Fender Super Twin.

[Marcel]

There are heaps of places to get bits there Doc.

I find Ebay is often quite reasonable, but sometimes you do need to do some hunting around... For most electronic bits I usually try these Australian Online sites first...
RS components - http://au.rs-online.com/web/
Jaycar - https://www.jaycar.com.au/
Element14 - http://au.element14.com/

The two Ebay sellers below I have bought from have been quick delivery and have a reasonable variety of stuff. Think both have 5Y3's in stock..
Vicmazz - https://www.ebay.com.au/sch/vicmazz6...1&_ipg=&_from=
Amptubes - https://www.ebay.com.au/sch/amptubes...1&_ipg=&_from=

There are plenty of others (mostly Asian) that have similar and often cheaper stuff however often they only sell in quantities of 100 or more. That's way too many tube sockets for my needs... one site I got 3 Chinese made 12AX7/ECC83's for AU$32 which is pretty damn cheap.

I'm keen to build a EL84 amp... something akin to a Vox AC15... but that will have to wait until I get all my guitar builds done...

[DrNomis_44]

Update:

Went to my local Jaycar Electronics shop today and bought some red and black coloured banana plugs, some red and black alligator clips, and some red and black wire, these are for making a set of new test leads for my ESR Meter and the component tester on my 25Mhz Dual-Trace Oscilloscope, I think I'm going to be needing them when I finally get round to doing some servicing work on my Fender Super Twin amp, will be making the new test leads tomorrow.

[Marcel]

Don't make your ESR leads too long. I've found 10cm to 15cm is usually plenty long enough. This is especially true for your capacitance meter as the stray stuff from leads will give you wildly false readings on the smaller value caps.

[DrNomis_44]

Don't make your ESR leads too long. I've found 10cm to 15cm is usually plenty long enough. This is especially true for your capacitance meter as the stray stuff from leads will give you wildly false readings on the smaller value caps.

Good point, although it's probably not going to affect the component tester on my 25Mhz Dual Trace Oscilloscope, it's one of those old school ones with a Cathode-Ray display tube in it, the component tester in the Scope uses the X/Y function to draw a straight-line, or elliptical shape on the screen for a basic go/no-go test result display, it's good for quickly testing semiconductor devices out to see if they're good or not, I'll post a pic of my Oscilloscope later on, but yeah I'll keep that in mind, cheers mate.

[Marcel]

I have a hand held LC meter which I use to check various coils and caps. You have seen it in earlier photos.

I also have a set of 10cm leads for it for the bigger stuff, plus a very useful and accurate little PC board with 2 pins spaced the meters terminal width apart and a slot cut between the 2 copper halves so I can check surface mound bits. It gives accurate measurements as it has near zero lead length.

[DrNomis_44]

Update:

I've been doing some testing of the original preamp Valves that were installed in the sockets of my Fender Super Twin's chassis, I tested them by plugging them into the 9-pin socket of my Baja Real Tube Overdrive pedal, and also the preamp sockets of my little Legacy 5 Watt valve amp, one thing I did notice is that they all sounded a bit weak in gain, taking into account that the 12AT7 and 12AU7 are lower-gain twin triodes, so, I'm assuming that they are all getting a bit worn-out.

I've had a look through Evatco's stock of preamp tubes and have decided to go with a set of new JJ brand valves as replacements for all of them, here's a list of the stock preamp valves and their replacements:


V1: 7025, being replaced with a new JJ 12AX7/ECC83S Gold Pin.

V2: 12AU7, being replaced with a new JJ 12AU7/ECC82.

V3: 7025, being replaced with a new JJ 12AX7/ECC83S Gold Pin.

V4: 12AX7A, being replaced with a new JJ 12AX7/ECC83S Gold Pin.

V5: 12AT7, being replaced with a new JJ 12AT7/ECC81.


I may even go ahead and replace all the original valve sockets too, the sockets for the six 6L6 power valves do seem to be a bit loose, so maybe a set of new ones will do the amp some good, might also get some new spring retainers while I'm at it.


Might also be worth having a look under the doghouse cover and see if any of the supply filter caps need replacing with new ones.

[Guvna19]

any pics please Doc?

[DrNomis_44]

any pics please Doc?

You mean pics of the amp?, I've already posted some in this thread a few pages back.

[Marcel]

I'd have thought you'd build yourself a little tube tester in a die cast box to confirm or deny your tubes, but I suppose the Baja pedal does the same thing.

As most measurements would be DC based they can be pretty simple fixed resistor units with banana sockets for metering points. A fixed self bias for the smaller tubes maybe with a optional capacitive audio in/out is easy to implement, Larger tubes are an issue for current draw and fixed bias but it's not beyond the realms of possibility if you use reasonable sized VA transformers.

On the subject of transformers I am considering a purgatory pedal build powered by a 12VAC plug pack and having a 240:12V 3VA transformer to create the HT which I calculate should be plenty for one 12AX7, so using similar for a test box should be easy.

[DrNomis_44]

I'd have thought you'd build yourself a little tube tester in a die cast box to confirm or deny your tubes, but I suppose the Baja pedal does the same thing.

As most measurements would be DC based they can be pretty simple fixed resistor units with banana sockets for metering points. A fixed self bias for the smaller tubes maybe with a optional capacitive audio in/out is easy to implement, Larger tubes are an issue for current draw and fixed bias but it's not beyond the realms of possibility if you use reasonable sized VA transformers.

On the subject of transformers I am considering a purgatory pedal build powered by a 12VAC plug pack and having a 240:12V 3VA transformer to create the HT which I calculate should be plenty for one 12AX7, so using similar for a test box should be easy.

I would have built myself a Tube Tester but unfortunately i don't have the parts needed nor the money to buy them, so I used my Legacy amp and Baja Real Tube Overdrive pedal as the next best things, i must put building a Tube Tester on my "to do" projects list.