Pignose Hog 20

[highplainsdrifter]

Hi there,

This is my first post here so firstly hello.

I've just scored a used Pignose Hog 20 amp. I got it for $20 but I not sure its not working. It all looks good. I'd say the batteries are toast from lack of use. But I'm not sure of what kind of power adaptor to get it's 12VDC but I don't know the mA rating. And also whether I can run it without the batteries in it. I would like to get it going before I spend $50-60 on 2 new batteries for it.

So I guess my question is, is there anyone on here that has experience with this little amp, a copy of the manual and perhaps a schematic.

cheers
mike

[highplainsdrifter]

So after a few days trolling the net I happened across Jim McBride's www.bottle-o-blues.com

Jim makes the bottle-o-blues harmonica microphone. He all so sells the Pignose Hog 20. Jim helpful told me that the power supply that he has for the pignose is a 12v 1500mA one.

So tommorow I'll go and get one and see if I can get my Pignose going.

Also having had a closer look at it I think it should run without the batteries in it, so thats cool. Its actually a neat little amp the chassis once unscrewed from the cabinet comes out totally leaving the cabinet with only the speaker in it. So it'd be an easy amp to completly replace the amp with something else and just hook up the speaker.

I'd still be greatful for any more info about this amp. A manual or Schematic.

Cheers
mike

[highplainsdrifter]

Wow I'm supprised no one has any info on this amp?

Anyhow I got a 12VDC 1500mA power adapter yesterday and its up and running again. Although theres a slight hum or buzz going on like a bad earth.
It does run without the batteries in there so thats cool. If you haven't seen one of these the way its design is quite cool. They've used connectors for a few things onto the circuit board.
Both the input jacks and the headphone jack have these and can be unconnected from the board.

I've removed both the front and back inputs as they had plastic threads and had both stripped. I'm not sure how these were wired but they both look like stereo inputs (well they have 9 lugs) the back one is wired to the front one and the front one has 2 wires going to the circuit board. Not sure if there is some switching in there or not.
heres how its wired


                 Rear input                                                        Front Input

Anyone know whats going on here?

I've just replaced the front one with a new mono input and it seems to be working okay.

Its actually quite loud. More than enough for our 1 bedroom flat. I could see how cool it would be with the batteries in it.
Its built in distortion leaves a bit to be desired, not to my taste anyhow. But with a overdrive or distortion pedal in front of it, it sounds okay.

[J M Fahey]

Hi Highplains. Well, there´s not info on many popular amps, even less on this excellent yet less sold one. Besides, Pignose usually tries to not give too much details. <Most what´s known about them, comes from curious end users like us. Would you please post some photos of its guts? It would be very interesting. Thanks.

[Carl]

I had a Hog 20. Gave it to my brother and wish I had it back.

It uses 2 six volt 4AH SLA batteries, wired in series. Don't overcharge them.

A very sweet sounding amp. My Korg Pandora PX4 sounded better with the Hog 20 than any other amp.

Carl

[diyfalk]

I know this is an old thread, but I came here by a search-engine looking for the schematics.
Just want to post, if someone else is searching...

Best

[J M Fahey]

Hi diyfalk, thanks a lot for posting.
Many wanted to know it.  :dbtu:

[diyfalk]

I am trying to repair mine.
There where some faults i could fix, but not yet all.

For example, the Switch of the Squeal Pot was broken, thats the reason i build in a new one.
What i didn't know before ordering was, that it should have been an opener switch.
I bought a Closer...  :-(
For the moment that is ok, cause i do not need the distortion.
If someone here has an idea where to get one here in europe let me know.
I can buy one from Pignose directly, but the shippingcosts will be much higher than the pot.

Then another fault was the Input-Connector on the backside.
I build in a normal Connector, cause i do not need the switching.

Then the Tone-Pot had a loos connection. I could fix that by cleaning it.

So now the last thing what i think is broken is the TDA7240.
With headphones the sound is quiet fine, but when i hear over the speaker, it is strange.
If the sound is loud it is free from distortion. If than the guitartone gets quieter the distortion starts.
So normally i would expect that it is the way round but it isn't.
The loudspeaker is ok, i checked it.

So after changing the TDA (maybe this week), i will try new caps.
Hopefully some day it will sound fine again.
I never heard him playing right...

[J M Fahey]

the Switch of the Squeal Pot was broken, thats the reason i build in a new one.
What i didn't know before ordering was, that it should have been an opener switch.
I bought a Closer...

No, you need the "regular" switched pot: on "0" the switch is open, and the clipping diodes are out of the circuit; on "1" and higher the diodes are connected and it starts clipping, raising the Squeal pot it clips more.
That said, that distortion circuit is horrible  , don't waste time on it.

For the moment that is ok, cause i do not need the distortion.
If someone here has an idea where to get one here in europe let me know.
I can buy one from Pignose directly, but the shippingcosts will be much higher than the pot.

You already have the correct pot/switch.

