Randall RD-5 not happy..

[Sea Chief]

If it is muted, that would explain it.
Tapped secondary at either 4 or 16 Ohms I expect.

Ive just done a test of the good switch (6x tiny legs into the pcb they have, not 4x).. & testing continuity between the end pair of legs connected together (I surmised gnd) & one of the middle legs: if the switch is pressed in, there is continuity, if depressed out, there's a break.

This good switch is labelled 'Left' (pressed in) and 'Gnd' (pressed out).. I have no idea what the heck it is. Is it of relevance-?

anyway, ok if I do the same test on the broken switch identical legs.. I get continuity. Which, if I'm correct, signifies the button -is- stuck in the mute position! (could I be right-? if conversely tho it's stuck in the non-mute position.. I'm back at square 1).

thanks- SC

[Sea Chief]

On the schematic the awol switch is over at C7 (like geography map orientation). It is SW4.

Schematic is found via post #5 or so, there's a link to the full schematic.

thanks, SC

[Sea Chief]

Ok better view of awol SW 4. What I seem to have as well, is three vacant holes next to it. J10, J11.. & another hole with "10 mm" nearby too.

Looking at the preamp board, where I see J5 for eg, is a wire connector, so can I assume J means ' junction'? Im finding this switch area on the schematic very confusing. There's a strange 'JMP' ( jump? Connector?) next to it.. cant make head nor tail of it around here.

Im wondering if some spotty herbert, has gone heavy metal ballistic, the 6v6 let go, & thinking the mute switch suddenly became engaged as reason for no sound.. jammed something in/ at the mute switch, in his 'very metal' mental mindset. Maybe he took out a connector too.

[Jon Snell]

SW4 turns the speaker off!

[Sea Chief]

SW4 turns the speaker off!

Well I gathered that just by the word 'mute' on it. But as it wasnt there I thought only that it wasnt affecting anything, IE it cant mute.. I mean how can something thats not there do anything-? (was the reason I hadn't mentioned it).

Ok I cant decipher the area around SW4 on the schematic. Switches I find -the- most confusing, especially with 6 legs! What Im thinking is, either remove it, or, link pins on it.. IE bypass it, or regig it to be stuck in its opposing switch position.

Do you know if either option would work Jon?

Or best just replace it with a new one? Have you any idea what the vacant j10, j11 could be? I cannot find on schematic.. but.. I see a strange 'JMP' on it, in this very vicinity.

thanks. SC

[Sea Chief]

SW4 turns the speaker off!

Sorry, is your implication here to suggest that Ive been so stupid, the amp hasn't worked because I hadn't depressed one switch-?

It seems to suggest this is what you think.

[Jon Snell]

Not at all.

It is a trap that we all fall into from time to time. It's part of being human.
Hopefully, with a new 6V6, all working now.

[Pixel]

It would be best if you could replace the broken mute switch. Can you see any part numbers on the good switch? That would be a clue to finding a replacement that fits well.

It looks like there is nothing at all left of the broken switch internals, so it isn't stuck on mute. If it was on mute there would have been a 10 ohm resistor load on the OT. Because the mute switch is "missing", the load on the OT would have been due to R59 and R60. I'm beyond my pay-grade here, but that could have burnt out the 6V6. The good news is that the dead 6V6 may mean the OT is ok.

[Sea Chief]

Not at all.

It is a trap that we all fall into from time to time. It's part of being human.
Hopefully, with a new 6V6, all working now.

Ok good. If that had been the case Id hold my hand up as the biggest eejet. No I just didn't realise the mute button being absent, could possibly be stuck 'pressed on/ muted' with most of it physically missing. How its in this position Ive no idea either.

No Jon I've no clue still how to get it working. Ive emailed randall asking for what switch it is.. but dont expect much help. So replacing it is one plan.. but Ive still got these 3 mystery holes nearby, if they contained a junction wire before (but cannot find them on the schematic). Then working out the switch in the schematic to know how, if I could, tweak something to bypass it maybe. And what JMP1 is too ( something related to mystery j10, j11 ..who knows).

Tubes with 9 pins are complicated but 2 less as heaters means only then 7.. but switches with 6 bloomin pins & 2 positions, I find the worst to understand on a schematic. Like a mini shroedinger's 6 legged octopus. A jazzmaster one with 6 pins & 3 positions.. & I need a week of mental help.

thanks SC

[Pixel]

Don't worry about the vacant J10 and J11. Does JMP1 have anything connected?

[Sea Chief]

Don't worry about the vacant J10 and J11. Does JMP1 have anything connected?

Hi Pixel. I can't even located JMP1! another way I find schematics so difficult. What is a jmp.. Ive never heard of one tbh.

[Pixel]

Hi Pixel. I can't even located JMP1! another way I find schematics so difficult. What is a jmp.. Ive never heard of one tbh.

Oh, I thought you found JMP1 on the pcb. If you are worried about JMP1 on the schematic, just forget about it. It is an optional jumper.

[Sea Chief]

It would be best if you could replace the broken mute switch. Can you see any part numbers on the good switch? That would be a clue to finding a replacement that fits well.

It looks like there is nothing at all left of the broken switch internals, so it isn't stuck on mute. If it was on mute there would have been a 10 ohm resistor load on the OT. Because the mute switch is "missing", the load on the OT would have been due to R59 and R60. I'm beyond my pay-grade here, but that could have burnt out the 6V6. The good news is that the dead 6V6 may mean the OT is ok.

Hi Pixel, well in fact half of the switch -is- still there, the base bit with the tops of the 6 legs is visible in the photo. As said I tested the other switch, with the DMM leads in a certain position on two specific legs, & the switch pressed in > 8ohms. I depress it > infinity.

If I repeat the same test on the broken switch, DMM leads on the very same legs, as it is/ in its broken state > I get 8ohms.

Wouldn't this suggest then that the broken switch is in the 'pressed-in' state? (IE this switch pressed in = mute).

I thought I had this conclusively established.. but maybe not so-?

Thanks, SC

[Pixel]

Hi Pixel, well in fact half of the switch -is- still there, the base bit with the tops of the 6 legs is visible in the photo. As said I tested the other switch, with the DMM leads in a certain position on two specific legs, & the switch pressed in > 8ohms. I depress it > infinity.

If I repeat the same test on the broken switch, DMM leads on the very same legs, as it is/ in its broken state > I get 8ohms.

Wouldn't this suggest then that the broken switch is in the 'pressed-in' state? (IE this switch pressed in = mute).

I thought I had this conclusively established.. but maybe not so-?

Thanks, SC

The mute switch is a DPDT switch, which has had its "legs" connected together in pairs so it might as well be a SPDT switch. All the internals of the switch are gone so the 6 legs are just connected to 6 points on the circuit board below. There is no switching going on anymore. What you are measuring is either the resistance of the 8 ohm speaker or the 10 ohm resistor.

[Sea Chief]

The mute switch is a DPDT switch, which has had its "legs" connected together in pairs so it might as well be a SPDT switch. All the internals of the switch are gone so the 6 legs are just connected to 6 points on the circuit board below. There is no switching going on anymore. What you are measuring is either the resistance of the 8 ohm speaker or the 10 ohm resistor.

Dammit. I was sure I had it sussed! ok I understand what you mean mostly. The speaker was n/c so it must be the resistor then.

Back to square 1 again then. Urgh.

(unless the mute position is the button in the out position, & the broken switch equates to this position, & pressing it -in- means unmute.. seems unlikely though).