Help me fix a vintage "808" - No output ! FIXED !!!

[R.G.]

here's an example that i found on the internet and i ran in superspice.  the basic problem is that the voltage divider only works when the current is the same in the two resistors (R1 and R2 for this example).  here's one way you can mess that up:

The inability of the resistor/resistor Vr generator to supply/eat current is oen of the important points in my article on designing voltage references at GEO.

I guess people don't read that stuff much anymore.

[gaussmarkov]

here's an example that i found on the internet and i ran in superspice.  the basic problem is that the voltage divider only works when the current is the same in the two resistors (R1 and R2 for this example).  here's one way you can mess that up:

The inability of the resistor/resistor Vr generator to supply/eat current is oen of the important points in my article on designing voltage references at GEO.

I guess people don't read that stuff much anymore.

ouch, that hurts!     i rely heavily on your stuff R.G.  i even remember reading that article once, but now that i go to look for it with google it doesn't come up with it (as far as i could tell) with "voltage divider" or "voltage reference."  which article is it?  Designing bias networks to provide Vbias in effects?  i generally use the google "site:geofex.com" all the time as my quick entry into your work.

and with the power of the new search function provided by aron i can count my direct quotes from your pages.  10 posts out of 234 total i reference your pages.    and that doesn't count the number of times i have written to you directly ...    you are the best R.G. and don't you forget it!   

[MartyMart]

Thanks RG, that's shed some light on the matter, I think I can follow this through now
and find the culprit !
The fact that this unit "was" working for 22 years and has recently "failed" without any
modification, would wipe out "solder bridges" etc so I "MUST" have a bad part that's
bleeding voltage back into VR/elsewhere.
I have new 1% resistors for VR and a new 47uf cap which I Know are good.
I'll take readings of everything following VR and see if I can find the voltage
increase as you've described.
Thanks again,
Marty.

[MartyMart]

Traced voltage back through VR and the 10k's/NP caps were reading over 8 volts
on the op-amp side !!
Pulled the chip and it had evidence of "burn up" along all the pins
Socketed and fitted an NOS 4558 ( just to keep it original)
She fired right up

Also put new electro's everywhere and made the NP caps 1uf poly's
which is always a tight squeeze.
No other mods, the guy want's it kept original
Happy Happy Happy !!
Thanks all for invaluable help, RG in particular, you ROCK !!

Marty.