Hi Roly

I have a couple of accutronics reverb tanks already from old amps. One is a full length 6 spring from a big combo (which is obviously too big for this amp), and the other is a short 2 or 3 spring, which is ideal, but i think i already tested that a few years ago and it didn't work, although i just clipped leads to it but the amps onw tank was still attached.  I think i'll desolder out the Prince tank when i take pictures of it and try it again.

My favourite reverb of all time is the accutronics in my USA 1990's Fender Princeton Chorus, which has the best clean sound (i know i said that about the Prince, but it's similar to the Prince, but in stereo and with reverb!).

Hi JM

I mean't it's 2" square around the thickness, probably less at the sides.  It is about 6" long. I can't recall if it has one or two springs, but i think it's working correctly. It's a consistent sound, just not a good sound. Have you ever heard a Danelectro Corned Beef 'reverb' pedal? It sounds similar to that, but worse.  I probably exagerated the description to get attention with the post. Maybe more like a bee trapped in a aluminium tube in a shower room! At full tilt it can just about do a kind of Dick Dale surf thing (badly) but there's no sublety to it at all compared to a Fender reverb, though the reverb knob itself works fine.

Do you mean desolder the wires from the pcb where they join to the lugs of the tank, or wires somewhere inside the tank?

You've just noticed that knob!? Yes, the A 440 knob is a tuner. It's like a click-on volume knob/ tone generator. It's tuned to 'A'. There is also a screw/ dial thing on the back to tune the tuner to  'A' more finely. There is also a trim pot on the pcb at the opposite end to the gain knob, which also adjusts it.  I don't use it, though it works perfectly.  I always wish that knob was for tremolo, so the whole amp would be more like a Fender Princeton.

I'll try and take a picture of the inside of the tank when i do the other photos of the gain input/ circuit.

Thanks for your comment

Paolo

Hi

I have a Prince Piggy-2 PS200R amp that has the most pitiful reverb ever. It sounds like someone throwing a metal pipe down the stairwell of a block of flats! I was wondering if replacing the reverb tank with an Accutronics would improve this situation? I realise the tank is not the only factor, but it's the main one.  I will also point out that i would be putting the new tank in the base of the amp cabinet.
As you can see from the picture below, the tank it'self is a ridiculous (one spring) 2" square emarrassment to audio electronics! 

I'm familiar with the concept of matching input and output impedances from other similar discussions on other boards, but how close do they have to be?

The measurement for the input is 208 ohms and the output resistance seems to fluctuate between 214 and 330 ohms depending on whether the amp is switched on or off while measuring. I am measuring where the wires from the PCB are soldered to the lugs on the input and output, as this reverb tank does not have those RCA type connections, it's all soldered.

I have looked on the accutronics website, and while i could get a match for input resistance, the output resistance is quite a difference on any of the models.  Failing that, could the pcb component values be altered to accept the different impedence from the accutronics tank?

Any advice or comments greatly appreciated! More detailed photos on request.

Paolo

Hi Guys

I really appreciate all the time your spending on this and advice you're giving me!

I think i really have to step up to the plate now and get stuck in, now that that you guys have identified the potential faulty area and slung some theories out there. I don't understand most of the technical language but i'm sure it's informative for the other parties to speculate on.
Unfortunately, i don't have any one at hand with electronics knowledge that can assist me, but I definitely need to try and trace that part of the circuit myself and start learning about this stuff, as Phil suggested. I think i will probably have to draw it out in my own way though, as i can't relate schematics to actual pcb's.  In other words, it will be a drawing of the PCB
with linking lines denoting the connections.

I also think Teemuk and others are right about the quality of the photos, so i will do some new ones in the next day or two, focusing on the problem area. (Thanks for those photography tips Roly!)  As i said, initially i just wanted to get the whole pcb in the photos and i'm a beginer with this stuff, so i didn't know what people would want to see the most.

Until i get the new photo's done and try and check the circuit path, i have another (definetly simple!) question about the reverb, which i will make a new post for.

I've tried that Phil, along with every other variation on the dials and inputs.  The only thing that really makes any difference is if i turn the reverb all the way up, the background faint overdrive is a bit more prominent.
The boost input is really just like the high and low gain inputs that you would get on a standard Fender amp, although there is more of a difference between the two. The gain control seems to act more like a mid and treble boost on either input.
BUT,Since you mentioned the boost channel i think i may have now found out something that may be helpful regarding this: 
I have a EHX LPB1 (clean) booster pedal, and the thing i've found is that if i plug into the Boost input of the amp and turn the level knob on this pedal up past 9 o'clock (normal unity gain) the overdrive starts to work! Similar to the way a valve amp overdrives with more of a hotter input signal. Turned up fully there is a massive Marshallesque crunchy overdrive. (This only seems to work using the Boost input at low house volume. I assume it would do the same in the normal input with the amp volume cranked up more.) So there must supposed to be something that boosts the signal once it enters the amp and before it hits the gain knob or stage that is at fault. I hope we are getting somewhere with this idea!! If anyone  would like a more detailed close up of that input/volume/ section of the PCB, let me know.

