubes can handle, and are held off ground by a 1 ohm resistor, to get 33 volts on the cathodes, those tubes would have to be passing 33 amps, which would launch them into low-earth orbit trailing wisps molten metal, glass, and plastic. Ergo, there is no way you can have followed the schematic AND find 33 volts on the cathodes. (the power supply cannot supply 33 amps, not to mention TWICE 33 amps for two tubes, but your tubes would be cooked in near-zero time)
********

Do you see how all three of 1: bias volts, 2: guitar signal, and 3: trem signal all meet up at 6V6 g1?

sluckey · « **Reply #60 on:** October 30, 2016, 01:52:48 pm »

I had just assumed he probably had his meter set to auto-range and he simply overlooked the small mv indication on the display.

makingnoise88 · « **Reply #61 on:** November 01, 2016, 04:33:03 pm »

Elevteen. Thank you for that explanation!
Ok so pin 1 & 8 is 33.1 millivolts but pin 5 & 6 are - 24.9
So I need to figure out where the negative bolts are coming from

sluckey · « **Reply #62 on:** November 01, 2016, 04:49:44 pm »

Quote

So I need to figure out where the negative bolts are coming from

Those are good negative bolts and they are coming from your vias supply.

He was referring to the big negative readings you had on a couple small tubes. I'm pretty sure those are just operator error readings.

makingnoise88 · « **Reply #63 on:** November 01, 2016, 06:04:53 pm »

Slucky, I'll check that!
I'm still not getting any signal from the amp but if I turn the reverb up with out the tank plugged in it starts giving me a hum and if I turn the trem up I can hear the the speed and the intensity working. But no guitar signal at all.

sluckey · « **Reply #64 on:** November 01, 2016, 06:14:38 pm »

This amp is a bit more complicated than the 5F2A you did back in April, but the troubleshooting procedure is the same. Verify that the amp is wired properly. Click the link in my signature line at the bottom of this post for a good procedure to verify the wiring. When it's wired right it will work.

We've already spotted a couple problems and they have been corrected. You just haven't found all of them yet. Keep looking. You'll get there.

makingnoise88 · « **Reply #65 on:** November 01, 2016, 06:21:56 pm »

Slucky,
You sure know how to give a guy some confidence!
I'll go over it again tonight! One question if I have a jumper wire under the board wrong is there a way to test for that? So I don't have to unsolder everything and lift up the board.

sluckey · « **Reply #66 on:** November 01, 2016, 06:31:06 pm »

Yes. Use your ohm meter to check for zero ohms between the two turrets involved. There are only three underboard jumpers on that board. Should take about three minutes to verify. But it will take a lot more time if they ain't right.

makingnoise88 · « **Reply #67 on:** November 01, 2016, 09:04:45 pm »

Jumpers are correct! Praise God!
Now for everything else haha

makingnoise88 · « **Reply #68 on:** November 12, 2016, 08:05:33 pm »

I haven't had time to get back to the amp until today.
I have gone over the amp with a fine tooth comb and and found a wrong connection on v2 where the reverb trans connects. anyway after that was fixed i haven't seen anything out of the ordinary. I do have a very small broken amount of sound coming through the amp with it turned up all the way. if I turn the term up it works and the speed works as well but if I turn the amount up to much there is a loud hum that starts and I will have to turn the amp off to get it to go away.
Ive switched the wires on the jack with no difference. So any direction on where to look would be greatly appreciated here are some updated pictures for reference!

sluckey · « **Reply #69 on:** November 12, 2016, 08:16:33 pm »

Those pics are way too small to be useful.

makingnoise88 · « **Reply #70 on:** November 12, 2016, 10:24:29 pm »

Try these

makingnoise88 · « **Reply #71 on:** November 12, 2016, 10:25:47 pm »

makingnoise88 · « **Reply #72 on:** November 14, 2016, 02:57:13 pm »

Any idea of a starting point?
I'm so lost at this point. Ive gone over and over the schematic and layout but I don't see anything wrong yet I still am not getting sound really at all! any help would be greatly appreciated.

makingnoise88 · « **Reply #73 on:** November 15, 2016, 02:45:24 pm »

Well I seem to have a few broken wires!
I used pre tinned teflon wire and had given me one heck of a headache!
I'm going to pull it all and start over wiring everything in! What is the best wire to use?

pompeiisneaks · « **Reply #74 on:** November 15, 2016, 02:49:18 pm »

That should be fine, the only thing you want to be wary of is not to nick the wire when stripping it, it can create a weak spot and after a few bends/moves it may break. Just try to replace the wires that are broken, or resolder them after stripping if possible. Verify continuity on each lead by touching to the turret and the other side away from the soldered connection to ensure you get a continuity beep. If not somethings still not connecting well. That's another quick easy test to do.

