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Post subject: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 3:57 am
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Hello

we had a little accident this morning.

I was trying to check the bias on my Super Sonic 22. (This is a great sounding amp but what a piece of sh*t from a quality/design point of view - hissy as hell, feedbacking reverb, rattling tubes...)

The bias test points (D35 and D36) where giving me nothing. I discovered that pin 1 on the 6V6s would give me a negative reading similar to what I would expect from the test points. Both were at -33mV.

I let my wife (don't ask me why) hold the multimeter probe and she slipped and touched another of the tube's pins and whoooops...green lights, crackling and burning smell and no more amp.

I pulled the fuse out the back and it looks ok. There is a big white fuse on the board.

What have I done?

I don't trust the local amp tech (we paid lots of money for him to 'fix' a Hot Rod Deluxe and it's never been right...) and anyway, he charges 60 GBP to even LOOK at an amp!

Please help...


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 5:18 am
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I can't help but suggest you post on the tdpri forum as well (you might some people awake there).

I got a new SS22 this week. My wife said "but it's the same as the green one. And the black one and the little black one." She was referring to the Selmer, Super 60 and Vibrochamp of course. My mouth opened but the words didn't come out...

Good luck


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 6:44 am
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lockie wrote:
...The bias test points (D35 and D36) where giving me nothing. I discovered that pin 1 on the 6V6s would give me a negative reading similar to what I would expect from the test points. Both were at -33mV...


Hi lockie,

Do you really know what you are doing? Not trying to be mean or anything, but pin 1 of a 6V6 is not used for the tube itself, just a connection point for another part of the circuit, but the 6V6 doesn't use it so it is pointless to try and measure anything there. :?: You might have been on the wrong side of the diodes when trying to check the bias, as one side of the diodes will give you no reading (striped end), while the other side will give a mV reading. There is no "-33 mV" reading anywhere in the amp unless your meter is hooked up backwards. The bias voltage to pin 5 of the 6V6 would be a - DCV (approx - 44 VDC), not mV, and the bias voltage at the test points are not - either, but a + mV (approx 24 mV DC).

One of the internal fuses could be blown, F2, F3 and F4 are all in the power supply section. I suspect that F2 (time-delay 10 amp) for the filament supply, or F3 (fast-acting 1 amp) for the bias supply, or not likely but possibly even F4 (fast-acting 1 amp) for the +/- 16 volt supplies, could be blown. I hope that it is just a fuse. :!:

lockie wrote:
...I pulled the fuse out the back and it looks ok...


Looks don't always count, check fuses for continuity with a meter. :wink:

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 8:19 am
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+1 shimmilou.

The striped end of the two diodes (the cathode end) is at ground potential so if a measurement is attempted there, the reading will be zero. Depending on which pins were shorted, one of the 6V6s may have been damaged, necessitating replacement of both tubes. If there are any black scorch marks on the PCB between pins or other contact points, they will need to be cleaned off as the carbon trace is mildly conductive (like a resistor). Any work on the amp should only be done after the power supply caps have been drained and verified to be as close to zero as possible to avoid dangerous shocks.

Somehow I have my doubts that the OP should be mucking around with the inside of a live tube amp (the wife should be locked out of the room where the amp is sitting). However, if the OP is insistant on maintaining the amp on his own, he should buy a good bias probe like this one

http://www.amp-head.com/product_info.ph ... ucts_id=70

and read this before sticking his hands back inside a live (or even a powered down and unplugged) amp

http://www.aikenamps.com/SafetyTips.html

PS: We don't need the TDPRI's help. :roll:

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 8:44 am
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Thanks so much guys.

I tried both ends of the diodes and no reading. It must be my meter then. I will go back and check the settings on it.

There were no traces of burn on any of the circuit board - everything looks pristine (and very neatly constructed may I add).

The amp is now with a local repair man (not the guy previously mentioned). He said it sounded pretty serious, but should have it turned around in a few days (he had a load of amps queued up for repair!).

I will ask him for a little tutorial on what I did wrong... Whatever it costs, doesn't really matter - at least the amp was fried and not me or my wife!

Can you suggest anything about the...

• hissing - all the time

• dodgy reverb - the reverb tank resonates to the idling sound of the amp

• tube rattle - this is actually the worst problem, because it's the one thing that seems to project loud enough to be heard in my band!

What a shame Fender didn't spend a little more time making sure these amps were going to be ready for pro use, rather than rolling them out cheaply. I feel like a bit of a mug now for buying one second hand. At least if I'd bought new I wouldn't have walked out the shop with it unless it was perfect (especially for 1K!).

I imagine that eventually people will find fixes for all the above problems, but as the circuit's fairly new, we're in unknown territory...


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 8:58 am
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lockie wrote:
Can you suggest anything about the...

