Kay 703C or not

[Pryde]

Maybe the wrong area to post but excuse me if so.

I have here a Kay 703C (schematic attached) that was free to me that is not functional but all original from what I can see. I see this things typically need a good isolation transformer, 3-prong cord, recap, etc) just to get up to par.

I have not worked on an amp needing an isolation xformer such as this but have been researching it a bit for my own learning. That being said, I would like to salvage this for fun and am not opposed to gutting and throwing in a 5F2A circuit or the like.

As I am open to either path pretty equally, what would you folks suggest with this one. Are these little kay 703's worth fixing up? Listening to a few on youtube they sound pretty fun but given the odd tubes and not sure the investment it will take I wonder if gutting would be a better choice.

BTW: if I do end up restoring this circuit I will most certainly need some guidance.

I appreciate your thoughts.

[The Dude]

Hard to say if it's worth it. It is to some people and not to others...... a matter of preference, I suppose. Do you have an isolation transformer for repairs on your bench or access to one? If so, plug the thing in and see if makes a sound that you like. I would probably do this anyway before I started sticking money into the thing. You could go through all the trouble to purchase and wire an isolation transformer into the amp only to find out the caps are shot, the OT is shorted and the tubes are bad. In short, start with seeing what you actually have to work with.

[Pryde]

Hard to say if it's worth it. It is to some people and not to others...... a matter of preference, I suppose. Do you have an isolation transformer for repairs on your bench or access to one? If so, plug the thing in and see if makes a sound that you like. I would probably do this anyway before I started sticking money into the thing. You could go through all the trouble to purchase and wire an isolation transformer into the amp only to find out the caps are shot, the OT is shorted and the tubes are bad. In short, start with seeing what you actually have to work with.

Unfortunately I do not have an iso transformer for testing. I suppose I should get one for these such things. Normally I would pass on messing with it but since it was given to me I thought I might try to learn a bit with it. What iso transformer would you recommend to have for testing purposes? particular hammond model? How do you normally hook it up for testing? (i.e. solder it, aligator clips, etc.?)
Thanks

[olddawg]

I would not recommend using it as is. However, realize that people used these for years. I MIGHT be tempted to plug it in and measure the voltage from the chassis and input jack ground to earth. If it is negligible, wearing good shoes and not standing on wet concrete, I might test it. If you have a guitar transmitter setup you would be isolated while playing guitar. But .. an isolation transformer for a small amp like that is only $20-25. But honestly... IMHO.... Those amps are crap even in perfect working order. Don't expect a Champ. Entirely subjective of course.

[Pryde]

I would not recommend using it as is. However, realize that people used these for years. I MIGHT be tempted to plug it in and measure the voltage from the chassis and input jack ground to earth. If it is negligible, wearing good shoes and not standing on wet concrete, I might test it. If you have a guitar transmitter setup you would be isolated while playing guitar. But .. an isolation transformer for a small amp like that is only $20-25. But honestly... IMHO.... Those amps are crap even in perfect working order. Don't expect a Champ. Entirely subjective of course.

I am leaning toward gutting. I have been trying to trace this one through and some of it is not making sense with the schematic. For example there is no R9 56-ohm series resistor in the heater line at all. There are other weird anomalies as well. I am thinking a little tweed princeton circuit on the cheap would be fun in here.