A few years ago I posted the actual hfe of Q1-Q4 from a 1974 Rams Bead Big Muff with FS36999 transistors as measured using a Peak DCA55. They were: Q4: 163, Q3: 214, Q2: 171, Q1: 160.
Since that time I've worked on three more pre-1975 Rams Head Big muffs. Two had FS36999 trannys and one had 2N5133 trannys. Guess what...they all measured less than 200 hfe, lol. The one with 2N5133 trannys were as follows: Q4: 132, Q3: 117, Q2: 145, Q1: 128. I also noticed Kit Rae posted some of his own...
I thought this might be of interest. It's a kind of modulated doubling delay.
This particular unit is quite distressed. I've traced it to help debug it.
Switching and power are not shown. It has it's own plug, and i couldn't be bothered to follow the wires around a transformer and bridge rectifier etc. There's a couple of regulators for +15V and -12V.
I'm not very experienced with this stuff, so please take it all with a grain of salt.
Crazy this doesn't seem to have been traced before.
I was compelled to trace this unit as the only available schematic (a factory one at that) didn't match what I had infront of me.
Noticed differences between factory schematic and my trace:
•There's numerous resistor value differences
•A whole output buffer added
•No resistor between ground and the + input on the final all-pass stage.
•The colour switch and blend labelled the right way.
•No input 'pulldown' resistor.
This vintage octave-up/ring modulator showed up on Reverb for just a few days. Here are the seller's pics if anyone wants to trace it. The only adjustments are two trim pots. The instructions are posted on Effects Database and are included here for continuity. Apparently Thurlby is still in business in the UK, as Aim-TTi (Thurlby Thandar Instruments) which manufactures test equipment and power supplies.
What sort of psychotic madman would do this....
I've worked on Mutron Filters over the years, including a month ago but this is insane.
They stuffed it in the control cavity
Topology looks different, three batteries - one for the LED's, two for power or it has a separate power supply box with multi pin cable.
Several intermittent things, looks like a severe pain to work on.
I have Germanium transistors knocking about as in the picture and some AC128 that I can't find at present. :roll: In my hand there 10 red dot, just the 2 white dot and a roll of OA47 diodes maybe 500 or more. Are these transistors NKT275 as they were bought here in GB back in the early 1970s? This site goes on & on about Fuzz Face diodes and about 10 page downs they mention red and white dots on canned transistors.
I might have more somewhere as I have a lot of older components like...
OK, I’m finally digging through my pile of vintage pedals resurrecting them from the dead. Here’s a mid 70’s EH Echoflanger. If anyone has gut shots, schematics, layouts, info, etc. to get this puppy up, that would be greatly appreciated.
I received a yellow Colorsound Wah/Fuzz/Swell, probably dated ca. 70ies pedal to replace the scratchy pot. The pedal had been in repair for that, but the owner re-installed the original pot again because the pedal did not behave right after the installation of the new pot. This has several reasons (see lateron). Since changing the pot(s) on this pedal presents a problem I would like to share with you how I managed to fixed it. Skip on to the quintessence on the bottom if you do not want...
Hello everyone, this is my first post here and I am looking for some help. Please keep in mind that I am a novice with electronic repair and reading schematics but I am learning. So I’m starting my journey into pedals with a phase 100 script circa 1975. It came in the mail a few days ago and while it mostly works it does have a couple problems.
It is a little bit of a noisy pedal but that might go away after it warms up a bit or if I change its location in my chain, I’m not sure about that....
hey guys.
I have some germanium transistors with oxidation on the terminals, and the cover also has a little oxidation.
I'm currently scraping the terminals with a craft knife.
The question is... is there any product that helps remove oxidation without damaging the transistor?
grateful
Looks like this thread got lost during the great downtime? Just a quick recap:
These are essentially rackmount versions of the Ibanez stompboxes of the 808/9/10 era (although many of them are subtly to very different) including an MN3007 based flanger and chorus and MN3005 based delay (at least by the AD9 days the Ibanez delay was 3205 based IIRC). The problem is that, without the pedal, you can't engage the pedal in any sort of way, it just sits there...
Hello everyone
I built a tonebender mkii, after some transistor choices I have the following parameter.
the sound is not bad, but there is doubt about the lack of leakage in Q1. Is the resistor sufficient?
trimpot Q2 and Q3
9.88v
HFE/Lk (DC55) C B E
Q1 AC128 - 65/0.036mA 8,00
Q2 NKT72u - 76/0.063mA 0.47 0.11
Q3 2N1309 -242/0.403mA 8.04 0.46 0.38
I put a 2m2 resistor Q1 collector base
I've never had a mkii in my hands, so I don't know if it's looking good.
Any tips?
thanks
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