• hissing - all the time

• dodgy reverb - the reverb tank resonates to the idling sound of the amp

• tube rattle - this is actually the worst problem, because it's the one thing that seems to project loud enough to be heard in my band!

What a shame Fender didn't spend a little more time making sure these amps were going to be ready for pro use, rather than rolling them out cheaply. I feel like a bit of a mug now for buying one second hand. At least if I'd bought new I wouldn't have walked out the shop with it unless it was perfect (especially for 1K!).

I imagine that eventually people will find fixes for all the above problems, but as the circuit's fairly new, we're in unknown territory...


Do a search in this forum. There are multiple threads on each and every one of these topics.

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 11:57 am
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Thanks.

It's now fixed! Great local amp tech - recommended by our local shop Remade Guitars.

He replaced both the fuses, a microphonic tube, and the reverb connector which was broken, and biased it properly as well as doing a PAT test. He said he went through 6 tubes to find a quiet one.

All that on a Sunday as well - what a ledge.

The amp is now less hissy, and really sounds good, with one exception - rattley noises. Unfortunately he couldn't hear them in his workshop because his garage door was vibrating like a rattlesnake!

Thanks for the advice - really appreciate it.


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 3:40 pm
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Result!!!
That gives my local shop something to live up to when I return my new SS22 tomorrow!


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Sun Feb 03, 2013 4:21 pm
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lockie wrote:
Hello

we had a little accident this morning.

I was trying to check the bias on my Super Sonic 22. (This is a great sounding amp but what a piece of sh*t from a quality/design point of view - hissy as hell, feedbacking reverb, rattling tubes...)

The bias test points (D35 and D36) where giving me nothing. I discovered that pin 1 on the 6V6s would give me a negative reading similar to what I would expect from the test points. Both were at -33mV.

I let my wife (don't ask me why) hold the multimeter probe and she slipped and touched another of the tube's pins and whoooops...green lights, crackling and burning smell and no more amp.

I pulled the fuse out the back and it looks ok. There is a big white fuse on the board.

What have I done?

I don't trust the local amp tech (we paid lots of money for him to 'fix' a Hot Rod Deluxe and it's never been right...) and anyway, he charges 60 GBP to even LOOK at an amp!

Please help...


I installed two loops of copper (stiff copper wire) loops at the bias test points and a made a nice loop at the main ground..to make it easier to bias..doing a balance circuit next...

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Mon Feb 18, 2013 11:54 am
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:oops:
Also regrading fuses...the +/- 15Vdc power supply has two MINI (micro) fuses (try finding one in a hurry that are soldered of all places between the input power spade lugs) they are labeled F-4 and F-3 on the schematic (and one supplies juice to the bias doubler and filter) i blew one while poking around :shock: and needed it up so i installed to interior chassis mount open fuse holders and installed 1a fast blow types which can be found in a hurry)...

On the PCBA image (the last image on the 22's link) shows them at the upper leftmost corner of the image...just warning you if you are gigging..or on the road gigging...

FYI anybody- here are the guts of a supersonic 22 (tried the TLE2072 swap out for the 072's..they were fine and sounded good no effects in the loop or a few in the loop waiting for the OPA2134's to try..taking measurements...noise, square wave..dist..etc for all chips will post once the 2134's arrive- the loop and switching chips are on the upper left part of the board i removed from the chassis, i tightened ALL spade connectors and applied Deoxit D 5% then 100% on the connections ...all...still have not put the grounds all on a post BOLTED to the chassis -stay tuned -sounds good now..can't wait to try the opa's

BTW- the pilot light runs off of the dc supply....good quick trouble shooting trick..and remember the bias is fed by one fuse also...

http://i1059.photobucket.com/albums/t42 ... 44d0b7.jpg

:mrgreen:

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Thu Aug 08, 2013 1:41 pm
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"...and remember the bias is fed by one fuse also..."

What happens when the fuse goes?...


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Wed Aug 14, 2013 6:29 am
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Interesting...all of this. I put the question to Brad on his Facebook page regarding the reliability of this amp, considering all the issues I've been reading about it since its release. He appears to have two, both of which he gigs with, and has nothing but good things to say about its reliability. :?

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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Wed Aug 14, 2013 7:17 am
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"...and remember the bias is fed by one fuse also..."

What happens when the fuse goes?...


I couldn't believe this, when I first read it. It's because Fender decided to tap the bias power from the same source as the PS for the IC-chips. And the fuse in question lies before the junction.

No bias power = blown output tubes and perhaps more damage --- in most tube amps.


http://support.fender.com/schematics/gu ... ematic.pdf


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Post subject: Re: HELP - Supersonic 22 DISASTER!
Posted: Wed Aug 14, 2013 3:43 pm
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:shock:

I would consider replacing F4 with a jumper wire and taking my chances. :idea:

I wonder what good reason you would want a fuse in the bias supply? :?

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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