~Phil

makingnoise88 · « **Reply #75 on:** November 23, 2016, 02:52:05 pm »

Well I've rebuilt the entire amp and still no sound haha
I've been over and over it, I know I'm simply missing something!
If anyone sees anything please let me know!
I'm uploading images of the amp and voltages that I've taken.
Thanks for all the help so far! I am detumained to figure this out!
Also I am using a larger output transformer ( deluxe trans ) instead of a normal Princeton output trans. And you may notice a pot that is in line and grounded but not hooked up to anything that will become a mid knob after I get the amp running properly!

makingnoise88 · « **Reply #76 on:** November 23, 2016, 02:53:10 pm »

More pictures

sluckey · « **Reply #77 on:** November 23, 2016, 03:16:01 pm »

Where to start! There are so many bad voltage readings in that chart. That indicates multiple wiring errors. Too many to logically troubleshoot at this time. You must double, triple, quadruple check your wiring and correct those errors. Click on the link in my signature line at the bottom of this reply to get started.

Hoffman's first law... If it were wired correctly, it would work. I don't mean that in a smartass way. But it's true. You have the amp in hand and are in the best position to discover wiring errors. So I repeat, Click on the link in my signature line at the bottom of this reply to get started.

makingnoise88 · « **Reply #78 on:** November 23, 2016, 03:20:19 pm »

You are right!
Ok I'll go over everything again.
I am gunna get this thing right one way or the other haha

Willabe · « **Reply #79 on:** November 23, 2016, 03:23:46 pm »

I know your tired and want to get her up and running BUT take your time, go slow so you don't miss anything.

You might be missing the same mistake(s) over and over again.

It will be worth it in the end when you get her straightened out.

makingnoise88 · « **Reply #80 on:** November 23, 2016, 03:54:44 pm »

Thanks wilabe, that's really encouraging!

eleventeen · « **Reply #81 on:** November 24, 2016, 12:36:11 am »

What Sluckey said. You have a ton of wiring errors.

On your 12A_7's the big volts show up on pins 1 and 6, the plates. With the exception of the 12a_7 closest to the 6V6 tubes, the cathodes (pins 3 & 8) should be 1-2 volts.

On V1 you have this flipped, but OTOH, if you were really feeding 361 volts to pin 3 (a cathode.....in a tube where there can't be more than either 100 or 150 heater-to-cathode volts or the tube will blow up) you should be blowing up that tube right now. As in visible sparks, inside the tube, and this could well have created a situation where the guts of that tubes are now welded into a fuse-blowing short. So do not overlook the notion that you are reading the tube pins wrong. Are all your 9 pin sockets aligned the same, eg; the "keyway" the space between pin 1 & pin 9 are all faced the same way?

There is a way to check wiring that I sometimes use that is different than what has been detailed elsewhere, multiple times on this forum. It is not as procedural nor as comprehensive but it is in some ways more definitive.

I clamp one lead of my ohmmeter onto V1, pin 1. A plate. Power is off, of course, and has been for a few minutes. I now go measure ohms to node "D" of the power supply and I either see 100K ohms or something is wrong. Not maybe, not "could be", I read 100K or something is wrong. I now go measure to pin 6 of that same tube and I either see 200K (the series sum of 2 - 100K resistors) or something is wrong. I now measure to node "C" and I either see 110K (100K plate R plus 10K node C-D resistor which I am assuming is 10K) or something is wrong.

I follow every resistive path that pin 1, V1 goes to, until the path is blocked by a cap (which will not pass DC)

Even all the way back at V1, I should be able to get to (eg; measure a resistive path from) the plates of the PI, by going through plate resistor, node resistor, node resistor, plate resistor.

It is EXCELLENT practice to follow those paths, predict the ohms you should measure, and get that number or not. It will help you understand the topology of the amp.

HotBluePlates · « **Reply #82 on:** November 24, 2016, 09:24:36 am »

Am I seeing things wrong, or does the speaker jack have wires on the wrong lugs? I think I don't see a connection to the sleeve/ground lug...

eleventeen · « **Reply #83 on:** November 24, 2016, 04:16:56 pm »

Kind of looks like it, huh?

sluckey · « **Reply #84 on:** November 24, 2016, 05:42:55 pm »

I think I see a jumper between the sleeve and switch lugs.

makingnoise88 · « **Reply #85 on:** November 25, 2016, 05:14:04 pm »

output put jack is wired as follows.
Green wire from OT to the Tip, Black wire from OT goes to Ground and Sleeve then the feed back loop is connected to the Tip as well.