Then another fault was the Input-Connector on the backside.
I build in a normal Connector, cause i do not need the switching.

Post a picture, it is not on the PCB.

Then the Tone-Pot had a loos connection. I could fix that by cleaning it

Maybe. Although you might have to replace it.

So now the last thing what i think is broken is the TDA7240.
With headphones the sound is quiet fine, but when i hear over the speaker, it is strange.
If the sound is loud it is free from distortion. If than the guitartone gets quieter the distortion starts.
So normally i would expect that it is the way round but it isn't.

That does not sound like a broken TDA7240 at all but like a bad speaker.
Connect another speaker to check it.

The loudspeaker is ok, i checked it.

Not so sure, connect the amp to another speaker.

So after changing the TDA (maybe this week), i will try new caps.

What you are doing is called "shotgunning", replacing parts at random trying to find the problem.
Bad news: it does not work that way
You will never ever find a problem that is not caused by "bad parts", such as a bad connection, poor soldering, cracked track, etc.
In fact, I very much suspect the phone connector (labelled "PHNOE" on the schematic) which has an internal leaf switch which may be dirty/worn/weak/rusty/all of the above.
Squirt a little contact cleaner or at least some WD40 into it and plug in/out the proper plug a few times to clean it.
Or momentarily solder a wire across the switch contacts.

Please measure and post voltage on 7240 pins 3/5/6/7 .
Thanks.

[Roly]

With headphones the sound is quiet fine, but when i hear over the speaker, it is strange.
If the sound is loud it is free from distortion. If than the guitartone gets quieter the distortion starts.

I agree with JM, your description is classic of speaker (or speaker connection) trouble.  You don't want to replace the chip amp only to find that you still have the same fault.

JM calls it "shotgunning", I call it the "blunderbuss method", but whatever you call it replacing parts based on guessing doesn't work.  When you go to a doctor they don't guess on sight but take measurements, poke you to see where it hurts, and repairing amps is the same; we take measurements, try some tests, and see where those lead us.  Then we perform surgery.

A different test here is to connect the amp to a different speaker cab and see if it still shows the same "dirty at low level" fault; but when you say it sounds okay on headphones that pretty much clears the chip amp and points the finger at the speaker (which the headphones substitute for).

I don't know where you are in Europe, but I regularly get Elektor magazine which is a European publication which contains adverts from many parts suppliers, so I suggest you try Googling "electronics parts suppliers <your country>" and you should find quite a few retailers.  Farnell <www.farnell.com> also trading as Element14, Maplin (UK), and Jaycar come to mind.

[diyfalk]

Many, many thanks for the support!
Ich will check the phone-connector with soldering a wire over the switch.
And let you know.

Thank you so far.
Good idea with Elektor and farnell.
I live in .de

best

[diyfalk]

Here are my measurements on the TDA 7240 in DC
Ground to

Pin 3=5,62 V      (Input)
Pin 5=5,67 V      (Output)
Pin 6=12,08 V     (Supply Voltage)
Pin 7=5,74 V      (Output)

next i will test with another speaker and let you know.

Too bad that i can not upload a video (.mov) with the mistake...

[diyfalk]

hello friends,

i checked now with my ac-30 cabinet and it is still the same problem.
When the sound is getting quieter the more distortion came.
hm... :loco

[Roly]

But still clean on headphones?

Was the AC-30 speaker test with the headphone switch contact bridged by wire?

Check that the voltage on pin 2 (SVR and Standby) is well above 1 volt.

To test the Pignose speaker, disconnect it from the Pignose amp and drive it (gently) from the AC-30 output - fault or no fault?

Set the Pignose volume and tone controls to half way (5/10) and inject a signal from an MP3 player or similar between the volume pot wiper and ground (set the MP3 player volume to zero to start - the chip amp has a lot of gain).  Fault or no fault?


If you have clean output from the speaker when driven from an external amp then it looks like the speaker is okay.

If you have the fault when you drive the chip amp from an MP3 player then it does look like the chip amp is damaged (it could still be something else, but that is starting to look unlikely).

If you don't have the fault when the chip amp is driven from an MP3 player then it looks like the preamp stage.

[diyfalk]

But still clean on headphones?

yes

Was the AC-30 speaker test with the headphone switch contact bridged by wire?

yes

To test the Pignose speaker, disconnect it from the Pignose amp and drive it (gently) from the AC-30 output - fault or no fault?

no fault

I found out...
When headphone is plugged in and contact bridged by wire to the ac-30 speakers, signal is clean at the cabinet as it should be and clean on the headphone.
I will check that with the speaker inside the nose.
Yes with headphone and Pignose Speaker no faults.
hm...

Contactspray didn't solve the prob.

The C and R at the Phonejack is not the problem, cause they have just the function to divide the output-signal. 1:10

When i am right, the C 14 & R 10 is a simple LowPass. I will lift them up to see what happens.
Oh much more distortion.

Maybe the C15 0,47µF 50V is the prob?
Oh what is that???
There is no C15 in the board. There is no place for it...