Hello,
I'm about to buy a used broken Marantz PM-80 for 30 euros.
Seller says that there is no sound and relays don't click. After reading about it here in the forums I think it could be TA7317P or some resistors/capacitors around it. Or infamous stk-3102-iv. I found these parts on AliExpress just don't know if its worth it ordering from there or there are some in Greek.
But it's not that important right now.
I would like to keep the amplifier and thought about adding 1 or 2 fans for the heatsinks and overall circulation, add a heatsink for STK chip and source some airflow over it, would it improve the longevity of the amplifier besides requiring recapping from time to time?
Also, how about resoldering the whole board? I've read that PM-80 had some trouble with bad solder joints that would degrade over time would redoing the whole board improve something?
Besides these "Modifications".
What could also cause relays not click? More insight for what to look for is greatly appreciated.
And also coming from NAD 7240PE will this amplifier (PM-80) improve the sound quality and how does it sound overall?
I'm about to buy a used broken Marantz PM-80 for 30 euros.
Seller says that there is no sound and relays don't click. After reading about it here in the forums I think it could be TA7317P or some resistors/capacitors around it. Or infamous stk-3102-iv. I found these parts on AliExpress just don't know if its worth it ordering from there or there are some in Greek.
But it's not that important right now.
I would like to keep the amplifier and thought about adding 1 or 2 fans for the heatsinks and overall circulation, add a heatsink for STK chip and source some airflow over it, would it improve the longevity of the amplifier besides requiring recapping from time to time?
Also, how about resoldering the whole board? I've read that PM-80 had some trouble with bad solder joints that would degrade over time would redoing the whole board improve something?
Besides these "Modifications".
What could also cause relays not click? More insight for what to look for is greatly appreciated.
And also coming from NAD 7240PE will this amplifier (PM-80) improve the sound quality and how does it sound overall?
For 30 euros I would buy it as is, regardless, the transformer alone would be worth it.
The most likely fault is a defect STK-module leading to too high DC levels on the output and making the protection (the TA7317) do its work. But keep in mind more parts may have failed.
I would not buy parts off eBay, but I'm pretty sure someone designed a replacement for the STK-3102 and a search on this forum should find it.
Obviously some experience, or help from an experienced person is required. And knowledge on how to work safely on mains powered equipment.
I don't know NAD as I have gone from Marantz PM-40SE to PM-80SE to PM-15S2LE. If you like the Marantz sound, then you'll be fine.
The most likely fault is a defect STK-module leading to too high DC levels on the output and making the protection (the TA7317) do its work. But keep in mind more parts may have failed.
I would not buy parts off eBay, but I'm pretty sure someone designed a replacement for the STK-3102 and a search on this forum should find it.
Obviously some experience, or help from an experienced person is required. And knowledge on how to work safely on mains powered equipment.
I don't know NAD as I have gone from Marantz PM-40SE to PM-80SE to PM-15S2LE. If you like the Marantz sound, then you'll be fine.
My first repair was with the fake STK3102 which failed couple of years later. It was made with only SOT-23 transistors, so that's not that strange.
David's design looks to be way more sensible. I never used it, though.
In 2012 I bought the PM-15S2LE, keeping the PM-80SE, intending to repair it one day. But years later I sold the PM-80SE as defective, still got € 150 for it IIRC.
I'm not 100% sure, but I believe it doesn't really matter if you have the III- or IV-version of the module.
David's design looks to be way more sensible. I never used it, though.
In 2012 I bought the PM-15S2LE, keeping the PM-80SE, intending to repair it one day. But years later I sold the PM-80SE as defective, still got € 150 for it IIRC.
I'm not 100% sure, but I believe it doesn't really matter if you have the III- or IV-version of the module.
Then you know the drill - voltages on rails, voltages on outputs before relays voltages stepping backwards from the outputs...
I repaired the LUXMAN L 435 amplifier using the module you designed and tested it, tested it at an output power with a resistive load of 100 W at 8 Ohms at 20 kHz. I listened for several hours and my impressions of the sound of the amplifier are purely positive. The quiescent current is adjusted and remains excellent! If anyone needs a clone of STK3xxx on SMD developed by David on FR4, the second layer of foil of the board is preserved, then please contact me in a personal conversation or for advice.