Cambridge P50

[Xapito]

Hi

Bought one of these units but the left channel, altough functional, has lots of white background noise which seems to increase while the amp is warming up. This is the 2 PCB's version and from past experiences with Sansui mainly I suspect that some transistors are busted.

I've narrowed the transistor's list to:

2 x me8002 - (replace with 2N3700, 2N3701, 2SC2235, 2SD667, 2N2405?)
2 x c1121
2 x c1122
2 x c1123 - (replace with NTE123AP?)
4 x me4101

But I'm having problems sorting the matching replacements, has anyone done this service in the past that can throw a light here? Thanks.

[The Barbarian]

I had the same issue with a 'P60' many moons ago. It must have been down to one of the transistor because that is the first thing i swapped out, i swapped the lot so can't say which was the culprit. Maybe James {Istari Knight} is the man to guide you with replacements, i know he likes farting about with things like this..

:D

Which reminds me my old Trio 'TK150' amp blew out some nasty smelling black smoke the other day, must get around to that. Being Germanium jobbie that should be fun.

[Xapito]

Ouch Germanium... got a Philips RH591 that uses them, beautiful sound!

Reg the P50, I also believe it's one of the small UFO transistors but I'm having trouble getting the replacement compatible ones. :scratch:

[The Barbarian]

You selling the '591'?

:eyebrows:

[Xapito]

Family heritage, sorry! But I think I know where there's a 590 for sale, could confirm if you want, only difference being the front balance dial. :ner:

James called at the front desk!!

[The Barbarian]

:(

[istari_knight]

Felipe, it certainly sounds like a leaky transistor. The fact its noisy will make it easier to find... In situations like this I use "Servisol Freeze It 20" simply spray each transistor, when you spray the faulty one the noise will stop... Its that simple.

I'll have a look at modern substitute's in a minute, bare with me...

[istari_knight]

ME8002 = NTE128

ME4101 = BC546C

2SC1121/2SC1122/2SC1123 = NTE123AP ... Hard to be 100% on this as there are no online datasheets but I can't see a problem they are all very similar & NPN.

Of course with modern replacements pin-outs are often different even if they are an electrical substitute so you'll have to study the schematics to work out your EBC's...

[walpurgis]

Always fancied trying a P50. Never got my hands on one. Many years ago I did briefly try a P80 I believe it was, but it was a bit iffy and I couldn't get a real idea of how these Cambridge amps are. The P50 was very highly regarded in its day. As were the Goodmans 'Module' series amp/receivers that everybody seems to have forgotten now. Still plenty of 5 series and 6 series Armstrongs about, they were OK too.

[istari_knight]

I had a P100 which was a complete PITA. Sounded great when working but it needed everything replacing to keep it alive... The pcb's were on hinges and all of the connecting wires had gone brittle with age, lifted one pcb & the wires all disintegrated !

[Xapito]

James, thanks for your valuable input on this, will follow it. Regarding the P50 from what I could hear, even after testing dozens of integrated units, it does standout sound wise, I do find it similar to the aforementioned Philips RH591, thunderous bass and good treble projection.

[The Barbarian]

It's the 'Classic One' that's the beauty

[Xapito]

You've lost me, never even saw one for sale. Any improvement SQ wise compared to the sheeps out there?

[The Barbarian]

O yes a good amp was not many tho..

[DSJR]

Alex has 'mine' and it sounds dire by modern standards :scratch: Could be a P60 though :rolleyes: