Orange Rocker 32 // No output to right side speaker (FIXED)

[jacobarber]

If you aren't familiar with this amp, it has 2 separate power amp sections, each going to the respective left & right speaker. 2 output transformers, 2 sets of EL84 tubes, 2 12AT7 phase inverters, etc.

My right output is not getting anything, from what I can tell. Simply putting my hear right up to the grill, I can hear it. Same issue on both natural and dirty channels.

• I've swapped the speaker sides, along with the speaker leads. No change.
• I've confirmed that both speakers are functional.
• I swapped power tubes from side to side. No change.
• I tried new tubes on the right side. No change.
• I tried a new 12AX7 PI tube. No change.
• No tubes are blowing, and the HT fuse is intact.

Now I'm facing the possibility of internal components, as expected. Worst case scenario is that the right side output transformer is faulty for some reason. I've seen one account of an amp tech identify some fire protection capacitor for each output. I  have not yet opened my chassis further than accessing tubes.

Wondering if anyone has experience with these amps in particular or ideas on what to look for. I don't have any testing equipment past a digital multimeter, but if I can identify any faulty smaller components (resistors, caps, etc.) then I am perfectly capable of replacing them. A transformer might be out of my league.

Send me some thoughts on how you'd approach this.

[PRR]

Sounds like a bad connection, bad wire, etc. Bright light and sharp eye (or magnifier).

And why isn't it opened-up yet? What is the first thing a car mechanic does? Open the hood. Can't see anything through steel or wood.

[jacobarber]

Yeah yeah, I knew I'd catch flack for that.

I did end up opening it up after posting. Shined a flashlight all through and couldn't find a single burn mark, loose component, or visibly bad solder joint. That doesn't mean something isn't lurking around in there. Two internal fuses are intact. I worked the send, and 2 return jacks for the FX loop, and made sure all contacts in those jacks have proper connectivity to their end points on the main PCB. Unfortunately there are no schematics floating around, so tracing is sort of guesswork right now.

I'll be taking a closer look this weekend, but with limited equipment I might be in over my head.

[Latole]

Broken contact on output jack or broken solde in the printed circuit.
Check with you finger if output jacks nuts are tight. Do not use tool .
Loose nut = loose jack = may broke printed circuit solder.

Very fun amp to work on 





https://www.facebook.com/watch/?v=469275107336325

[Latole]

More pictures ;  https://forum.orangeamps.com/viewtopic.php?t=55438

[jacobarber]

Broken contact on output jack or broken solde in the printed circuit.
Check with you finger if output jacks nuts are tight. Do not use tool .
Loose nut = loose jack = may broke printed circuit solder.

Very fun amp to work on 

https://www.facebook.com/watch/?v=469275107336325

Thanks for the video link. I actually watched that a good few times before posting this.

No loose jack nuts anywhere.

I went a little deeper with the multimeter and traced just about every point of connection I could find on the rear panel PCB, both with and without plugs in. Everything I can see comes back with solid connectivity, and both left & right speaker outputs are solid back to the main board. Past that, I'll have to remove the main board to see where traces go next.

Since it isn't blowing the right side tubes, I don't think the output transformer is shorting. No solder joints on the rear PCB appear to be broken or loose, but I may just end up reflowing a bunch of joints just to be sure. I do feel like you're correct though, so fresh solder on that rear PCB is likely that next step. Worst case, I have an amp tech who can look at it next week. Hoping to get this resolved myself though.

[Latole]

"  I don't think the output transformer is shorting."
-jacobarber

Winding could be open, not short.

Good luck

[jacobarber]

Winding could be open, not short.

Good luck

Yeah, that too. I'm not discounting a possible bad transformer at all. My knowledge in this realm is more on pedal building, so the whole talk about transformers is new to me.

Probably time to take it to the tech since I don't have any other testing equipment.

[jacobarber]

I think I've found the culprit.

There are 6 larger 5w resistors, 3 around each power tube pair: 2x 5w 1k units on each and 1x 5w 150 ohm unit on each.

