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Author Topic: Solec 1980's SS guitar amp first chip amp? schematic  (Read 3647 times)

galaxiex

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Solec 1980's SS guitar amp first chip amp? schematic
« on: November 30, 2016, 09:13:18 PM »
Once again....  :o

I have discovered an eBay gem???? Ha Ha!  :lmao:

When I got this I thought it would be a candidate for a "real" chipamp like a LM3886.
But after playing with it and changing some component values I think I'll keep it with the original chip amp.
It's a TA7202P and I can't find a data sheet for it, but lots of NOS on eBay if I need to replace it.
The eBay sellers say it's a 6.5W chipamp.

Is this one of the "first" chipamps?

Plenty loud thru the original 2X12 cabinet.

Looks like the original TA7202P was already replaced as the copper tracks are mangled, but whoever replaced it, they managed to get it working.

2 schematics here, the first with the "original" parts values as it came to me.
It all "looked" original except for the TA7202P.

The second schem is after I played around with it some.
Parts changes are... R3, R4, R5, R10, R17, R23, R20, R21, R25, C12, C14, C15, C16, C17,

One BIG improvement was to change R3 to 1M.
The amp got really LOUD when I did this, but the trem stopped working.

Fiddling around with the trem circuit, I got it working again.
Parts values as shown in the schematic and layout.

If you look at the thread with the National GA-920-P amp, you will see some similarities to this one,
re; the input stage and the trem circuit.

Since the National already sounds good I "copied" some of the parts values.

This thing actually sounds quite decent for an 80's SS "cheap and cheesy" amp.  :o

Note; I did replace ALL electro caps and this made a huge improvement, including the chip amp has a turn-on delay that was very loooong with the original caps.
Now the turn-on delay is very short. Maybe 1-2 seconds. Before it was about 6-7 seconds.

Fun amp.  :)

Oh, the 2X12 cab has some no-name drivers, 8 ohm each, wired in parallel for a 4 ohm cab.
Lotsa bass!

Oh ya, the original transformer was replaced at some time, the mounting holes are different.
No matter it seems to work ok.
« Last Edit: November 30, 2016, 09:31:58 PM by galaxiex »
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DrGonz78

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #1 on: November 30, 2016, 11:47:53 PM »
That's a nice looking cabinet with that amp! No-name speakers back in the day are probably better than many brand named types of today. Great post keep it up!!
“A person who never made a mistake never tried anything new.” -Albert Einstein

galaxiex

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #2 on: December 01, 2016, 01:49:30 PM »
Thanks DrGonz!  :)

The cabinet would be nicer if it wasn't made from that horrid particle board.
I'm actually surprised it has lasted this long.  :o

One good accidental drop or hit and it would likely disintegrate!
Not to mention, don't get it wet! It'll just melt!

It's also quite heavy....

Oh well... it is what it is.

On keeping going...  ;) I have yet another 60's 70's amp head that needs ALOT of work.

I also need help identifying it.

I'll start a new thread....
Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering.

galaxiex

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #3 on: December 03, 2016, 03:56:42 PM »
Here's the guts of the Solec speaker cab.

It's all that cheesy particle board except for the thin back panel.  ::)
Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering.

DrGonz78

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #4 on: December 04, 2016, 06:32:28 AM »
Here is a link lightly talking about something that might relate to those speakers.
http://forums.vintageamps.com/viewtopic.php?p=417370

From what I could gather is they are possibly made by RSC, Radio Speakers of Canada. Who knows?? Do you see an RSC stamp anywhere on them?

Also one mention of a Solec amp on DIY site.
http://www.diyaudio.com/forums/solid-state/171776-solec-ic-46-japan.html

« Last Edit: December 04, 2016, 06:36:19 AM by DrGonz78 »
“A person who never made a mistake never tried anything new.” -Albert Einstein

galaxiex

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #5 on: December 04, 2016, 11:46:34 AM »
Thanks for those links.  :)

I will pull the back panel and a driver and see if I can find a RSC stamp on them.

The Vintage amps forum link is interesting.
I have a Traynor Guitar Mate III that has the original RSC/Marsland driver in it. (so I was told)
I will have to open that one up and check the codes on the speaker.

Interesting that the diy thread never got a reply and the poster says he bought it in Canada.

I beginning to suspect that these Solec amps were "made" in Canada.
Certainly the amp chassis and circuit was made in Japan,
but all the rest...

The seller I bought this amp from is in Quebec.

With the exception of the screws on the actual amp chassis,
ALL the screws on the speaker cab and head are those funky Robertson screws.

Far as I know, the Japanese have never used Robertson screws.
They seem to prefer Phillips..... and the Robertson type are a Canadian invention.

Pure speculation,
but I think maybe these Solec amps were a house brand for a (now defunct) Canadian department store.
Woodwards and Woolco, are 2 I can think of off the top of my head.

Judging by the lack of info out there, these amps seem to be quite obscure/rare.
I know rarity does not equal value. No matter.
If it's a Canadian only sold product, that makes it interesting to me.  :)

Cheers!
Dale

Edit; Hmmm further investigation seems to indicate that Solec amps were sold world-wide under various brand names.
« Last Edit: December 04, 2016, 12:05:56 PM by galaxiex »
Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering.

J M Fahey

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #6 on: December 04, 2016, 05:37:35 PM »
Probably Canadian cabinets and speakers (large/heavy, cheaper to source locally avoiding Customs and Freight) and Japanese Electronics bought by the truckload, where smaller size/weight and higher cost justifies importing.

Today freight is SO cheap and Tariff SO low that China/Korea/Vietnam are "next door".

galaxiex

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Re: Solec 1980's SS guitar amp first chip amp? schematic
« Reply #7 on: December 04, 2016, 07:31:07 PM »
Probably Canadian cabinets and speakers (large/heavy, cheaper to source locally avoiding Customs and Freight) and Japanese Electronics bought by the truckload, where smaller size/weight and higher cost justifies importing.

...

Yes, this makes sense.
Thanks!
Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering.

 

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