Guyatone Rolly Phase Sonix PS101 help needed.

[col]

I have been given a Guyatone Rolly Phase Sonix PS101 to repair but I have several problems. The plastic op-amps have had the numbers filed off but at least two of them are 1458s as I can still make that out. I supect the other one is as well. There is also a metal can op-amp which forms the oscillator and seems to be working fine. This has had the part number obscured by permenant marker but ends in CH. All the transistors say K30A 0 on them. My main worry is that it looks as if some parts may be missing as there are holes on the board which look like they may have had components or wires in them at some point.
Another item which is problematic is that the case is at approximately the mid-point voltage rather than 0v. I have checked for voltages on all pins which look correct and have traced the signal part way through the circuit but have lost it in the most densely populated part of the board and don't want to bend it around too much in case the connecting wires break off. Many of the wires are joined with shrink tube on them and I have checked tham all for conductivity and are OK.
If anyone has a schematic or a picture of the board of one of these it would be useful to see if it is at least all there before I carry on.
I understand that the pedal has been in an attic for around 25 years and I can believe it. The cardboard box is in better condition than the pedal which is dropping paint everywhere and the external screws are badly corroded. Some of the caps don't look too clever but they do seem to be working.

[col]

Found something!!!

http://www.modezero.com/rolly-box.htm

If i can get it working I'll try and do a schematic

[gez]

Another item which is problematic is that the case is at approximately the mid-point voltage rather than 0v.

What were you using as reference?  Could it be that you mistakenly thought a trace was ground, when it wasn't?

Re holes in PCB.  Is there any solder around them, or are they clean?  I've come across this in a few commercial FX.  It seems the manufacturer/designer simplifies the final design to save on parts.  Having said that, I modded a cheapo delay for someone last year that was based on a Boss.  They'd made a mistake with the PCB and left out a cap so had to bodge the design to get it to work; they ended up simplifying that section because of the mistake and there were spaces where components should have been.  End bodge job meant a lack of bass responce.  Because of the missing cap, I had to do a fair bit of 'creative soldering' to change the circuit to Boss spec, which was obviously what was intended by the 'designer'.  I bet the PCB designer had his nuts in the vice over that one!*

* Or nips in the clamp (don't want to be accused of sexism).

[col]

Gez,

I measured the voltage from the 0v on the battery. I have now identified most of the holes as where the leads should go but instead they are just soldered to the traces on the other side. If you look at the picture above you'll be able to see that the holes are there as well so I don't think there is anything missing. Where the metal can opamp is there are also holes for a standard plastic bodied one so I guess they just used whatever they had, although the board in the picture is identical to the one I have apart from the resistors on mine are all brown rather than green. From this picture i cna make out that the other op-amp is a 1458 as well so that solves that one! I get a clicking from the LFO when it is on, and I have measured the voltages changing so that part is working. I can also trace the signal through two of the op-amps. It's unlikely I'll get time to do much with it this week but I'll post on here what I do find if I get it working,

Col

[Mark Hammer]

At least two of the dual op-amps can be productively replaced with 4558s or something else a little better than a 1458.  There ARE places where a 1458 is needed, but this isn't one of them.  The change won't be huge, but you should get a bit less hiss if I'm right.

It would also appear from the modezero picture that there are unused pads on the stock unit.  Of course, I don't know if these are the same unused pads or empty holes as you see on yours.  It's not uncommon for a layout to have blank spots where previously-thought-to-be-necessary components were abandoned without changing the layout.  If the board works and the footprint wouldn't be appreciably altered with a redesign, companies usually say "Screw it" and leave things as they are.

[8mileshigh]

Col,

I used to have one of these but my switch broke before I got into DIY and I sold it on Ebay.  I hope you can get it working, it's a very nice phase shifter.  Check with Disco Freq, I think he's got a schem at his site.

Ok, just found it linked at Freq's site, good luck making it out. http://www.voxamps.co.uk/downloads/circuits/1900phas.jpg

Chris

[col]

Chris,

I just found that! It didn't come up last time I did a search but aparrently Guyatone made this for Vox as the 1900 phaser and he has a schematic on his site. That should help me work out where the signal is disappearing. The metal can is a 741.
I have a Guyatone Phase shifter PS019 which is great but it looks to be totally different to this. Guess what! It has 3x4558s and a TL062.

[col]

Once I had the schematic it took me 2 mins to sort! Audio probes are great!  One of the 1458s had expired and once replaced and a quick slight adjustment of the trim pot it sounded great. There is some hiss but it's not intrusive and since it's not mine I'm not to bothered about that. I like this phaser but not as much as my Nobels.

[ilcaccillo]

Tried this pedal one time at a shop, and it was amazing.
I really liked it.

it seems that is was made by Locobox , so probably Locobox did OEM for Guyatone and Vox

check the website here:

http://www.locobox.com/guyatone_box.html

http://www.locobox.com/70s2.html

[alteredsounds]

What a coincidence! I have had one of these in the collection for a few years and dusted it off for a play a few days ago.  Pretty nasty switch on the thing that was very intermittent, so replaced that, now it works as I remember, lovely phaser, has a kind of auto-funk feel to it, much like the 70's PT models.  Only thing it has now is a mass of background hiss that I'll track down and fix.  For an amazing sounding old phaser look for a Dharma Sound phaser, best I've ever heard for a vibe-type feel