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^ No, there is not a metal strip. The wood trim attaches directly to the bottom of the faceplate using 4 small machine screws.

did you check the fuse in your multimeter?

They are available second hand in T80 tuners..

Did you try to check bias?

That swinging arises when the channel is being over biassed and as the current rises in the output stage the current clamp (TR15/17 and TR16/18) pulls the output stage down until the clamp lifts and the cycle starts over. The fact that both channels are doing it suggests an incorrect component...

If the tuner is not responding it suggests power supply failure from F2619 which in turn is fed from R30 on the power supply board.

FWIW the main problems, Dolby board and green plastic flex cables, were resolved - in production changes - by September 77 according to opinion elsewhere in this forum, so your December 77 unit I would expect to be free from most of them.

91mm centre to centre on the bumpers. I also note that the overall dimensions of the cases of the 8700/9700 are the same except for the depth which is 20mm greater on the 9700.

Oops posts crossed....

When measuring bias using this (direct) method the intention is to replace the power supply fuse with a test milli-ammeter. So you need one test probe at on end of the empty fuseholder and the other probe at the other end of the fuse holder, thus completing the supply circuit. If you get the...

The dimensions are above in post#8

The volume pot is shown on F2693 to the right of the Dolby board in the schematic.

^ Yes

I presume you wish to know the magnitude of the signal required to cause full scale deflection of the meter? To calculate that we would need to know the coil resistance. In the absence of that value I can only estimate/guess that full scale deflection would require around 300 micro amps/200mV...

F-2693 is shown to the right of the dolby F-2654 and switchboard F-2655. The loudness taps are included on 2693 and are in parallel with a switch contact which is presumably the loudness control though I haven't checked right through..

I use a boiling kettle to steam them off.

Had a very similar problem with my 9090DB. Turned out that I'd mounted the filter/muting switch assembly upside down thus putting the muting switch where the hi filter should have been...

No doubt. I've just tried again without success. The page requires that I login -although I'm already logged in - and then rejects my credentials. It's something that has happened previously but I don't recall how/if I fixed it.

The post immediately above your post contains a link to the ak database which contains the service manual but I don't think you will get access to it as a non-subscriber. I am a subscriber but also cannot get to it. I suggest you go to highfiengine.com where you can download it free but you'll...

Sounds like some DC offset to me.

This is a spare I have for my 9090DB. The knob pulled off easily though there are some traces on the plastic shaft that may have been some adhesive...

That 150W DBT is too large and may be affecting DC offset. Should be 100W.

I'd start by checking all the internal power supply fuses. The arcing may have caused one/some of them to blow..

They are obsolete but Digikey offer a substitute as part number 0010321041