No update for a week because I switched my multimeter to diode test instead of high voltage, then checked the HT in the SC200 which made it light up pretty well. Was waiting for a new one to arrive and doing boring guitar setups.
Now new one has arrived, tested relevant stuff like the bias and HT and various resistors in the SC200 with no valves in it. Everything looked fine there. Loaded it up with a different phase inverter valve and it runs fine again, even with two blackened KT88s, guess they’ll need changing, might get them tested, see how they have lasted. Looks like it was a short phase inverter causing the trouble, same thing I had with my first Sound City 120. I sort of suspected but thought it was unlikely. One more guitar to wire up which is being a pain, and I can get on with the Burman, yay.
Heres what the valves from the SC200 look like after whatever made them redplate a lot:
This arrived today, quick clean of the box and photos and in the pile cause I have loads to do. The SC200 has decided to go wrong and red plate half its valves and smell bad, waiting for it to discharge its caps and cool off before I get in there (managed to gimme a belt last time).
In need of a proper clean up.
Insides, nothing super fascinating, nice lacing.
Awesome pot crust. Not sure how this happens. Probably related to all the basketweave peeling off the case though.
Fighting apathy from the start today. Turned out my instinct was right because nothing went well. Switch for the Roberts guitar arrived:
Not even nearly the same, sort of assumed I’d get the right thing ordering from dude who made guitar, told me that’s all they have and the only sort they used. Did offer to take it back though.
Powered up carlsbro without valves to see if it works, an all the voltages are too high, over 800v on the plates. Not right. Impedance plug is in right place, wondering if some wires are switched, but don’t want to slap the 120v setting with 240v in case that’s not the issue, need a step down to try it. I want to get playing with my Burman, have ordered caps for it.
New amp arrival, once this is going, hopefully will be main bass amp, is handier than the SC200, is 140w, might just be enough.
Been sat about a fair while. Mystery grub on it.
Lovely Burman insides, although some is replaced after a bit of a being on fire incident. This is made for KT77 and EL34 don’t take the voltage so well.
This is one my singer picked up. Suggested he give it to me for a going over before he fires it up. Much easier to check things first than have to fix it exploded (see TVM earlier). Looks like it has already had a recap, dust and cobwebs say might ahve been a while back, so sign of explosion goo, but signs of a reasonable job of teching. Still needs an IEC instead of that Bulgin though:
This came to me with an apparently dead pickup. Whipped it out, works fine. Lot of fiddling with the complicated switching, and its the switch that is dead. Also it hums loads. Problem here is there is no shielding in it, not even shielded wire, aside from the pickup wires. And with loads of slack in the wires, is pretty much ideal for humming if that is your aim.
Started on the correction. Too tight to shield it all, the cavities are very oversized so would use loads of tape, and I only have a bit left over. Replacing all the signal carrying wires with screened wire an shielding the switch section, because that has most exposed wiring will have to do. Should be quite far ahead of how it was. Just awaiting a new switch, Roberts were helpful enough with this.
Also, here is a pic I took of the bias mod I did to the Carlsbro 50 top featured earlier, first time I’ve done this, used the dummy load for the first time, very exciting:
Trim pot attached to cut off legs of the previous resistor, preset to about the same value, so minimal turning with it in place, 1 ohm resistors added to the valves to measure the current. Used this calculator to check what it should be: http://www.ax84.com/biascalc.html?Bvolts=441&maxW=25&BiasCalcAction=calc
Kind of a poorly thought out overexcited purchase, not useful in the slightest, and not very interesting, not a guitar amp.
Doesn’t look like a valve amp on the front.
But inside, valve rectified and stuff.
Pretty neat inside, inked solder like a Hiwatt. Pair of GEC KT66 is probably of more interest than the amp. Hit me up if you want it though.
Other purchases, box of electrical bits from a charity shop, hoping this was a variac which would be really useful:
Turns out it is actually part of a tank radio: http://www.pyetelecomhistory.org/prodhist/prodinfo/pthc-ws19.pdf
Also this came with it, cool, and not useful at all:
Oh, picked this up yesterday too:
Bit of a holy grail sort of pedal. Laying about a mate’s place where he intended to get it fixed. Figured inside it would be of interest to people. Turned out to be a right fiddly pain in the arse to get into.
Figured it would be the 4 screws and the two halves would separate, but no, knobs off, and the top is just a cover that is spring over the jacks and the knobs, so have to bend it a bit to get it off, an carefully due to thick chippable paint. And once you’ve done that, still can’t get at the guts:
Top panel off too and it looks a bit more sensible.
At every stage plastic spacer bits dropped out of it, really annoying, look out for those if you are taking one apart.
Only actual issues where the disconnected battery snap and the board mount jacks having pulled out the solder, bit of easy soldering and done.