Kel84 input oddity

[Calorgas]

Ok thanks Bob I'll do that and see how I get on

[snowman_al]

I assume you have a digital meter?
If so the first test is to switch the amp off and put your meter on the low Ohms range (200Ω or the like).
Now put one probe in the centre of the Right Aux input RCA and the other probe in the centre of the Right Tuner input RCA. You need to touch the metal part of both at the same time.
You can check with the Left Aux and Tuner RCAs too.

If you get an infinite resistance reading, the problem is with the switch and or wiring.
If you get a low ohms reading there is a problem with the board / relay.

Let us know.

[Calorgas]

Yeah I have a multimeter here which of course broadly speaking I don't know how to use, but when I place the probes in any pair of L (or R) inputs including tuner & aux it gives me a reading of 00.2 which settles to 00.1 after a few seconds (excluding tape out). That's with it set to 200ohms, as far as I can tell. I have added a picture to show how I connected it as I really have no idea what I'm doing and may not have done what I thought I'd done!



In other news, I really don't think I can remove the switch as there's a capacitor right up against it that's completely in the way, and there's practically no scope for movement - unless I'm missing a trick?

[colin.hepburn]

Hi Dave/All
Dave
If you want good parts like Relay Board Kits
Caps and some other components
Etc
Here’s a link to the forum shop just contact Matthew Snell forum administrator if you want something http://www.world-designs.co.uk/components.htm
And Plus a link to Nick Lucas HiFi components which we all use from time to time
https://www.hificollective.co.uk/catalog
Hope that helps if you need something for your amp
Colin

[bob orbell]

We have Dave, was this test with the amp powered up or off ? Bob

[bob orbell]

I think you need to get it to one of us, I am offering, if you remove all valves and send it to me I can sort it, there will be no charge except return potage. Bob

[Calorgas]

Yeah I think this is better off in the hands of someone who knows what they're doing, I think I may have peaked with the diy passive a few years back.

That's a kind offer Bob, I'll send you a pm in the morning.

[John Caswell]

Hi all,
You are not thinking logically. With the power off all relays will be de-energised so all inputs will be short circuit to earth, therefore all phono input centre pins will effectively be connected to each other via the earth path.
The way to do it is stand the amp up normally and connected up, volume to minimum. Power on, input 1 selected and with the meter set to 200R range, measure between the centre pin of the i/p 1 phono and the outer screen of i/p 1 phono, where it should read open circuit. With i/p 1 still selected, measure all other inputs centre to screen the same way and they should read short circuit, note readings, eg i/p 1 o/c, i/p 2,3,4,5. o/c. Then select input 2 and measure same way and note readings eg i/p 2 o/c i/p 1,3,4 5, o/c. when you have done this for all the 5 inputs if there are any anomalies ie i/p 2 selected but i/p 2 and 3 o/c there is the fault.
The wiring to the switch needs to be carefully checked as does the relay pcb for tracks bridged, solder splashes etc. You may need to remove the relay PCB carefully.
Try this and report back

John

[bob orbell]

Yes, I agree John, Snowman's test is wrong and has confused Dave, that is why I asked is it powered or not, I still think that the original builder has the switch index stop incorrectly assembled, I have seen this before. Bob

[snowman_al]

Arrrh,
Apologies, I was not aware the relays switched the inputs to ground when not powered. No schematic is my only (lame) excuse.
Sorry again Calorgas for the confusion.