• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

LTig

Master Contributor
Forum Donor
Joined
Feb 27, 2019
Messages
5,760
Likes
9,442
Location
Europe
Marantz 2226 weekend project for my friend who has been buying too many basket cases...

This is Marantz stupidity at its finest. The input selector and phono stage PCB is inverted, sitting right under the ventilated grille. 45 years worth of dust and dirt and clearly a drink or two.
Reminds me of my first serious integrated amplifier, a Kenwood KA80 I had bought in 1983. The whole PCB including the STK power amp chips was upside down and the holes for ventilation were not sufficiently large so it got hotter than I'd liked. After 2 fixes (replaced a small cap) I sold it around 1989. Luckily the owner still uses it today, without any further failures in its 39th year ...
 

Burning Sounds

Addicted to Fun and Learning
Joined
Dec 22, 2016
Messages
523
Likes
883
Location
Co. Durham, UK
IMG_20211015_103711.jpg

Some new electrolytics on a Beard P100.
 

Pablo27

Member
Joined
Jul 11, 2022
Messages
61
Likes
61
17 x acoustic panels..what a job! Completed and mounted now, thankfully. Just a few bass traps to complete and I'm done.
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,273
Location
Gold Coast, Queensland, Australia

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,273
Location
Gold Coast, Queensland, Australia
New 2N3055s for the power amp....

Are you 100% sure they are genuine? They look a bit 'suspect' to me.

And interesting mounting- is there an insulating washer and nylon sleeved washer under the H/S or a PCB?
 

Berwhale

Major Contributor
Forum Donor
Joined
Aug 29, 2019
Messages
3,933
Likes
4,922
Location
UK
My Onkyo TX-NR609 keeps dropping the sound from my TV. Going to attempt BGA reflow on the DTS chip...

Onkyo TX-NR609- (Small).jpg


If it doesn't work, i'll buy a Denon AVR-X1700H which is currently available for £464 in the UK from Peter Tyson via eBay with 20% discount (code 'DEAL20')... https://www.ebay.co.uk/itm/225112590778

*** Update ***

Speaker indicators are back on and there's sound coming out :)

IMG_20220924_151434 (Small).jpg


I don't know if this will be a 'permanent' fix. I was only able to get the DTS chip up to 150C (300F) with my little hot air blower (which I guess is designed for heat shrink). My understanding is that I need to get the chip up to 220C (430F) to actually melt the solder.

*** Update 2 ***

As suspected, it's died again :( I'm going to order a more powerful heat gun and the X1700H.
 
Last edited:

Burning Sounds

Addicted to Fun and Learning
Joined
Dec 22, 2016
Messages
523
Likes
883
Location
Co. Durham, UK
I like your Civil War era screwdriver. :)
Heh, heh, yeah probably English civil war
:D
Actually, it's not a screwdriver, if you look closely you'll see it has a forked tip, perfect for lifting resistors when desoldering etc. IIRC the broken end had a pointed tip. It was amongst a load of old but useful tools I got when the daughter of an ex-US Navy guy was clearing out his garage many years ago. Included in the "junk" was a Leica, a Bolex and a fair number of Eimac transmitter valves, power and output transformers which I sold to David Manley who at that time still had VTL David had donated very generously to a community radio station where I had a programme. I still have a Garrott Brothers (the real deal) P77 cartridge that he gave me.
 

Burning Sounds

Addicted to Fun and Learning
Joined
Dec 22, 2016
Messages
523
Likes
883
Location
Co. Durham, UK
Are you 100% sure they are genuine? They look a bit 'suspect' to me.

And interesting mounting- is there an insulating washer and nylon sleeved washer under the H/S or a PCB?
I'm curious as to what makes you think they might be "suspect" - they were purchased from Mouser, so highly unlikely. They are mounted using a Keystone mounting kit. The heatsink is fixed to another finned heatsink that exits the back of the jukebox. The amp produces about 55wpc. Only 1 of the 4 original Motorola transistors was faulty and 98% of the jukebox is original including most of the electronics (electrolytics are Rubycons), speakers, relays etc.

Rock-Olas are particularly robust (Bel-Amis probably sounded better), and always made a big play in their advertising on their reliability. A broken down jukebox was making no money for the bar owner, so sound quality was less of a concern to them than reliability. Servicemen must have loved these 1974 454s - everything contained on modular boards. Rock-Ola is the only jukebox company still going, although made in California now instead of Chicago and owned by an Englishman from Leeds. If you have the time Rock-Ola's history is fascinating - Chicago gangsters, jail time, and a clever innovator.
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,273
Location
Gold Coast, Queensland, Australia
I'm curious as to what makes you think they might be "suspect" - they were purchased from Mouser, so highly unlikely.