J M Fahey - I was thinking that i would have just had to use it as a clean amp with pedals as i have been doing, but the above discovery has proved that it did indeed once work as a gain knob. By the way, thanks for the link to the Freestompbox place, but i couldn't register on that site to see it for some reason (i'll try again later). I would have thought that the old skool PCB on this amp with big patches of solder and no component i.d marks and numbering would make it even harder to trace!

Here is a site where there are pictures of a few Prince amps: http://fr.audiofanzine.com/prince/

Included in this is the Prince Piggy-3, the deluxe version of my amp, which has additional Mid and Distortion controls.  When i saw this i thought the gain on my amp must just be for mid/treble boost like JM Fahey suggested, since this had an actual knob for distortion, but now i'm pretty sure the gain is there waiting to be reborn!

There are also a few owner reviews of the Prince Piggy-3 on Harmony Central here: http://www.harmonycentral.com/products/123165

PS - I've just re-read those Harmony Central reviews for the Piggy-3 and realised that the last review by Egbert Griffioen was his review for the Piggy-2 which was on the old Harmony Central site (before they junked all the thousands of user reviews and started again from scratch - what a waste of all that wealth of information!) There also seems to be a review of a Piggy-1 in there also.  They must have grouped all the old Prince Piggy reviews under Piggy-3, assuming that was the last model.

Anyway, i'm eager to hear your comments on this new development!

Paolo

Roly -

Thanks again for replying!

Unfortunately though, i'm just really a beginer like i said above and don't understand alot of this advice, even though i'm sure it's excellent!  I could just probably test with a multimeter and replace components as directed.

The gain is there in a weird distant manner like i described before, so i assume it must have been there originally (otherwise why have a gain knob if it didn't do anything?).

I suppose i'm not technical enough to be on this forum. I thought it might be quite easy to diagnose and fix.

Teemuk -

Firstly, i posted this question in the 'Newcomers' section beacuse it suggested BEGINERS post their amp questions here. I am a BEGINER in electronics and have only modded a few things, where i have been told, or given diagrams of what to replace on a PCB.  I can barely read a schematic never mind trace one out.  I can see a burnt out component or loose wire and have a multimeter and soldering iron.

I took the photos to show a general overview picture of the front and back of the circuit board, so people could see it was an old fashioned pcb and what type of circuit. From there they could make suggestions as to what components create gain in these type of amps, and hopefully suggest testing/replacing certain types of components, that i could do myself to see if it could be fixed.  I wasn't even really sure WHAT to photograph at this stage. People might recognise the type of circuit and have similar experience of what went wrong even if it's a different make of amp. You suggested this type of circuit has transistors for the gain stage - that's the sort of thing we need to know.

The pots are wired direct to the PCB and i could barely get the thing out of the faceplate as the connecting wires to the jacks, etc have obviously been wired after the PCB has been screwed down and positioned (you can see the strain on the wires in at each end on the underside photo), therefore i did the best i could photographing the PCB.  Like i said, if anyone wants closer, more detailed pictures they only have to ask, though i can only zoom in on what's already there.

As for seeing the whole thing, that is the whole thing. There is just a transformer and reverb pan that you can't see which is in the photo below.

Again, i'd be really grateful to anyone who wants to help with this problem and offer advice.  Please remember though that i'm just a beginer with this stuff.

Thanks, Paolo

Thanks Phil and Roly for the advice and heads up for Irfanview.

Just to clear it up. The manufacturer is Prince and the model name is Piggy-2, and the technical model reference name is PS-200R. They also came in Black tolex and a wooden case like the original Boogies.  There is also a a Prince Piggy 3 which looks very similar , but also has a mid control is slightly bigger like a Fender Deluxe size.  I have pictures somewhere.

Anyway, i've re-sized the original gigantic photo (above) of the amp, and here are some photo's of the PCB and insides. The gain control area is over in the right component (top) side, and on the left from the underside view.  Again, any help in solving the gain problem would be much appreciated.  If anyone wants even more closeup photo's i'll try and do that.

Paolo

Hi, i've just discovered this forum, so hello to everyone.

I hope someone can help me with an issue i have with my Prince (Piggy) PS-200R.  It was made in Japan 25w SS blonde tolex combo with a 10" speaker modelled somewhat on a Mesa Boogie Mk2B. It was made around 1979.

It has a gain control, but all it seems to do is work just the same as the regular volume control.  It was like this when i bought it off ebay a few years ago. If i turn the gain all the way up, and just have the volume on a tiny bit, you can hear an overdrive sound but it is very quiet and in the distance/hollow sounding. If i turn the volume up more than that everything goes clean again.
As i've modded amps and pedals, i 've had a look inside and can't see anyhting loose or burn't out. Because it's a 70's amp the circuit board is a bit different than a modern pcb. It is also pre- op amp chips. If i knew what was wrong i could fix it myself. These amps are very rare now and there is no real info about them on the internet.

I love this amp. It has the best clean sound; It's warm, woody and chimey and sounds like a valve amp. I use pedals for overdrive, but i'd really like to hear what the amp's original gain sounds like!  Any help would be gratefully appreciated.