Each of these resistors is measuring proper except for the 5w 150 ohm unit on the right channel. I'm going to replace this and see if it solves my problem.

It'll take a few days to get the part so I'll update when its in.

[Latole]

How many ohms you read ?

I see so many guys replacing 3 k resistor because they read 2.9 k.............

[Latole]

The only reliable way to measure a resistance is to disconnect one of its legs.

 Because if other parts are in parallel with it, the reading may be wrong. And worse, it could be another part that will be defective and will mislead you.

[jacobarber]

How many ohms you read ?

I see so many guys replacing 3 k resistor because they read 2.9 k.............

It is swaying wildly between no reading an like 2M ohms. Should be 150 ohms.

I've learned that it is most likely the cathode bias resistor. I'm now recalling the PO mentioned that it sizzled a tube once so he replaced with a matched pair. I suspect that the right side has not really been outputting anything since then and I only noticed because I put my ears up to the speakers like a dope.

I'll remove one leg later and confirm the reading. I checked the left side cathode resistor the same and it measured 150 ohms right away, so I figured the right should do the same.

[thetragichero]

parallel paths would show lower resistance, so it would be safe to assume that that resistor had blown open circuit (OL or 2M or whatever measured)

[Latole]

 I'll remove one leg later and confirm the reading. I checked the left side cathode resistor the same and it measured 150 ohms right away, so I figured the right should do the same.

If you are absolutely sure, then there is no need to unsolder a leg to measure.

A higher reading ( 2 M ohms ) shows that there is nothing parallel to the problem. Your resistor seems to be defective IF you have used your voltmeter correctly; good contact with volt meter probe and resistor leg.

This is the reason for my request to have a figure of the reading

[jacobarber]

While I wait for my pack of resistors to show, I'm wondering about something:

This amp is marketed by Orange as a stereo 30w amp, 15w per side. I feel that is disingenuous. 15w across two separate parallel power amp sections does not mean the amp is cranking 30w the same way a Vox AC30 (or similarly powered amp) does. Wouldn't it be more truthful to say this is a stereo 15w amp? You can't just add the two power sections and call it a day.

I know it can't really be verified without a schematic to see exactly what the two output transformers are doing to the two sets of EL84s. The amp gets loud as hell, even with only one functional output section.

Thoughts?

[Latole]

I have a Fender Princeton Chorus
Fender said is a 50 watts amp ; 2 X 25 watts
Chorus effect need 2 channels

I can't find the Orange schematic

[PRR]

> does not mean the amp is cranking 30w the same way a Vox AC30

Why not? If you feed identical steady tone and identical load to both channels, you DO get 30 Watts. If I hitch two dogs to the plow, I do get two dog-power.

If you don't feed identical signals/loads and don't combine effectively, well, that's your choice. Yeah main to one and reverb to the other may be less than 40W total. All the tubas to Left and all the flutes to Right will rarely sum well.

[jacobarber]

I fixed it. Got my resistors today, swapped the burned one for a new one and buttoned it back up. Came to life right away. Woohoo!

[Latole]

Congrat , you do a good job ?

Question ;

A 5 watt resistor does not become defective for nothing. There must be a reason that must be found and repaired otherwise the new one will suffer the same fate.

If it's an EL84 cathode resistor, there might be a defective tube

[jacobarber]

Well, here's where my stupid comes into play. I only bought this amp a few weeks ago and haven't had the chance to play it much. After posting and going around with the tube swaps, I recalled the PO mentioning that he changed power tubes because one of them fizzled out. I had already thrown in a new pair because I had them and knew they were matched. Everything was lighting up inside and I hadn't messed with a dual power section amp like this before, so the problem went undetected.

The dumb part is that I've realized i had only paid attention to the individual speakers when I put my ear up against the grill. From even 5ft away you can't tell if one isn't working unless volume is really really low. I like playing with at least a little bit of air pushing, so apartment volumes weren't part of the equation.

So I don't think that right side was functional even when I bought the amp. Might be why he sold it for a low price.

I got lucky with this one. It cost me pennies to repair, but could have easily been a few hundred $$ mistake.