DFW Electronic Audio Repairs: AKer Footfungus is excellent!

[tensleep]

I have been looking at a stack of projects for far too long, with only a few rotation-worthy pieces of gear. So, upon other AKer's recommendations, I sought out Footfungus here on AudioKarma. I brought him Mitsubishi DA-P10/DA-A10 that had issues. The left channel quit altogether and the magic-in-a-can that is DeOxit was out of it's league. I was tired of looking at another boat anchor and had purchased this pair to go with a pair of Bozak Symphonies that I have owned/been working on for a couple of years.

Well, I got the pair back last night, along with a Rotel RA-870BX. The left channel had quit on it as well. My son had been using this integrated unit to drive a pair of EV Sentry 100a Studio Monitors - the pairing was excellent, until the channel gave up the ghost.

I think 5-6 weeks elapsed from when I dropped them off to hooking them back up here at my place. The Symphonies are remarkable, and the big Mitsubishi amp really hooks up the 4-12 woofers. Next up, refresh the crossovers and install 8 more tweeters to complete the vertical arrays.

The Rotel is driving my JBL 4410 Studio Monitors - truly, they have never sounded better. Unfortunately, they are not in the best space, as I am space constrained. I will see if I can remedy that somehow.

Anyway, Mr. Fungus (not sure about the ettiquette of sharing names - too many anonymous meetings, IYKWIM) did the following work for the following prices. Even with what I spent acquiring the gear added in, I don't think it is possible to touch the quality or the fidelity of these pieces at today's prices.

 

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The Rotel RA-870BX had a bad regulator and a failed op-amp in the phono section. There were some bad resistors and caps in the regulator section. The regulator section runs very hot. I replaced the TO-126 regulator transistors with bigger TO-220s. I recapped the phono and regulator board and the preamp section while troubleshooting. I also replaced 4 small caps in the amp section and set the bias. It should sound better now that the regulator caps are new and the bias is set proper (it was low, around 3.5mv instead of 5mv).


This is what was put in:

RA-870BX

KSC2690AYSTSTU 1

2SA1837 2 2SC4793 2

1N5248b 2

330 ohms 1/4w 1

220uf 25v PW 5

1000uf 16v FR 1

470uf 10v PW 1

2.7k 1/4w 2

100uf 35v FW 6

MOS1/2CT52R331J 4

4.7uf 35v Silmic 2

2200uf 25v FC 2

NE5534AP 2

 

[tensleep]

For the DA-P10 the only failure was one of the green bug relays. I rebuilt the power supply - new caps, transistors and diodes and cleaned up the glue. For the line stage section I recapped, replaced the Zener diodes, and replaced the input diff pairs and cascode transistors. For the phono stage, I recapped it and replaced the input diff pairs and current source (the leads on the original were black). The controls have been cleaned.


This is what was put in:

DA-P10

4.7uf 50v PM 4

47uf 16v ES 2

4.7uf 50v ES 4

1uf 50v ES 2

22uf 25v KL 2

20k ohm 2

470uf 63v HE 3

1000uf 63v HE 1

10uf 35v ES 2

2.2uf 50v PM 2

2.2uf 50v ES 2

220uf 25v PW 4

100uf 63v PW 12

10uf 50v PW 6

33uf 25v KL 2

Relay 2

470uf 10v FG 2

1uf 50v FG 2

BZX55B8V2 4

2SA1837 2

2SC4793 2

KSC1845FTA 2

KSA992FBU 8

KSC1845EBU 4

47uf 35v UKL 1

BZX55B33 2

BZX55B20 2

47uf 25v UES 2

 

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The DA-A10 was working ok. I replaced all the electrolytic caps, Zener diodes, 4 fusible resistors in the power supply, and the 2 MV-13 diodes. The output relays were changed, and the main power caps were replaced with 2 pairs of 10000uf 63v computer grade caps. I set the bias to 100ma, taking advantage of the massive heatsinks.


This is what was put in it:


DA-A10DC

470uf 100v PW 2

2200uf 10v PW 2

3.3uf 200v TVX 2

SZR-LY2-1P-DC24 2

22uf 63v PW 1

10uf 50v PW 1

220uf 25v PW 6

10uf 16v KL 1

1N914 4

1n5250b 2

1n5242b 2

330 ohms 1/2w 2

220 ohms 1/2w 2

ALS30A103DE063 4

M5 Screws 4

Loop Terminals 8


I wasn't able to find a good replacement on the power switch at Mouser. I was going to check if Tanners has one next time I'm there.


Total damage was $550:


$225 for the DA-A10

$200 for the DA-A10

$125 for the RA-870BX

 

[tensleep]

Great rates, great service, great communication. I can recommend his work.

 

[acapulcomike]

Great rates, great service, great communication. I can recommend his work.

Hi, I live in the Dallas area I need some service On Marantz I would like call this "footfungus" person I've looked on the web can't find any info. if could give phone # or email would be great.

Have good day; Michael