Sad Expo XX
- Thread starter cromodora
- Start date
cromodora
foshfishfie
Thanks for the input Rob,
It looks like one channel has blown and bodged with parts at hand (only one TO3 marked 2N3055 while the other five in Expo code. Also a few smaller devices and large tolerance resistors).
I'd like to get both channels symmetrical parts wise.
Exposure label their boards with partnos or values which is a big help.
Think I'll put in MJE15030/31 for the (presumably) driver pair and MJ15022/23 for the outputs.
It looks like one channel has blown and bodged with parts at hand (only one TO3 marked 2N3055 while the other five in Expo code. Also a few smaller devices and large tolerance resistors).
I'd like to get both channels symmetrical parts wise.
Exposure label their boards with partnos or values which is a big help.
Think I'll put in MJE15030/31 for the (presumably) driver pair and MJ15022/23 for the outputs.
cromodora
foshfishfie
Local Yahoo auction.
Won it for equivalent of 30UKP a few days ago.
A forgotten dead unit after an incomplete bodged repair on a blown channel.
Am trying to repair.
Sent email yesterday (Sunday) to Exposure service and guess what?
Tony Brady himself replied on the same day at that!
Can't compliment the man enough. Prompt and helpful.
The TO3 transistor pair (out of six in total) which I assumed were the drivers were actually part of the power amp regulator stage.
Values and parts on the Exposure board remind me of Naim and NCC200 bits.
Won it for equivalent of 30UKP a few days ago.
A forgotten dead unit after an incomplete bodged repair on a blown channel.
Am trying to repair.
Sent email yesterday (Sunday) to Exposure service and guess what?
Tony Brady himself replied on the same day at that!
Can't compliment the man enough. Prompt and helpful.
The TO3 transistor pair (out of six in total) which I assumed were the drivers were actually part of the power amp regulator stage.
Values and parts on the Exposure board remind me of Naim and NCC200 bits.
hifienthusiast
Vintage by heart
Tony Brady is a really helpful chap. He helped me to repair an Exposure pre amp once.
Good luck to your repair.
cromodora
foshfishfie
The 6 TO-3 transistors on the heatsink.
I have been told that the devices labelled EXP8P/N are for the power supply regulation. The EXP001P/N are the output devices. You can use the same 3 PNPs and 3 NPNs TO-3 devices. Motorola MJ15003/4 transistors are suitable substitutes.
I have ordered the relatively newer MJ15022/3 for my XX. They are reportedly better sounding.
However they are slightly faster so there's a risk of oscillation. Then I will have to turn them into fashionably techy earstuds, bodypiercing jewelry or brooches, sell them, and get proper 15003/4s.
P.S. I have a nagging feeling that maybe I should get a different pair for the regulator TO-3 transistors (EXP8N/P) for cost or performance reason.
Amp repair tips.
I have been told that the devices labelled EXP8P/N are for the power supply regulation. The EXP001P/N are the output devices. You can use the same 3 PNPs and 3 NPNs TO-3 devices. Motorola MJ15003/4 transistors are suitable substitutes.
I have ordered the relatively newer MJ15022/3 for my XX. They are reportedly better sounding.
However they are slightly faster so there's a risk of oscillation. Then I will have to turn them into fashionably techy earstuds, bodypiercing jewelry or brooches, sell them, and get proper 15003/4s.
P.S. I have a nagging feeling that maybe I should get a different pair for the regulator TO-3 transistors (EXP8N/P) for cost or performance reason.
Amp repair tips.
cromodora
foshfishfie
Hi Ron,
My experience with the XX was also covered in this thread..
The amp is working swimmingly now. I can't say whether its working as well as it should cause I've not heard a proper XX before this one. I can only compare it to a 32.5/Hicap/140 I have at hand. The expo is as musically satisfying, fuller bodied but with slightly less grip on my Castle Chesters. Still running in the new bits but am getting distracted with new projects.
If I had to do it again I will try the newer MJ21193/4 output transistors. I'll be getting some tighter fitting bananas for the speaker wires so they don't come loose and short the thing.
I'll be happy to help if you have any questions.
My experience with the XX was also covered in this thread..
The amp is working swimmingly now. I can't say whether its working as well as it should cause I've not heard a proper XX before this one. I can only compare it to a 32.5/Hicap/140 I have at hand. The expo is as musically satisfying, fuller bodied but with slightly less grip on my Castle Chesters. Still running in the new bits but am getting distracted with new projects.
If I had to do it again I will try the newer MJ21193/4 output transistors. I'll be getting some tighter fitting bananas for the speaker wires so they don't come loose and short the thing.
I'll be happy to help if you have any questions.
Hi,
1 of the capacitors has exploded near the power supply regulators and also resistors have blackened near the output transistors which will require changing.
A few questions before I get into replacing anything:
Did you find a suitable substitute for the EXP8N/EXP8P power supply regulators?
The original EXP001N/EXP001P output capacitors were changed to what equivalents?
Regards
1 of the capacitors has exploded near the power supply regulators and also resistors have blackened near the output transistors which will require changing.
A few questions before I get into replacing anything:
Did you find a suitable substitute for the EXP8N/EXP8P power supply regulators?
The original EXP001N/EXP001P output capacitors were changed to what equivalents?
Regards
cromodora
foshfishfie
I'm told you can use the same TO-3 transistors for the EXP8P/Ns as those for the EXP001N/Ps. However, I re-used the original EXP8N/P after finding them ok.
The EXP001N/P equivalent are the old Motorola MJ15003/4 now made by On semi. I took a chance and fitted the newer MJ150022/3 with no problems.
The EXP001N/P equivalent are the old Motorola MJ15003/4 now made by On semi. I took a chance and fitted the newer MJ150022/3 with no problems.