06 August 2011

Quick MXR '74 Vintage Phase 90 Fix

I recently purchased an MXR '74 Vintage Phase 90, but it had a couple of problems when I received it. First, the back plate bulged outward in the middle. I took it off, placed one end on a piece of wood and kneeled on it until it was straight. When I placed it back on the pedal, it was a very tight fit, but the bulge was gone. However, when I tried the pedal, it didn't work. The pedal sounded normal off, but when it was engaged, there was no phase effect. It sounded like a slightly muffled version of the clean signal. I removed the backplate, checked the battery, and looked around inside for anything obvious, but did not see anything. I tried it again before putting the cover back on, and the pedal worked fine.

Based on that, I assumed that two things that shouldn't touch were touching. The only thing I saw that could be doing that was the lug on the output jack that carries the signal. It was pointed up about 60 to 70 degrees, I would guess (about where the red line is in the photo below). I think this could have been touching a solder point on the bottom of the circuit board through the foam when the cover was on. I bent it down (gently), replaced the cover, and it has worked consistently ever since.

Original position of lug is indicated by the red line. I bent it down to its current position.
I read some reviews stating that the pedal  didn't work when received. So, if this is a design flaw, and others have had this problem, I thought I should make this info available. Especially because if you buy the pedal used you often don't have the luxury of returning it if it stops working.

Anyone have any similar experiences with the '74 Vintage Phase 90?

31 July 2011

Biyang PH-10 Phase Adjustment

I recently purchased a Biyang PH-10 Phase Pro on eBay. I noticed that in eBay's stock photo of this pedal, SPEED is spelled SEEPED (seriously), so I wasn't sure what to expect. This one's not too bad.

The PH-10, like MXR's M-101 Phase 90 (the natural comparison in this price range), did not sound that great out of the box. I took it apart to see if there was an easily accessible trimpot inside, and there was indeed.

The stock sound was over-pronounced for me. I made careful note of the stock position of the trimpot screw and turned it little by little until it sounded good to me. You may end up with different results if you try this, but I ended up about 270 degrees counter-clockwise from the original position (see pic below). The pedal now sounds much creamier. If I don't sell it first, I will a/b it with an Custom Shop Phase 90 and a 74 Script Phase 90. One thing at a time, though.

The yellow dot indicates the stock (top) and adjusted (bottom) position of that end of the slot.

26 July 2011

Ibanez TS-10 Replacement Switch

I recently bought an Ibanez TS-10 Tube Screamer with a non-functioning switch, but could not find an exact replacement. I bought a Cherry MX1A-11NN for 98 cents at Small Bear Electronics: http://www.smallbearelec.com/Detail.bok?no=588. The listing warns that the switch "fits the opening, [but] needs a piece of wood glued to the actuating lever to press its smaller shaft." That sounded sloppy, so I hoped to find a different fix.

I installed the switch with no problems, and saw that it was indeed too short. I tried small rubber caps (including two that I pulled from the end of bungee cords). They worked, but didn't look good. Cutting them straighter would have helped. The sizes I tried fell off and would have needed glue anyway.

I grabbed two pieces of shrink tubing -- one about 4mm and one about 5mm, give or take a mm. I placed the 4mm tube on the actuator, which was a tight fit, but not a struggle. The 5mm fit over the smaller one no problem. I cut the length to about 8mm and very, very briefly heated them with a lighter, just enough to taper the end and firm them up a bit. Here is the result, which looks good and works perfectly.  Hope this has helped someone. I'd be happy to hear about other fixes for this switch.

21 June 2011

DOD YJM-308 Preamp True Bypass Mod

I don't care that much about true bypass, but a lot of people do, so I wanted to put this info out there. I just completed the true bypass mod for the DOD YJM-308 pedal, and it was incredibly easy. I used a 3PDT switch so I will have the option of installing an LED at some point, time permitting.

First, remove the original switch and replace it with a 3PDT switch. Then wire everything as shown in this photo and crude diagram (bottom view, of course):

It's hard to make out the wiring in the photo, and the diagram is pretty crude, but between the two of them, you should be able to discern where the wires go.

Put everything back together and that's it. All I have left to do is add the optional LED, and then use some nail polish remover to remove Yngwie's signature and name from the pedal. Again, I'm not a believer in true bypass, but I love this pedal. It was a pleasant $30 surprise (it helps to have a good amp, of course). But I'm not a signature model type -- and if I were, it wouldn't be Yngwie's signature -- so the name is going.

I should also add that the battery just fits. And I mean .00000 tolerance. So it won't bang around the enclosure when you move it.

26 January 2011

Maxon OD808 Repair

Originally posted: 24 June 2010
Maxon OD 808 Repair
I bought a Maxon OD808 overdrive on ebay for $22.50 (+$10 shipping). It was listed as not working, but because these pedals sell for $150 new and $60-$90ish used, I thought it was worth a shot.
Based on the seller mentioning a burning smell after the pedal stopped working, I assumed that he had used the wrong power supply.
I was correct. The diode that protects against reverse polarity (D5), had been thoroughly burnt, along with the adjacent DC jack and the circuit board. I read a post by someone who ruined a pedal by using a 2-amp power supply; most pedals this size use about one-tenth of that (200 mA for the math-impaired).
So it was clear that I needed to at least replace the burnt diode, so I started there. A few months ago, I disassembled a broken CF bulb to see what it looked like inside, and I ended up salvaging some parts from it. Among those parts was the diode I used to replace the fried one in this pedal (1N4001).
 So, after an investment of $32.50 + 20 minutes + $0 in parts, I have a $150 pedal, which sounds awesome.