Repair Dynacord Echocord S65

[ward]

I'm repairing a Dynachord S65, and I'm stuck.
It came to me without the tubes and tape and was in a very dusty and rusty state.
Maybe someone here has some experience in troubleshooting something like this.

Here's the schematic:
http://www.peel.dk/Dynacord/Echocord_Super_65.html

So far I have replaced the rectifier, and c27, c28a, c28b. (c28 was leaking badly.)
I've cut a tapeloop from a standard 1/8inch audiotape.

Voltages at the tubes are:
Tube1:  134/0/1.2 // 135/0/1.2
Tube2:  118/0/1.2 // 119/0/1.2
Tube3:  53.7/0/0.4 //  55/0/0.4
Tube4:  119/0/0.8  //  116/0/0.5
Tube5:  41/0/1.4 //  -100/-3/0
Tube6:  279/-121/1.5  //  279/-124/1.5

The second triode of tube 5 is completely off ? 
If I follow signal from "instr1" or "instr2"
i see signal with bias at pin7 from tube5
at pin6 from tube5 only bias.
What could this mean?

 

[RuudNL]

Cathode resistor of tube 5 broken.
Faulty tube
No filament voltage

 

[ward]

A tubechange does not dramatically changes the voltages I read at socket 5.

Resistance to ground at pin 8 is 1k, at pin3 it is 1k6.
Is it ok to measure this in circuit?

Edit: to be sure I replaced R36 and C24 at pin 8 of tube5.
No big change. anode at -75Vdc, cathode at 0Vdc, pin7 at -1.8Vdc.

 

[RuudNL]

There should be (almost) no voltage between pin 7 and ground.
On pin 8 you should have a positive voltage referred to ground.
Are you sure you measure - 75 Volts at the anode of Tube 5 (pin 6) ?!
This should be a positive voltage! What is the voltage you measure over C27 ?

 

[ward]

I remeasured voltages at tube5,

definitely:
pin6 : -70Vdc  ,  103Vac!?
pin7: -1Vdc  ,  0.8Vac
pin8: 0Vdc

Voltages over
C28b=313Vdc,
C28a=277Vdc
C27=235Vdc           

 

[ward]

The coil at tube 5 was open.
I replaced it with a transformer used as coil.

So far it works,  mut maybe it needs more work.
I'm checking with a guitar and amp this weekend.

 

[RuudNL]

I suppose you can use any Hi-Z choke here.
(Or a tube output transformer, primary 5000-8000 ohms.)