Marantz SD 8020 - mission impossible?

paul_ral · Mar 26, 2012

Hi, I' m new on this forum and I' m a big fan of vintage Marantz from '80.
I found a SD 8020 2 speed compudeck, but isn't in a good condition. The owner told me that the cover has been lost, he sold some parts like transformer, tapehead, mic&line record level potentiometers, three switches from front panel and some knobs. He promised me new pictures of it, and ask arround 25$. I know it is a rare deck, it would be hard to find the missing parts, but i try. In the worst case i'll keep as a museum piece.
I'm waiting for your opinions and excuse for my English

ChrisMarantz · Mar 26, 2012

I think it's a cool deck and if you up for the long haul it would be cool to have a working model.

I have searched for as long as 2 years for hard to find parts or a donor unit.

Good Hunting!

paul_ral · Mar 27, 2012

Agree with you Chris. I downloaded the service manual and now i'm looking for missing parts. It consist of many boards and I suppose that some of them were sold with potentiometers and switches. I'm waiting for some pics from inside the deck. I think i can built the missing parts using other from the japanese decks (pots and switches).
This is a single picture from his announcement I have

paul_ral · Apr 26, 2012

The seller sent my some pictures of the deck and agreed to my offer: 40$ I think I can fix it. Wish me luck! I'll post more pictures when it arrives to me.

ChrisMarantz · Apr 27, 2012

Well you do have yourself a project there. It looks very complicated, any idea how many of these were made?

petehall347 · Apr 27, 2012

making me wonder why the parts are missing . maybe they were the working parts and what is left is faulty . or he just made more money selling the parts from a working unit . hard to say . maybe ask the seller .

paul_ral · Apr 28, 2012

I have no ideea how many 8020 were made and how many are still working. I put same question on the forum in my country and only one guy told me that he got one with problems. I found this page http://www.pdemara.com/ , very interesting, i think i found the answer to pete.
From mr. Paul DeMara's webpage:
"Unfortunately, over the years, the SD9000 and its little brother, the SD8000 proved to have an "Achilles' Heel". Both decks used a pair of optical sensors to generate reel turn count pulses for their onboard microprocessors. This microprocessor also interpreted lack of these pulses as a signal that the end of the cassette had been reached, and would send send an "all stop" command to the transport 1.5 seconds after pulse cessation. After 10 years or so, depending upon use, these optical sensors (also known as 'optocouplers') would weaken and fail. The symptom? After one to two seconds in any mode, Play, Rewind, or Fast Forward, the deck simply returns to the Stop mode. Over the course of 25 years, the failure percentage of these optocouplers approaches 100%. Worse than almost certain failure of these key components is the fact that the original replacement optocouplers are now no longer available, rendering these expensive cassette decks essentially useless."

paul_ral · May 3, 2012

So, today I picked up my little monster. I'm glad because the seller was found the cover lid, but sad in same time looking at the ruin inside. But I don't surrender! I made some pictures, i begin with outside.

The front panel is looking good, except the missing parts

I found some scratches arround the power switch

One screw is missing on the cassette compartment and the head was sold

two screws from VU-meter display and knobs are gone

And disaster continue: mic&line record level pots and switches from programming zone are missing too. Output level pot is damaged

Going to back, the volage selector isn't there

So this is the situation outside the deck, i'll continue presenting inside and i'll indicate places with problems in order to fix it. Any help is welcome, wish me luck.

ChrisMarantz · May 3, 2012

Did you look at the 2 that are for sale on eBay? Cheap price and they may be good as parts units

FAB1 · May 3, 2012

That article is part true and part false. You can replace the octocouplers. Mouser has the part it just needs slight modification to fit. Anyone who wants to throw their virtually useless Compudeck my way let me know..ha ha

paul_ral · May 3, 2012

Thanks. Yes, interesting, I think the prices will increase but for me is a little problem: distance between us. I bought a lot of parts for my Vento (Jetta3 in U.S. as you know) from vwvortex and shipping was more expensive than parts themselves. I found some parts în Germany, i'll make a list and negotiate with seller. Shipping from Germany to Romania is cheaper. These are the parts I need

paul_ral · May 4, 2012

First board is named computer assembly, code PK21. Here I found some troubles:
Few transistors were cut from the board. 5 are 2SC2634(S) and one is 2SC2634(T). Are these the same? Which equivalent can I use?

This is P 507 connector. Green wire is out, i suppose that next would be a blue wire, I found a cutted one under the capstan. I have a few pictures and I can see the blue wire, but I don't know if I need another wire in last position and where it goes. Maybe somebody help me with good pictures and explanations

On J503 i found a black wire cutted. I don't know where it goes.

ChrisMarantz · May 4, 2012

Little Diode has 2SC2634 in stock. 1.86 euro and they are close to you.

paul_ral · May 4, 2012

I'll search for these transistors in my country. According http://www.datasheetcatalog.org/datasheet/panasonic/SJC00119BED.pdf
the difference between 2SC2634(S) and 2SC2634(T) is rank classification, 260 to 520 for S version and 360 to 700 for T one. Can I use a single version?

BOUXY · May 4, 2012

Seeing this I'm so happy I stuck with my Simple SD-3000 2 Speed as it is fancy enough and looks,works,sounds fantastic

P/S Paul Demara is a friend of mine quite a big Marantz Fan and lot's of info

paul_ral · May 6, 2012

Today I removed the old belts. Thi is a picture of old belts

New belts from Germany. I ordered them for my SD 420 to my friend, but he send my these. I'm a lucky guy.

New belts on the deck. These are thinner than OEM ones and the left looks to be wide

Somebody tried to remove the optocuplors

I removed the loading pannel, and have to solder LED diodes because somebody damaged the board before me.

I fixed this push button

The blue wire was cut

Studying the schematic i found that P 507 and P 508 connectors are reversed. The blue wire goes to P 508 connector. It has only 9 pins, right?

paul_ral · May 12, 2012

Working on power supply and BIAS osc board (P400). Transistor Q432 2SD131 was replaced with 2SB1357. I have to put the OEM transistor back.

paul_ral · May 19, 2012

Today I ordered all missing parts from Germany. I bought another power supply and main boards, all parts cost me 72euro including shipping.

ChrisMarantz · May 19, 2012

Nice to see that things are coming along :thmbsp:

paul_ral · May 24, 2012

Today I received the parcel from aboard. Very fast shipping, 3 days from Germany to me. I enjoyed as a child. I have a half of 8020 in my bed as you seen in the pictures. He sent me 3 cassettes, one tape head and the front panel as a gift. Unfortunately, he forgot to drop in the programming switches, it will be done in next parcel. I'll take the capstan and the second motor and programming board, too.

Marantz SD 8020 - mission impossible?

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