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First I want to thank the community for all your help and input on this restoration. Just to recap this unit was purchased by may dad in the late 70's. According to the serial number it was built in Feb 1977. My dad passed away 22 years ago the receiver then sat in their home until my mom's...

I was able to get the unit up and running. I removed the "new" F2624 replaced with the old F2624. Biased right on the numbers. Unit has been playing MP3s via aux for 48 hours straight - no issues.

Found this statement: Since bad filter caps don't do so well on filtering, DC spikes can drive the protection circuit crazy and make it act up arbitrarily

First a little background on the work that has been done on the unit: All EC's recapped using the list post on here Dolby board removed all rivets were vacuum de-soldered, wired and re-soldered a few traces were repaired Rotary switch was removed and cleaned Ribbon cable was replaces with new...

Thought I would post a short video of my 9090DB coming back to life. https://1drv.ms/v/s!AvvpJ1teKANUlyqBihh2uNiVvB88 Joe

Can you connect a source with a level control to main in? Yes and is works fine

Mute button is working as designed and in the off position

Yes jumpers are installed

It has taken a long time to get this far. I want to thank all those who have helped along the way. Not done yet but progress. Here what was done so far: System was completely hand cleaned and wiped inside and out. This unit has been in the family since the late 70's All electrolytic capacitors...

I am trying to determine the placement of a black wire that runs from the 2617 broad to the 2544 broad. I believe it attaches to ground on the back side of 2544? Thanks

Why would pushing the mute button cause an arc to occur inside the relay? Thanks Joe

What are the next steps in the recovery process?

I switched to my new 2624 broad.The system is out of protection mode and on the DBT. I took the following readings: The +50V can be checked at either of the F04 and F05 fuseholders. 43vdc The -50V can be checked at terminal 17 or 21/22. -43vdc The +53V can be checked at the junction of R04 and...

The system is in protection mode and on the DBT. I took the following readings: The +50V can be checked at either of the F04 and F05 fuseholders. 32.5vdc The -50V can be checked at terminal 17 or 21/22. -32.5vdc The +53V can be checked at the junction of R04 and C07. 31.5 vdc The -55v can be...

Okay no meters connected fuses installed and unit will not come out of protection mode. What is next?

Well if i remove the DVM from the speaker terminals the unit comes out of protection mode

It's the weekend time for Joe's latest report. So with one DVM connected to the speaker "B" terminal and the other DVM set for mA and inline across the fuse holder, fuse removed. Unit comes out of protection mode and I can set both channels for voltage and current. Remove the DVM insert fuses...

I able to set both voltage and current on both channels when using speaker "B". Is this okay?

I do not if this makes difference but when i set the speaker selector to A+B or A+C voltage seems to settle down.

No change switching meters around

Not really any change when tapping on the relay.

Yes the unit is out of protection. Yes volume at minimum.

Here is a short video showing both the current and voltage https://1drv.ms/v/s!AvvpJ1teKANUlTsn72W2GHXlqjjE

I have been able to set the bias current to 20mA for both channels. The voltage however is a bit difficult seems to jump around a lot.

C16 has been reinstalled. Here are the current voltages The +50V can be checked at either of the F04 and F05 fuseholders.= 46.6V The -50V can be checked at terminal 17 or 21/22 = -46.6V The +53V can be checked at the junction of R04 and C07.= 44.5V The -55v can be checked at the junction of...