Ok JoolsB, my mistake. Canadian English terminology and UK are a little different.
I shall put them back in place tonight and see what happens. This will likely bring me back to where I was when started.
Cheers
Ben
I shall put them back in place tonight and see what happens. This will likely bring me back to where I was when started.
Cheers
Ben
Ok Gents, last night I "replaced" the OTs back into their positions, but switched them around, and replaced the fuses. It works. Really not sure why it didn't work in the first place. I am puzzled.
I do thank you JoolsB and Andrew in guiding me through this.
Ben
I do thank you JoolsB and Andrew in guiding me through this.
Ben
Well... something did get damaged. Played some music through the Cyrus 2 and noticed that the left channel has very noticeable distortion. As soon as I turn up the volume just around 2, the woofer pulsates in and out as if I would be playing it 5. The OT voltage is constant for all 4. Therefore it must be elsewhere on the left channel branch. When playing it at low volume (below 1), can't really notice, but turning it up just a bit and wham, there's the distortion and excessive cone movement.
Any ideas?
Thanks!
Any ideas?
Thanks!
Swap your speakers to make sure it's not a speaker problem. Then, swap your your inputs to make sure it's not a problem with your CD player (or whatever your music source is).
Quiescent current
Hi
I'm new to this but here's a weird one for you. Just replaced outputs (BUV48a motorola) and drivers (MJE243/253) on blown left channel. Having a lot of trouble getting quiescent where I want it. Right channel stablises to 15mV in about 30 seconds but left takes about 5 mins to reach 11mV (if I reduce resistor value by 10R it settles at 20mV). The weird thing is if you blast some sound out for a bit to heat it up then retest... Right is still within tolerance at 10mV and quickly resettles at 15mV but left has dropped to 3mV and again takes ages to go back up and settle.
Anyone help?? (and yes I've checked and rechecked every pre-driver and every emitter resistor).
Hi
I'm new to this but here's a weird one for you. Just replaced outputs (BUV48a motorola) and drivers (MJE243/253) on blown left channel. Having a lot of trouble getting quiescent where I want it. Right channel stablises to 15mV in about 30 seconds but left takes about 5 mins to reach 11mV (if I reduce resistor value by 10R it settles at 20mV). The weird thing is if you blast some sound out for a bit to heat it up then retest... Right is still within tolerance at 10mV and quickly resettles at 15mV but left has dropped to 3mV and again takes ages to go back up and settle.
Anyone help?? (and yes I've checked and rechecked every pre-driver and every emitter resistor).
JoolsB,
I did swapped the speaker connections and source inputs. The same affect was reproduced on the other speaker, no change with swapped inputs. I even connected the speakers to another amp and are working fine.
For reference: I'm looking at an old service invoice from a similar stituation with this amp from a few years ago. They replaced:
2 OT (TP-77)
2 drive transistors (JE 243, JE 253)
2 caps (22 uf / 50V)
1 fuse (2.5A / 125V) - no clue where this fuse is located
Perhaps I should check the drive trans or 22uf caps?
I did swapped the speaker connections and source inputs. The same affect was reproduced on the other speaker, no change with swapped inputs. I even connected the speakers to another amp and are working fine.
For reference: I'm looking at an old service invoice from a similar stituation with this amp from a few years ago. They replaced:
2 OT (TP-77)
2 drive transistors (JE 243, JE 253)
2 caps (22 uf / 50V)
1 fuse (2.5A / 125V) - no clue where this fuse is located
Perhaps I should check the drive trans or 22uf caps?
you should swap one item at a time.benlalonde said:
Otherwise the same fault could appear in the same channel and mislead you.
Hi Ben
I'd test as many of the output stage componenets as you can with your multi-meter.
There's a Cyrus 1 schematic for one channel here: http://www.tcaas.btinternet.co.uk/cyrus1pwr.gif
If you don't have a scope, one approach would be to start swapping components. It's a bit fiddly, but you have one side you know works and one that doesn't.
E.g. If you take the OT's you know are ok, replace those you suspect with them and the problem goes away, you've found the fault.
I don't think you'll be able to get replacement PT77's. I couldn't get any, so I replaced them with TIP41C's from e-bay.
