Old EH Low frequency compressor

[01redcobra]

I've got an old Eh low freq. Comp that's not working. Seems that it looses the signal at the first op amp which is a UA741c TO99 style. And I have no signal at the CA3080 on any pins. There is a signal at pin 3 on the 741, but that's it. I have a schematic, but it doesn't show the CA3080 that's in the photo. First question is, can I sub a newer style UA741 in place of the TO99 style one? And does anyone have a schematic that shows that CA3080? I hate to sub out the 741, but I have been unable to locate one that's the original style. Can anyone give me some advice? Thanks in advance!

[Mark Hammer]

Excuse my ignorance, but TO99 style means the small round metal can?

If so, a standard plastic DIP will sub for it easily, but you'll need to make sure you assign the pins correctly and that the pins can reach the pads that the previous package might have used. Sometimes I see metal can packages installed on boards with two lines of 4 pads, such that they can be used with DIPs, and sometimes I see them used with pads laid out in a circular pattern.

Just as a tip, you can usually find datasheets online for almost any chip by googling the part number and 'pdf'. So, entering CA3080 pdf" into google gets you this: http://www.google.ca/search?client=f...=Google+Search

[01redcobra]

Yes, it's the small can type amp. I would prefer to stick with that type as it will affect the originality of the unit, but the dip may be the only way to get it functioning. Thanks much for your input on this!

[52 Bill]

Yes, it's the small can type amp. I would prefer to stick with that type as it will affect the originality of the unit, but the dip may be the only way to get it functioning. Thanks much for your input on this!

You can try checking with companies that sell obsolete electronics or eBay for that matter, for the 741 in a metal case. It may take awhile, but one may turn up.

Until then, I'd suggest that you look for a "wirewrap" 8 pin dip socket. These have long leads that can be bent to match the circular pattern of the pc board. Then you can use a standard dip package chip. They used to make adapter boards that essentially did the same thing but at 10 times the price.

Hope this helps.

[01redcobra]

Thanks Bill, I located a 741 with the round metal can frrom a place called electronics plus out of Calli. It was a bit pricey, but the pic they showed is exactly what I need. Still looking for a schematic though.

[52 Bill]

Glad to hear you found what you wanted.

I forgot to mention earlier that the metal case style is designated by the letter "T". So if you search for uA741CT you should find the correct case style chips.

Is this unit called "Low Frequency Compressor"? Or is it one of the usual funny/cute EH names?

[01redcobra]

Yeah, it's actually called "Low Frequency Compressor" The fella that brought it over believes it's a compressor for a bass. He buys and sells equipment and got in a grab bag with a bunch of other pedals. Someone sold him the bag of effects for next to nothing and he's found out that 2 or 3 of the pedals in there are selling for over $500 on Fleabay. Some guys have all the luck! I never fall into these kinda deals. Guess it's the right place, right time senario. Thanks for your input on this Bill. I'm still trying to locate the proper schematic. I'm not sure that the 741 is the problem for sure yet.

[Mark Hammer]

Boy, do I feel dumb. When I view posts from work, they block photobucket pictures, and don't even let you see the link to know that a picture is being shown. I didn't realize until I looked at the thread from home that you had a picture.