Carlsbro Cobra 90

[Pleb]

Hi Peeps, I've just enroled on the forum. Has anyone out there got a circuit diagram for a Carlsbro Cobra 90? I just bought it for a tenner. It just decides to go off whenever it feels like it, 10 minutes later, 20 minutes later, sometimes an hour later. I'd appreciate any help on the subject. Oh, as well, has anyone got a circuit diagram for my Carlsbro Marlin PA150?. I've tried Carlsbro.com, it seems it does'nt exist anymore.
Regards,
Pleb.

[JazzAudioDesign]

I've just bought a Carlsbro Cobra 90 Lead amp in a pawn shop that had a similar problem. The fix was to clean the effects Send jack switch. To see if the problem is the switch, plug a guitar cord between the Send and Return jacks. If the problem is not there anymore then, it's the switch in the jack. The headphones jack has a switch too that disables the speaker when phones are plugged in. If the switch is dirty, you can loose the sound too. So it is best to clean all the jacks (switched or not) with contact cleaner or Caig Deoxit then insert jack in and out a few times. You can also replace the jacks. Someone on the Internet also mentionned a similar problem with the Cobra keyboard amp and the problem was a bad solder joint on the bridge rectifier. Those effects loops jacks switches problems are very common on all brands of amplifiers and the symptoms can be no sound at all, intermittent sound, or low volume/distorted/noisy/erratic sound and it can happen even if you never or barely use the effects loop. Hope that helps.

[PhaseLockLoopy]

Like the Jazz guy said Effects send/return

I used to work on 100's of these - Ivor Green was the designer - I used to work for him in the mid 1980s

Arnt you lucky

...NOT

go straight to the rear Return/Send sockets -- the switch links pre to power stages

the contact is always cracking up -- a small needle file and a bit of servisol switch cleaner and you should be ok

If it looks like more than that - call me back

[JazzAudioDesign]

Hey PhaseLockLoopy !

Do you know who made the speaker in those Cobra 90 Lead amps ? This amp is a really simple and good design. It is very loud and good sounding for a solid state amp. I tried it with my bass too and it's amazing for a guitar amp. Lots of power and low mid growl. We don't see much of those in Canada...most Carlsbro's I've seen here were solid state bass amps. They were loud, clean and expensive because of the import from UK....

[wahab]

Surely Celestion speakers..

[PhaseLockLoopy]

Originally Posted by wahab

Surely Celestion speakers..

Correct

There was a time on the very early one's of using Fane - But once the contract with Celetion was sealed on all Cobra's and Stingray's, Carlsbro didnt deviate very much

I never like the EQ on these amplifiers -- too restrictive -- I think it would have been better to complememnt the two Baxandall circuits with a pair of sweepable parametrics