MJE243/253
http://cgi.ebay.co.uk/ws/eBayISAPI....em=170231323239
http://cgi.ebay.co.uk/ws/eBayISAPI....em=170231323452
TIP41C
http://cgi.ebay.co.uk/ws/eBayISAPI....em=230325875203
I'd test as many of the output stage componenets as you can with your multi-meter.
There's a Cyrus 1 schematic for one channel here: http://www.tcaas.btinternet.co.uk/cyrus1pwr.gif
If you don't have a scope, one approach would be to start swapping components. It's a bit fiddly, but you have one side you know works and one that doesn't.
E.g. If you take the OT's you know are ok, replace those you suspect with them and the problem goes away, you've found the fault.
I don't think you'll be able to get replacement PT77's. I couldn't get any, so I replaced them with TIP41C's from e-bay.
MJE243/253
http://cgi.ebay.co.uk/ws/eBayISAPI....em=170231323239
http://cgi.ebay.co.uk/ws/eBayISAPI....em=170231323452
TIP41C
http://cgi.ebay.co.uk/ws/eBayISAPI....em=230325875203
Hi canfixit
I've seen similar wierdness with electrolytic capacitors degrading. Might be worth checking..
I've seen similar wierdness with electrolytic capacitors degrading. Might be worth checking..
...I meant from Andrews reply:
"you should swap one item at a time.
Otherwise the same fault could appear in the same channel and mislead you."
"you should swap one item at a time.
Otherwise the same fault could appear in the same channel and mislead you."
Names Tim by the way...just to chip in what's with the TIP41C I thought the recommended replacement is BUV48A which is also available on eBay.
Re my weird fluctuating quiescent I've changed the 22uF caps you're talking about as they go between collector and emitter of the bias transistor but made no difference. Can't see any other electrolytics in the power amp that are likely to affect it.
Tim
Re my weird fluctuating quiescent I've changed the 22uF caps you're talking about as they go between collector and emitter of the bias transistor but made no difference. Can't see any other electrolytics in the power amp that are likely to affect it.
Tim
Hi Tim
You're right about the BUV48A's I think - I was thinking of Cyrus 1, not Cyrus 2. I replaced a "1" with TIP41C's and they work fine.
No idea about the quiescent problem then I'm afraid.
You're right about the BUV48A's I think - I was thinking of Cyrus 1, not Cyrus 2. I replaced a "1" with TIP41C's and they work fine.
No idea about the quiescent problem then I'm afraid.
Problems Trouble shooting my cyrus two ver 7 amp
javascript:smilie('🙂')Hi Guys
Ive Had a Cyrus Two + PSX for a good few years now, but have just started getting problems with fuses blowing in psx and Left channel dropped in volume on Cyrus Two. After an investigation of the psx found to be faulty Caps, 15000u times 4, they had started to buldge.
Ive replaced these, no more blown psx fuses. then turned to amp. As a matter of course replaced the two 10000u caps, and then started to investigate channel problems.
I injected a signal from funtion gen at 1K and attached the scope to three sets of test points on the board. Not having a schematic, wasnt really sure what to expect. from input to output, I got readings of stage one 4ma stage two 40ma output stage 400 ma on the right channel, which is a factor of 10 that seemed fine.
When I tested Left channel all was the same until I got to output stage then the readings
on the scope stayed at 40ma, which I concluded the problem must be a transitor in this stage.
I proceded to check the base of each transistor and got readings of 40ma. then I could have kicked myself, whilst watching the scope,javascript:smilie('
') I SLIPPED OF THE BASE MAKING CONTACT WITH BASE AND COLLECTOR you can guess what happened. I blew a fuse and with it a JE253 and along with it a PT77 output transistor, 3 others remain ok.
I Know clumsy great nana. I also found that aJE243 had some rather strange readings, I suspect that was the problem in the first place now ive just compounded it.
My Question is this. I cant find PT77 anywhere now so do I need to replace all output transistors with new equivalents to keep the balance, or just replace two, note two per channel on this model.
Also should I replace all 4 JE243 andJE253s for new equivalents. and what would they be now.
PS one other problem, I have replaced the two 470u 50v caps that follow regs, because my phono stage is getting a hum, but still has hum when nothing is connected to phono, but gets less when something is plugged in. what else would be causing this, im thinking these are smoothing caps for dedicated phono when using psx, and must be filter caps else where but again without a schematic im a bit stuck.