Well, fair enough I guess. It does show how QC has gone out the window with device markings. There was once a time when Motorola would reject T03s where the labelling wasn't centred, square, or not perfectly clear.

Most of the Chinese copies of 2N3055 have imperfect lettering that rubs off easily.

Yeah, I like your lever tool. Sometimes it's the tools we make/find/scavenge that become the most used tools in our arsenal.
 
Last edited:

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,273
Location
Gold Coast, Queensland, Australia
If you have the time Rock-Ola's history is fascinating - Chicago gangsters, jail time, and a clever innovator.

What a wonderful read. Thank you. Dug around on the Chicago Museum Site, I've always had a fascination with Chicago Flexible Shaft Co and their engineer Ivar Jepson who created the legacy of the Sunbeam Mixmaster.
 

AnalogSteph

Major Contributor
Joined
Nov 6, 2018
Messages
3,334
Likes
3,278
Location
.de
*** Update 2 ***

As suspected, it's died again :( I'm going to order a more powerful heat gun and the X1700H.
To my understanding, the DSP chip has issues akin to "nVidia Bumpgate". You'd need a whole new DSP chip of the fixed Dxxx revision for a permanent fix.
Reminds me of my first serious integrated amplifier, a Kenwood KA80 I had bought in 1983. The whole PCB including the STK power amp chips was upside down and the holes for ventilation were not sufficiently large so it got hotter than I'd liked. After 2 fixes (replaced a small cap) I sold it around 1989. Luckily the owner still uses it today, without any further failures in its 39th year ...
These amps were notorious for that. I still have the companion KT-80 tuner on my nightstand, which only has minor issues in comparison (the output coupling caps are likely to be dead dead, the power supply section for lighting is a bit silly, and I sort of doubt it would pass modern IEC Class II guidelines).
 

Berwhale

Major Contributor
Forum Donor
Joined
Aug 29, 2019
Messages
3,933
Likes
4,922
Location
UK
To my understanding, the DSP chip has issues akin to "nVidia Bumpgate". You'd need a whole new DSP chip of the fixed Dxxx revision for a permanent fix.

I had to throw away one of the 1st Dell XPS13 laptops because of that issue. I had two motherboards fail with the same problem. The second board failed after a year even though i'd fitted a custom copper heat spreader between GFX chip and heatpipe. The laptop was given to me by Dell as an 'eval' unit, so it didn't cost me anything apart from my time and the cost of the second motherboard (and copper shim).

With respect to the DTS chip, I heated up tonight with my new heat gun. I had to get the tip of the gun really close to the chip to get it hot enough. In fact, I thought I hadn't got it hot enough until I touched the chip with the tip of the gun and moved it :( Oh well, the X1700H should arrive on Tuesday.
 

sergeauckland

Major Contributor
Forum Donor
Joined
Mar 16, 2016
Messages
3,440
Likes
9,100
Location
Suffolk UK
When I was at school, I built a number of Mullard 5-10s for myself and friends. We're going into the winter, and I know I'm going to be bored, so I fancied recovering my lost youth (yeah, right!) by building one again.

So, today I bought this, sold as a GEC 912 amplifier, which was GEC's version of the 510. Same EL84 valves, different phase splitter, but same output transformer spec, so I can rebuild this as either a 5-10, or perhaps keep the circuit as a 912, but strip out all the tone controls and preamp and configure it as a pure power amp. Looking at the two circuit diagrams, a 912 as a pure power amp should have lower noise and distortion than the 5-10 as it doesn't use an EF86 as the first valve, but there probably won't be a lot in it.

It looks like a fairly decent home-build, but as it's likely to be getting on 60 years old, I'll first make sure it's safe before putting any power on it. At least whoever built it, did properly earth the case...

It'll be interesting to see how many of the 60 year old electrolytics are still usable. That'll make an interesting comment on those people who recap their amps because they're 10 years old...

Problem is that when I've finished the rebuild, I have no use for amp! Just nice to have. By the way, I've also bought a Quad II amp to restore as well, haven't received it yet, and no, I don't have a use for that either. My kids will love me when I'm dead and they have to clear out all this stuff.

912 front.jpg


912 top.jpg
912 bottom.jpg
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,579
Likes
38,273
Location
Gold Coast, Queensland, Australia
I love it!

Realistically, I say, we take off and nuke the entire site from orbit. It's the only way to be sure...
 
OP
pma

pma

Major Contributor
Joined
Feb 23, 2019
Messages
4,591
Likes
10,727
Location
Prague
This is my SE to balanced converter, with 1 x OPA627 and 2 x ADA4898

SE-to-BAL.JPG


And it measures like this

E1DA_SYM2-ADA4898.png


In fact the result is better than the direct DAC-ADC loop, because those ADA4898 can drive low impedance loads (like E1DA input) better than the LME49720 of the DAC output.
 
Top Bottom