Hey Guys
I'm looking at repairing my A5 as it was full of salt corrosion around one of the SAP15's although the amp has been working!
I have striped it down and cleaned it up and found that C242 on the output board had blown and R12 on the input has fried, while I can see the value on the blown ceramic cap I cannot read the resistor.
Does anyone have a schematic or service manual as its proving hard to find!
I'm going to test all the transistors but as its been working I'm hoping there ok is there anything else I should check?
Thanks!
I'm looking at repairing my A5 as it was full of salt corrosion around one of the SAP15's although the amp has been working!
I have striped it down and cleaned it up and found that C242 on the output board had blown and R12 on the input has fried, while I can see the value on the blown ceramic cap I cannot read the resistor.
Does anyone have a schematic or service manual as its proving hard to find!
I'm going to test all the transistors but as its been working I'm hoping there ok is there anything else I should check?
Thanks!
I managed to get a MK2 documents off Cambridge but that one seems to have used LM3886's the input board looks the same but the circuit refs are different but from the location it seems like the resistor and a cap tie the inputs to the chassis?
Is there a corresponding resistor on the Left channel you can measure or read the colour bans from.
Anyone noticed the error in that schematic? Ground goes to the centre pin of each RCA connector! Shows the care and attention that goes into service documentation in a competitive commercial environment I guess!!!
Thank you!
Thanks bud much appreciated!
Ok bud ill go track those down and take a look.
No its only on the one side.
Turn's out so far I have found the N channel SAP15's are dead (SAP15PY) so the hunt begins for genuine replacements!
Check also RV201 or RV202 bias trimmers depending on which channel has failed.
The value is 100 ohms.
The value is 100 ohms.
I recently sold my 2 A5s, both fully working and in good condition, for around £70 each. You might be able to score a damaged one on eBay or gumtree for a few £ and use the transistor if good. They are a decent sounding amp for the price, but not worth spending a lot of money on.
The best option is to use the STD03N/P transistors, and add an external 0.22ohm emitter resistor. Note that these transistors are "Last Time Buy" and will be obsolete soon. Don't buy them from eBay.
Some answers:
The A300, A500, A4 and A5 amps from Cambridge Audio share the same amp board with some minor differences on the preamp/selector boards.
When repairing a faulty output stage specially with the Sap08/10/15/16 always replace N and P channel devices at same time and also trimpot Rev201/202 and capacitors next to them (C220/C238), and of course check or replace the 1N diodes across the SapXX legs.
There are a few resistors around the MJE340/350 can can burn up in a output short please check.
Good luck
The A300, A500, A4 and A5 amps from Cambridge Audio share the same amp board with some minor differences on the preamp/selector boards.
When repairing a faulty output stage specially with the Sap08/10/15/16 always replace N and P channel devices at same time and also trimpot Rev201/202 and capacitors next to them (C220/C238), and of course check or replace the 1N diodes across the SapXX legs.
There are a few resistors around the MJE340/350 can can burn up in a output short please check.
Good luck
Are you sure ?
Check the service manual I posted and have a look at the last pages for info on the SAP pinout.
If they are faulty they can be replaced with SAP08, Sap10, Sap16 and of course with the new STD03N/P replacement.
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Neither channel has died well the PY's have died in both channels but it still plays sound from both channels but I will check these too.
Yea that's my thoughts I don't want to spent too much fixing it, but if I don't It will make a nice donor chassis and maybe able to re use the input and tone boards?
That looks like a great option and one I will probably go for it seems as I don't trust eBay for any of they SAP15's on there. Maybe worth buying a few extra aswell?
Thank you I will check all those out and thank you for the schematic!
Yes I believe they are dead from my testing they have a dead short, always wandered why it sounded underpowered so must have always just been working of the NY's?
The SAP transistors failing is quite a common thing in these amps - poor heatsinking and the onboard emitter resistor was quite fragile. The STD devices are the same device as the SAP, but without the onboard emitter resistor.
Nice idea Sanken, but flawed implementation. Probably why they are EOL'ing them completely now.
Nice idea Sanken, but flawed implementation. Probably why they are EOL'ing them completely now.
When the outputs fail they go short circuit and the input protection fuses blow.
The data sheet for the SAP15N can be reviewed.
SAP15N Datasheet(PDF) - Sanken electric
Just ensure your not measuring across the internal low value emitter resistor.
The data sheet for the SAP15N can be reviewed.
SAP15N Datasheet(PDF) - Sanken electric
Just ensure your not measuring across the internal low value emitter resistor.
