Hello - I recently bought a nice pair of Celestion A compacts which I hooked up to my beloved PP1. Unfortunately, the right speaker had a defective crossover which took out the right channel of the amp. A small wisp of smoke appeared somewhere near the vent holes in the lid, sort of near the middle of the circuit board (the right channel circuitry is towards the rear - I picked up that much!)
Anybody got any experience with these or at least has a coupel of suggestions? I can solder if told what to do, but fault finding with amps is above my pay grade! 🙂
![IMG_0976[1].JPG](https://www.diyaudio.com/community/attachments/img_0976-1-jpg.1150100/ "IMG_0976[1].JPG")
Anybody got any experience with these or at least has a coupel of suggestions? I can solder if told what to do, but fault finding with amps is above my pay grade! 🙂
If you can find one! But the wirewound resistor (2nd from right) looks cooked. My PP2 (twin transformers) has a 33R 3W in that position.
So I suspect the associated output transistor let the magic smoke out. TIP 146?
So I suspect the associated output transistor let the magic smoke out. TIP 146?
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I think you're probably on the right track.
I tried Googling "albarry pp1 schematic" and got a lot of candidates. I suggest comparing your board with those images and trying to find a match. Having a schematic helps enormously. Keep us posted.
Good luck!
I tried Googling "albarry pp1 schematic" and got a lot of candidates. I suggest comparing your board with those images and trying to find a match. Having a schematic helps enormously. Keep us posted.
Good luck!
Thank you for that! Certainly no schematics available! The interesting thing is that the one that looks cooked is on what I think is the board for the left channel, but it is the right that isn't working - will get another pic from the other direction.
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You can create your own schematic with careful scrutiny of PCB. The circuit is not terribly complex and bottom side traces are relatively visible through the board. It's a tedious process (Speaking from experience), but very helpful in exchanging ideas with members and a great asset for any repeat maintenance.
Like others here, I can see that there are several schematics and fragments of Albarry designs on the web, including a great analysis and commentary on model M1008 and mods by Andrea Ciuffoli. http://www.audiodesignguide.com/Albarry/index.html
Most appear to have a common basic design and selection of semis with variations to suit power, size, cost etc. and this is useful because it makes it easier to identify parts and draw your own circuit diagram of that rare PP1 model, which probably never had any service documentation issued anyway - just the offer of return-to-base service. Therefore, you need to glean all the general info carefully and make use of what's available as a guide to what you may or may not have - then draft your own schematic. I wouldn't assume that anyone else is going to do it for you unless they have already been through the process and can scan what scraps of info they may have kept.
Most appear to have a common basic design and selection of semis with variations to suit power, size, cost etc. and this is useful because it makes it easier to identify parts and draw your own circuit diagram of that rare PP1 model, which probably never had any service documentation issued anyway - just the offer of return-to-base service. Therefore, you need to glean all the general info carefully and make use of what's available as a guide to what you may or may not have - then draft your own schematic. I wouldn't assume that anyone else is going to do it for you unless they have already been through the process and can scan what scraps of info they may have kept.
An easy way:
Currentless. Ohmmeter.
Measure the power transistors and the power resistors in comparison with the left channel.
Conceivably, driver transistors and the "bias" transistor (the small one on the heat sink between the power transistors) are still defective.
All transistors should in no case have a value close to zero ohms when you measure e.g. collector to emitter.
I would start as simple as that.
Currentless. Ohmmeter.
Measure the power transistors and the power resistors in comparison with the left channel.
Conceivably, driver transistors and the "bias" transistor (the small one on the heat sink between the power transistors) are still defective.
All transistors should in no case have a value close to zero ohms when you measure e.g. collector to emitter.
I would start as simple as that.
There is a schematic on the excellent Paul Kemble web page I jave built a clone but using Sanken output devices
Trev
Trev
If anybody's interested, it needed 3 power transistors, 2 output resistors and one bridge rectifier. I'm told the previous chap had put in some overkill caps which didn't suit the rectifier.
If you like the design, build a small single ended in it. 4 or 5 parts. The heatsinks should be able to cool at least 2 x 10 Watt power dissipation. You would only need an other transformer.
The only High End Albarry on planet;-)
The only High End Albarry on planet;-)