atkelar | Restoration Project #34 - Revox A72x - Part 1 @atkelar | Uploaded April 2022 | Updated October 2024, 14 hours ago.
About half a year ago, Emil - an online friend from Germany - asked if I would be interested in saving a Revox A720 receiver/pre-amp from the scrap bin - it would need some TLC and repairs but would be "shipping only" otherwise. As I was looking for a pre-amp to connect with my turntable, I took up the offer right away! It did look interesting, even though I never heard from that brand much less that particular model before...
It was indeed in need of repair: some buttons were missing and both sliding pots were busted off... the 12kg of the unit had a lasting impact on them for sure!
Eventually, that model did grow on my however and I did my best to find a matching power amplifier to go with it... but when I found out that these things go for 500+ Euro a piece on e-bay, I did not hope for any affordable one; I certainly didn't expect a free one like the pre-amp... But then, an "untested" one appeared for just-barely-within painful-but-affordable range and I got it about a month ago: time to start that project!
In this episode, I cover the disassembly and recapping of both units; the assembly, adjustment overview and troubleshooting will be in the next one!
0:00 Intro - Presentation / Unpacking
1:35 Look Inside / Botches?
3:18 Broken Stuff / Disassembly
4:32 Transformer Mishap / Input PCB / Botch #2
6:08 Button Board / Switch Board
6:38 Tuning Matrix Disassembly
7:35 Wiring Loom Nastyness / Input PCB Refurbishment
9:00 Power Supply PCB
10:18 Tuning Knob Explanation / Manual Tuning Assembly
12:00 Preset Switches Disassembly / Button Cleaning / Relay Cleaning
13:55 Volume and Balance Potentiometer Repair
15:08 Wire Loom Repair / Tuning Meter Issue
16:39 A720 and Audio Output? Presenting the A722!
17:42 Smoked Amp?
18:24 Power Amp Stage Recapping and Potentiometer
19:37 Fresh Thermal Paste (after a good scrub!) / Speaker Relay Cleaning
20:40 DC Filter Caps / Cleaning Flux
21:37 To be continued...
Music:
My Train's A Comin'
Unicorn Heads
(YouTube Audio Library)
You can support me on Ko-Fi: ko-fi.com/atkelar
About half a year ago, Emil - an online friend from Germany - asked if I would be interested in saving a Revox A720 receiver/pre-amp from the scrap bin - it would need some TLC and repairs but would be "shipping only" otherwise. As I was looking for a pre-amp to connect with my turntable, I took up the offer right away! It did look interesting, even though I never heard from that brand much less that particular model before...
It was indeed in need of repair: some buttons were missing and both sliding pots were busted off... the 12kg of the unit had a lasting impact on them for sure!
Eventually, that model did grow on my however and I did my best to find a matching power amplifier to go with it... but when I found out that these things go for 500+ Euro a piece on e-bay, I did not hope for any affordable one; I certainly didn't expect a free one like the pre-amp... But then, an "untested" one appeared for just-barely-within painful-but-affordable range and I got it about a month ago: time to start that project!
In this episode, I cover the disassembly and recapping of both units; the assembly, adjustment overview and troubleshooting will be in the next one!
0:00 Intro - Presentation / Unpacking
1:35 Look Inside / Botches?
3:18 Broken Stuff / Disassembly
4:32 Transformer Mishap / Input PCB / Botch #2
6:08 Button Board / Switch Board
6:38 Tuning Matrix Disassembly
7:35 Wiring Loom Nastyness / Input PCB Refurbishment
9:00 Power Supply PCB
10:18 Tuning Knob Explanation / Manual Tuning Assembly
12:00 Preset Switches Disassembly / Button Cleaning / Relay Cleaning
13:55 Volume and Balance Potentiometer Repair
15:08 Wire Loom Repair / Tuning Meter Issue
16:39 A720 and Audio Output? Presenting the A722!
17:42 Smoked Amp?
18:24 Power Amp Stage Recapping and Potentiometer
19:37 Fresh Thermal Paste (after a good scrub!) / Speaker Relay Cleaning
20:40 DC Filter Caps / Cleaning Flux
21:37 To be continued...
Music:
My Train's A Comin'
Unicorn Heads
(YouTube Audio Library)
You can support me on Ko-Fi: ko-fi.com/atkelar
