Univox EC80A help needed

[Blood_mountain]

Hi folk,

I’ve got a Univox EC80a tape echo that is semi-working, and I’d like to get it fully working but am not super tech-savvy. It powers on and passes audio, but there is a definite volume drop and it’s muddy. There Is currently no echo to this echo machine! The echo delay speed seems to work - tape motor speeds up and down accordingly. No clue about the repeats as I can’t hear them. The echo balance is where I think the main problem is. Going to fully wet there is no sound at all from the unit. Also, and this seems super weird, if I put my fingers on a certain spot on the circuit board, I can get a radio station to tune in. I have a short video I took of these issues if anyone is an expert and wants to have a diagnostic look at it. Any help would be greatly appreciated!!

[Ben79]

I think the radio phenomenon is probably normal. Off the top of my head I think these used a cartridge, do you know what state yours is in?

[Blood_mountain]

I think the radio phenomenon is probably normal. Off the top of my head I think these used a cartridge, do you know what state yours is in?

It was in bad condition when I got it, and I did a DIY fix on it with my limited knowledge. Cleaned it all out, put new pads in it, relooped the tape, etc. - but I'm not super mechanically inclined, so maybe the loop that I've put in there is not functional - these tapes have the traditional 8-track/4-track loop that is a continuous loop that unravels from the center, and I've created just a basic 5 second linear loop - maybe it won't work that way? I just thought for the purposes of testing and fixing the basic loop should work. I've got two "new" tapes coming in the mail for it, so maybe those will help.

I've been on some other forums and these units seem to be plagued with similar issues. I'll monkey with it here and there until I've exhausted the extent of my abilities.

[Dr Satan]

Make sure the cart is pushed in all the way. If it's a PLAYTAPE and not the ones made for it, you have to modify the unit or cart to work. Also, if the little back door is missing, the tape probably isn't being pressed against the heads firmly. Hold the cart in the slot firmly and see if it works then. And yes, the radio thing is a feature. EDIT- I have seen people fold up a piece of paper and wedge it in under the cart to maintain firm contact with the heads.

[Dr Satan]

Oh, and I'm not sure how the biasing is done on those, I'd have to look at a schematic, but if it's anything like an Echoplex that uses an oscillator to get the voltages for the heads, you'll need an analog meter to set/measure that voltage. For whatever reason DVOMs just won't show the voltage output of that type of oscillator (I forgot the name of it). I've tried the cheapest Harbor Freight DVOM, all the way up to my Fluke meter and the only thing that gives accurate readings is the $10 POS meter with a needle. So long as you use the same type of tape, you shouldn't have to rebias it, but if you change the type of tape, you gotta adjust for best performance. I have some old carts from a radio station that (supposedly) use the same formula tape as the old echoplex stuff, but I find that blank 8 track tape actually works better. Of course, that's pretty useless information now that I think about it because the machine you have uses that really narrow tape like in a cassette, lol. Anyway, good luck with it.