I did try to purchase from Cyrus, but they werent very accomodating, apart from if I wanted to take the amp to them at a steep price. These amps are now very old, and they have moved on from them so why they cant release the schematic now beats me. I think they still want the monopoly on repairs.
Many thanks for your help, I still cant believe I could be so clumsy.
javascript:smilie('
')
regards
Mark.javascript:smilie('
')
javascript:smilie('🙂')Hi Guys
Ive Had a Cyrus Two + PSX for a good few years now, but have just started getting problems with fuses blowing in psx and Left channel dropped in volume on Cyrus Two. After an investigation of the psx found to be faulty Caps, 15000u times 4, they had started to buldge.
Ive replaced these, no more blown psx fuses. then turned to amp. As a matter of course replaced the two 10000u caps, and then started to investigate channel problems.
I injected a signal from funtion gen at 1K and attached the scope to three sets of test points on the board. Not having a schematic, wasnt really sure what to expect. from input to output, I got readings of stage one 4ma stage two 40ma output stage 400 ma on the right channel, which is a factor of 10 that seemed fine.
When I tested Left channel all was the same until I got to output stage then the readings
on the scope stayed at 40ma, which I concluded the problem must be a transitor in this stage.
I proceded to check the base of each transistor and got readings of 40ma. then I could have kicked myself, whilst watching the scope,javascript:smilie('
') I SLIPPED OF THE BASE MAKING CONTACT WITH BASE AND COLLECTOR you can guess what happened. I blew a fuse and with it a JE253 and along with it a PT77 output transistor, 3 others remain ok.I Know clumsy great nana. I also found that aJE243 had some rather strange readings, I suspect that was the problem in the first place now ive just compounded it.
My Question is this. I cant find PT77 anywhere now so do I need to replace all output transistors with new equivalents to keep the balance, or just replace two, note two per channel on this model.
Also should I replace all 4 JE243 andJE253s for new equivalents. and what would they be now.
PS one other problem, I have replaced the two 470u 50v caps that follow regs, because my phono stage is getting a hum, but still has hum when nothing is connected to phono, but gets less when something is plugged in. what else would be causing this, im thinking these are smoothing caps for dedicated phono when using psx, and must be filter caps else where but again without a schematic im a bit stuck.
I did try to purchase from Cyrus, but they werent very accomodating, apart from if I wanted to take the amp to them at a steep price. These amps are now very old, and they have moved on from them so why they cant release the schematic now beats me. I think they still want the monopoly on repairs.
Many thanks for your help, I still cant believe I could be so clumsy.
javascript:smilie('
')regards
Mark.javascript:smilie('
')Hi Mark
Yep - I've done the clumsy thing before too.
For the Cyrus 2, I think the commonly used PT77 alternative is the BUV48.
The JE243 & JE253 now seem to be called MJE243 & MJE253.
You can get all of these devices easily from Ebay & there's no minimum qty.
Personally, I'd just change one channel & see if you can tell any difference, then change the other if there is.
As for the hum - I'd try to find out if it's mains (50Hz) to give you some clues.
Yep - I've done the clumsy thing before too.
For the Cyrus 2, I think the commonly used PT77 alternative is the BUV48.
The JE243 & JE253 now seem to be called MJE243 & MJE253.
You can get all of these devices easily from Ebay & there's no minimum qty.
Personally, I'd just change one channel & see if you can tell any difference, then change the other if there is.
As for the hum - I'd try to find out if it's mains (50Hz) to give you some clues.
Cyrus 2 schematic
Hi Mark
Please find link to Cyrus One service manual the second part of it is version 7 (metal case Cyrus One aka Cyrus 2 and almost identical schema). You may need to register first. Hope it helps. http://www.hifiengine.com/manuals/cyrus/one.shtml
You may not ever cure the hum by replacing parts in the amp, many many amps suffer from it. Check out IsoTek mains conditioning devices.
P.S. Some makes of BUV48a are better than others I found Motorola ones took a long time to stabilise compared to ST make, which I've seen more commonly used as replacements.
Tim
Hi Mark
Please find link to Cyrus One service manual the second part of it is version 7 (metal case Cyrus One aka Cyrus 2 and almost identical schema). You may need to register first. Hope it helps. http://www.hifiengine.com/manuals/cyrus/one.shtml
You may not ever cure the hum by replacing parts in the amp, many many amps suffer from it. Check out IsoTek mains conditioning devices.
