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psl amplifier info


fireman

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hi all, been looking at some past posts and have managed to get some info but would like some more if possible.

 

I have a PSL vp1012 amp that has been solid as a rock for the past few years.

 

its been stored for over a year and now has an intermitent output, bangingthe amp brings the output back (very technical)

 

kevinE mentioned in a post about these amps suffering from output relay problems, is this all psl amps or just certain models?

 

also I would like to know how the active clip led is supposed to function, I have always presumed that the green led comes on to show that a signal is present at the imput but what happens when the amp clips (apart from the speakers dieing) do they change colour,flash or go out?

 

one more could anyone tell me what the vp led is, only noticed it yestarday!!

 

as always thanks in advance to any info

 

p.s. user manual would be great.

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Hi kevinE,

 

thanks for the reply, Ive been investigating further and had the top off the amp, the output relay is a NORSLO R15, 3PDT.

rang them today and it is obsolete, and the replacement part is now also obsolete!

 

dont know how old this amp is but it seems ancient now.

 

tapping around the relay with a signal going through the amp results in the output coming and going on either or both channels, is this the symptom that you have had in the past?

 

going to get the board out asap and check then solder side for cracks and dry joints, seems to be only the contacts ,if it is the relay, because you can't hear/see the coil moving when the output is lost.

 

then again it could be something after the relay I suppose.?

 

cheers .

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I'm afraid the Norslo relays are the ones that fail. The brass parts seem to lose springiness somehow and they no longer press against the static contacts with enough tension for a reliable contact. The last time I had a PSL with this problem (they were never a very common brand, were they!) the Norslo relays were still available so it was no problem to change them. You might be able to gently adjust and clean the moving contact to make it more reliable; sometimes disgarding the perspex lid will ease the pressure on the cradle where the connecting wires rub against it.

 

You can get similar ones from Omron if you're prepared to drill the board to accept the offset pins; others may be available if you hunt around. The other option is to make an intermediate pcb that sits on stilts and can accept a more robust relay.

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That might be a reliable option! Speaker relays cause grief in alot of amps, the output current can be quite high but the contacts must also be able to pass small currents without complaint even as they age and tarnish. They are often responsible for the common symptom of the amp only working if the gain is turned up to max and then back down again, temporarily clearing an intermittent contact in the relay.

 

I recently repaired a Cloud CV1000 where one relay had turned into a molten mess due to a simple bad contact.

 

PSL amps arent the easiest to work on, make sure you arent breaching any insulation or isolation distances by mounting a new relay too close to dangerous voltages elsewhere in the amp. (goes without saying really!).

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You'd think that choosing a relay, or indeed a switch, was an easy job. Just pick one with the right current rating. In reality it's way more difficult than that. If you find the datasheet for a relay from a decent supplier you'll see that there are a huge number of different current ratings which cover all sorts of operating conditions - DC vs AC, making vs breaking, etc etc.
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hi brian, I know what you mean about choosing the right components, I had a harrison amp that went DC and welded the output relay CC, taking a speaker with it.

 

in fact I still have the amp, I was going to try and repair it but didn't have enough arms and legs to pay for the output transitors. worked out cheaper to buy a new amp with waranty from our german internet friends.

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...I had a harrison amp that went DC and welded the output relay CC, taking a speaker with it. ...

Hmm, Harrison. Now there's a company that did some interesting things when it came to spec'ing components!

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