HELP: Unknown Vintage Canadian Tube Amp

[Drexl Jonez]

DJ,
The Beltone schematic posted by Mick is almost certainly right.

Overview for an introduction:
Note that Points labelled "A" on the schematic connect together, ditto for points labelled "B", "C" and "D"

Point A, B, C are power supply feeds to the various stages.
Point D is the tremlo low frequecy signal usd to modulate the signal volume via control of the input stage 6AV6

Starting at the top left:

6AV6 input - 1st audio gain stage with the tremlo low frequency oscillator signal applied to its cathode to modulate the tube operating point (and hence the amplified guitar signal output from this stage) via the link lablled "D" which connects to the tremlo oscillator output point labelled "D".

That input gain stage drives Volume Control and the Bass/Treble Tone Control.

Output of the volume and tone controls drive the next 6AV6 (top center) which is the second audio gain stage.

The output of the second gain stage drives the audio output tube, the 6AR5. Note that a 6AQ5 can be used instead. This is your audio power output stage. It is good for about 4 Watts maximum.
TDSL Tube data [6AQ5]

The 3rd 6AV6 (bottom left) is the tremlo low frequency oscillator. It generates the control signal for the tremlo function.

The 6X4 is the power supply rectifier tube.

For your info:
The 6AV6 is a single triode which has identical specs to each of the 2 triodes in a 12AX7 dual triode.
The 6AQ5 (6AR5) is VERY similar to a 6V6 but in a smaller 7 pin tube.

You will need to check that the tubes are OK but apart from that, all that is likely to be required is to replace old electrolytic capacitors. That is, the 2 off 10uF / 350 Volt capacitors and the 2uF / 350 Volt shown at power supply points A, B and C.
Values are not critical, a 4.7uF or even a 10uF will do for the 2uF, 10uF or 22uF can be used for the 10uF, just make sure you use 350V or higher rated capacitors. The 6X4 rectifier is rated to handle up to 40 uF maximum as the 1st filter capacitor but I suggest you don't go above 22uF.

It might also be advisable to change the 10uF / 50V Volt electrolytic cap shown on the input stage (top left). Its value is a little more critical, stick to 10uF with a voltage rating of 50 Volts or more. Using too big a capacitor here could compromise the tremlo function.

I hope this is of some benefit to you.

Cheers,
Ian

Thanks a million for taking the time to lay this all out, it will be much helpful to understand this amp (and tube amps altogether) before I take it to a technician. I have yet to have it tested but will do so after it gets a fuse and a fuse box as well as a brand new grounded plug since it will be plugged to a 220V converter.

Thanks again Ian!!

The information you quote regarding the AGS-500 is incorrect. It may well be the same model, as the basic amp was re-branded for different markets, but the speculation that it's 25W RMS or 50W peak is incorrect. The source has determined that from the 120v input voltage and 1A fuse. 1A is just the fuse rating and is determined on the basis of how much current the amp draws on a cold switch-on, and how much current the amp can safely stand under a fault condition before the fuse blows to protect it. You can't speculate on the power of an amp in this way.

You also can't add another rectifier to increase power. It has a single dual rectifier (two rectifiers inside one glass envelope) which is what 99% of tube rectified amps use.

Hey Mike,

Thanks again for all that useful information. The reported info mentioned was from a "squier" forum, I have no real technical idea about what it truly meant. Like I've mentioned before, a decent 4 Watt would do just fine. I haven't spent a single Euro/Dollar for this amp so if it kicks back up, re-tubing and changing a few components shouldn't break the bank. Even if it requires a speaker, at such a low wattage RMS it still shouldn't cost much for the overall project.

I'm ordering a fuse (2,0A 250V (50/60Hz), 6,3x32mm, transparent glass body, nickel plated brass contacts) and fuse box so it can get tested with the current tubes.

Thanks again Mike !!

[Drexl Jonez]

Hi,

I hope I won't get stoned for reviving an old thread!!

I have taken the amp to about 4 electricians in southern Italy and NONE of them had any idea what to make of it. One even argued it was a broken radio... Italians 😒😔

I've gotten a fuse holder and a box of 2A fuses but since everything came unconnected, with loose ends, I'm not sure how it all connects together before I can even start replacing Caps or testing anything.

The indicator light and fuse holder are completely loose. There are two loose wire coming from the chassis, one from the power cord and one from the Transformer. There is also a loose wire coming from the AC switch, also connect to the transformer.
There is nothing else, no resistor connected to the indicator. I guess the loose wire from the power cord goes to the fuse holder and the loose wire from the AC switch goes to the Fuse, but I'm not sure exactly how the indicator light fits in there.

I've drawn a rough sketch of the "situation". I have no access to a competent tech here so hopefully one of you wizzards will be able to help. I've already got plenty of great inputs regarding that little amp here! 😁

Thanks!
https://imgur.com/1tclr0a

[dmeek]

Looks like you would connect the two wires to the fuse holder terminals, plug it in to 120 Volts AC and see what happens.
If the indicator is a neon with internal resistor (it probably is) it would be connected as shown.

https://music-electronics-forum.com/...1&d=1567179779

[Drexl Jonez]

Dmeek, thanks so much for taking the time to draw this! That's great I'm going to try this tomorrow.

This is the indicator https://imgur.com/WYOzHim