I did find a couple of things wrong with the amp. some wires hidden under the board and a couple of hookup wires in the wrong spot. now that its all fixed I'm still not getting any sound.
So i decided to feel around with a chop stick and see what I can come up with.
Everything is dead quite until I hit the hook up wire from pin 1 and 8 the cathode of the 6v6 closest to the rectifier tube, that is hooked up to a 1ohm resister on the board.
It was scratchy and the amp started making a weird oscillating sound. I removed and replaced the wire with a new one and its still making the same noise. Any idea on what to look for?

makingnoise88 · « **Reply #86 on:** December 01, 2016, 09:49:12 pm »

I'm back to tinkering around with this a little more.
After some more research I'm thinking it my possibly my filter cap.
The amp is motor boating along with a 60 cycle hum!
I know this is rare in tube amps but when I built the amp the first time I had one of the 220v lines going to ground ( YIKES )
So i don't know if I could have possibly messed it up.
Anyway what is the best way to test this?
ground to the chassis and then test each lead?

eleventeen · « **Reply #87 on:** December 01, 2016, 11:56:17 pm »

"Motorboating" is a single, specific thing with a single specific cause: The NFB taken from the speaker is the wrong phase and is POSITIVE feedback, a characteristic of an oscillator. There are 2 or 3 solutions, all of which accomplish the same thing. The usual thing done is to flip the blue and brown wires from the output transformer from where they go now to the opposite tube.

Thus, when we build an amp, we do not cut those leads to length and tuck them in neatly; we leave them long in case they have to be flipped; because this is one of those things that is unpredictable.

At the Fender factory, this WAS predictable, because they built a load of identical amps using a pile of trannies from one supplier. ALL those trannies used the blue for the winding start and brown for the end (or vice versa) and so could simply be color coded, blue to this 6V6 and brown to the other, and be counted on to be properly phased.

sluckey · « **Reply #88 on:** December 02, 2016, 06:56:13 am »

First thing to come to my mind when I hear "motorboating" is filter caps.

makingnoise88 · « **Reply #89 on:** December 02, 2016, 07:03:26 am »

Quote from: sluckey on December 02, 2016, 06:56:13 am

First thing to come to my mind when I hear "motorboating" is filter caps.

What's the best was to test this? Ground to chassis and then test each lead?
I would still be testing in DC correct?

sluckey · « **Reply #90 on:** December 02, 2016, 07:25:01 am »

Use a spare filter cap (20�F to 40�F) and clip leads to bridge the filter caps one at a time. One clip lead to chassis. The other to the positive terminal (or lead) of the suspect cap. No need to disconnect the suspect cap for this test. If you find that the motor boating goes away and/or the hum gets less, change that cap.

makingnoise88 · « **Reply #91 on:** December 08, 2016, 09:55:18 pm »

Back to this again

I decided to pull everything out and start from scratch AGAIN!
Did that built a very clean looking amp went over everything two and 3 times and I have a nearly audible sound if its cranked all the way! I can tell the term works because you can slightly hear that as well.
Here are my voltage readings with a few notes on them as well.
I'll attach a few pictures as well.

http://el34world.com/charts/valve/ValveData.php?e=view&f=19915

makingnoise88 · « **Reply #92 on:** December 08, 2016, 10:09:45 pm »

Pictures there is a mid knob in line but not hooked up!

makingnoise88 · « **Reply #93 on:** December 08, 2016, 10:11:17 pm »

More pics.

makingnoise88 · « **Reply #94 on:** December 08, 2016, 10:12:24 pm »

I'm starting to think that it could be the OT?
Is there a way to test that hooked up?

sluckey · « **Reply #95 on:** December 08, 2016, 10:56:15 pm »

Which voltmeter do you have? Brand and model?

makingnoise88 · « **Reply #96 on:** December 08, 2016, 11:19:38 pm »

GE digital multimeter
GE252A

sluckey · « **Reply #97 on:** December 08, 2016, 11:36:20 pm »

Never heard of it. Even Google can't find any info. Can you post a pic of that rare bird?

makingnoise88 · « **Reply #98 on:** December 08, 2016, 11:43:23 pm »

Sure thing!

PRR · « **Reply #99 on:** December 09, 2016, 12:26:08 am »

> GE252A

GE2524 --- dammit, numbers matter.

Home-store low-price 3-1/2 digit meter.

Manual, note it displays bad, this is pre-press pre-trim image.

Key specs attached.

Welcome To the Hoffman Amplifiers Forum September 07, 2025, 04:13:41 pm

Welcome, Guest. Please login or register. -User Name -Password
Home Help Search Login Register
Hoffman Amplifiers Tube Amplifier Forum » Amp Stuff » Tube Amp Building - Tweaks - Repairs » Princeton Reverb blowing fuses RESOLVED

Choose a link from the Hoffman Amplifiers parts catalog
Mobile Device Catalog Link	Yard Sale Discontinued	Misc. Hardware
What's New	Board Building Parts	Amp trim Handles
Lamps Diodes	Hoffman Turret Boards	Channel Switching
Resistors	Fender Eyelet Boards	Screws/Nuts Washers
Jacks/Plugs Connectors	Misc Eyelet Boards	Tools
Capacitors	Custom Boards	Tubes Valves
Pots Knobs	Fuses/Cords	Chassis
Tube Sockets	Switches	Wire Cable

Welcome To the Hoffman Amplifiers Forum

Author Topic: Princeton Reverb blowing fuses RESOLVED (Read 18746 times)