P.S. Some makes of BUV48a are better than others I found Motorola ones took a long time to stabilise compared to ST make, which I've seen more commonly used as replacements.
Tim
Cyrus Two Replacement output transistors
javascript:smilie('🙂' )Many thanks for your kind advice guys. I will lookup ebay parts, and get them ordered. The amp has a lovely MM phono stage, and I will be glad to put it back into service witha new lease of life again.
I tried the link kindly provided by JoolsB but my web browser informs me the URL is not valid and cant be loaded, perhaps discontinued or maybe a type error.
I will test for 50HZ breakthru as soon as I can power up again.
Will keep you all informed with progress,
Keep the good work up guy's
Kind Regards
Mark. javascript:smilie('😀')
javascript:smilie('🙂' )Many thanks for your kind advice guys. I will lookup ebay parts, and get them ordered. The amp has a lovely MM phono stage, and I will be glad to put it back into service witha new lease of life again.
I tried the link kindly provided by JoolsB but my web browser informs me the URL is not valid and cant be loaded, perhaps discontinued or maybe a type error.
I will test for 50HZ breakthru as soon as I can power up again.
Will keep you all informed with progress,
Keep the good work up guy's
Kind Regards
Mark. javascript:smilie('😀')
Re: Cyrus Two Replacement output transistors
Great link by the way, Tim! It's interesting that they provide details of how to turn it into a mono amp. I know it's simple enough to do anyway but it's interesting that they expected some of their customers to need this facility.
Great link by the way, Tim! It's interesting that they provide details of how to turn it into a mono amp. I know it's simple enough to do anyway but it's interesting that they expected some of their customers to need this facility.
🙂 Hi all
Managed to get the service manual for Cyrus One it is very similar to Cyrus two, thanks to JoolsB, I found a problem with my browser, and the link www.hifiengine.com/manuals/cyrus/one.shtml 😀 DOES work, already a member so downloaded no problem thanks,
What a lovely service manual, very clearly and understandably written. Have now orded replacements for PT77s decided to replace all four with BUV48as and renew the MJE243 / 253 power transistors only £12 from ebay so why skimp. should arrive soon. With the manual, Im hoping to get to the bottom of this now, will let you know how I get on. Wonder why they have released Cyrus one but Not Cyrus two Service Manual.
Yes Sonusthree its interesting to note that you can use the amp as a mono block. I cant remember It Mentioning that in the instruction Manual tho, Even if it where on the lines of take it to your dealer and it can be set in this mode for you??
Just need to pick up another Cyrus Two to try that out.
I have just got hold of a book by Elektor Electronics, called Build your own High End Audio Equipment, and interestingly, One of the Pre-amp Designs in the book, uses the very same Opamps as in the Cyrus two for the phono stage, so that go to show quality parts used in this amp.
Opamps NE5532 + NE5534 among other alternatives where suggested.
Many thanks to all will let you know the progress,
Regards
Mark
Managed to get the service manual for Cyrus One it is very similar to Cyrus two, thanks to JoolsB, I found a problem with my browser, and the link www.hifiengine.com/manuals/cyrus/one.shtml 😀 DOES work, already a member so downloaded no problem thanks,
What a lovely service manual, very clearly and understandably written. Have now orded replacements for PT77s decided to replace all four with BUV48as and renew the MJE243 / 253 power transistors only £12 from ebay so why skimp. should arrive soon. With the manual, Im hoping to get to the bottom of this now, will let you know how I get on. Wonder why they have released Cyrus one but Not Cyrus two Service Manual.
Yes Sonusthree its interesting to note that you can use the amp as a mono block. I cant remember It Mentioning that in the instruction Manual tho, Even if it where on the lines of take it to your dealer and it can be set in this mode for you??
Just need to pick up another Cyrus Two to try that out.
I have just got hold of a book by Elektor Electronics, called Build your own High End Audio Equipment, and interestingly, One of the Pre-amp Designs in the book, uses the very same Opamps as in the Cyrus two for the phono stage, so that go to show quality parts used in this amp.
Opamps NE5532 + NE5534 among other alternatives where suggested.
Many thanks to all will let you know the progress,
Regards
Mark
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