Metropoulos Forum

Hi there and greetings from Finland.

I just managed to finish my first PTP Marshall, and actually my first amplifier ever. All my previous soldering work so far had been just fixing guitar or mic cables, but as I aqcuired a Marshall 1987S (a somewhat rare '88 reissue of the 1987 50W Lead) which was already "hot wired" by Björn Juhl, I decided I would try to build a new PTP board for it. So I ordered a Metroamp 50W Lead kit and a couple of days later I had a working 50W Lead Marshall. Wow! What was even more rewarding for a total newbie like me was the fact that the amp worked right away and all I had to do was to bias it.

Then some suggestions and ideas most of you probably have already come across:
According to the instructions there should be a "white bias wire from transformer" and I couldn't find it at first. Then I checked out the pictures I luckily had taken before disassembling the previous PCB and noticed that the white wire is actually coming from the standby switch to the 220k bias resistor and that seems to be the case in all 50W models. In case it hasn't yet been corrected to your instructions I think it's a thing worth mentioning: it really puzzled me since I haven't built a single amp before - I actually noticed some other people talking about the same thing on the Metroamp forum. Also, the wiring instruction image for the input jacks lacked the ground wire. Of course it's obvious that a ground connection is needed in the jacks, but newbies like me might get a bit confused at first. One more thing worth mentioning is that only carbon film resistors should be used in the signal path - they are better tone-wise, if I understood correctly. I myself installed a couple of metal oxide resitors in the "wrong place" at first, but changed them to carbon film ones as my knowledge increased. This has actually been a really nice learning process "with a little help from my friends".

I recorded some sound clips with my friend Sam Vilo. If you wanna check them out, feel free to try this address:
http://mp3.jucciz.com/marsu/

There's also a collection of "timeline pictures" from the parts' arrival day to the final working and tested amp in case you're interested. These are sorted chronologically from oldes to newest:
http://jucciz.com/kuvia/kitarat/marshal ... t/?C=M;O=A

Here's the "specs sheet" for the amp:
http://jucciz.com/?section=amps&page=lead50w
There's also some info about my other amps there. Feel free to look around.

Many thanks to George for fantastic customer support and top quality parts! Great guy, great attitude and most of all: great tone!

Cheers,

Jukka-Pekka "Jucciz" Berg
Finland

BTW: If anyone has a spare bulb of a proper size: please drop me a letter ... not that the current one wouldn't work but ...

Nice Presentation My Good Man... Pic's & sound files are Great.
Now go to the refrigerator and grab yourself a beer !

JimiJames wrote:Nice Presentation My Good Man... Pic's & sound files are Great.
Now go to the refrigerator and grab yourself a beer !

Thanks for your feedback. Actually I had a few of bottles there, so I did what I was told to do. Thanks for the hint!

By the way, looking at "old" Marshall heads and the X series reissue models, I noticed that this 1987S model looks slightly different: the horizontal "golden line" divides the front side of the amp approximately in half, so the white Marshall logo isn't as close to the upper edge as in all the other models I've seen. Also, this one has a polarity switch instead of a "JMP" or "MK II" text. The switch itself is a dpdt which isn't connected at all. Any idea if these are visual details only found in year 1988 re-issues.. or is there an "ancient" Marshall model that looked like these? Especially the horizontal line puzzles me, I do know that in the old days the polarity switch existed for a reason. I personally think that it looks kinda cool and more "balanced" this way, so I'm happy to have it this way. But please tell me everything you know about this matter, I would be glad to hear about it.

See the picture: http://jucciz.com/kuvia/kitarat/marshal ... G_8777.JPG

Now we'll see if we really have Marshall experts here.

Well, my scandiavian friend (I

That series of reissues were the only Marshalls with the head cases done that way, makes them very easy to spot!!

Thanks for all the info so far.

I'd hate to say the piping is "too low", because I really like the way it is. Now that I've grown used to it I actually think that all the remaining 99,98% Marshalls look a bit weird: the logo, as well as the piping, is positioned a bit too high. ;)

The "polarity" switch in the front panel is just a dummy switch that isn't wired at all, but of course it could be used for switching for example a capacitor on/off the circuit (V2a bypass cap etc.) We'll see...

The head case IS a Marshall 1987S, which is a model 1987 reissue from year 1988, the only year those were made. I actually bought it from Sweden (I guess we're even now) where the amp-guru Bj

Awsome pics. Gives me confidence that I might be able to do that myself. Looks much less daunting in stages like that.

I just wanted to say that I've only just got round to listening to clips on this one! I couldn't play them at work when I first read this thread.

STONKING sounds! LOVE it. Now that's TONE.

You can do anything with that sound. Except maybe Metal. And who want's to do that?

It looks and sounds great!!!!

I realize this is a late post.But I have had the 1959 super lead 100w head for 29 years and it also has the polarity switch.This switch was added because it was designed with a 2 prong AC cord.Instead of flipping the plug to change the flow of current you would use the polarity switch.I know this as I have received many shocks when using the amp on concrete floors )

That's as maybe, but on the 1987S it is purely cosmetic. Not even wired.

This link is helpful to some.You probably already been there.
http://www.blamepro.com/mar/date1.asp" onclick="window.open(this.href);return false;
Check out this amp I found tossed away on a curb.A SOVTEK MIG100.

Jucciz wrote:.

Then some suggestions and ideas most of you probably have already come across:
According to the instructions there should be a "white bias wire from transformer" and I couldn't find it at first. Then I checked out the pictures I luckily had taken before disassembling the previous PCB and noticed that the white wire is actually coming from the standby switch to the 220k bias resistor and that seems to be the case in all 50W models. In case it hasn't yet been corrected to your instructions I think it's a thing worth mentioning: it really puzzled me since I haven't built a single amp before - I actually noticed some other people talking about the same thing on the Metroamp forum. Also, the wiring instruction image for the input jacks lacked the ground wire. Of course it's obvious that a ground connection is needed in the jacks, but newbies like me might get a bit confused at first.

Actually, the chassis layouts I have of the 2204 and 1987 amps show the white wire to the board and also shows the shield from the input cable going to the ground buss.
Not sure what layout you used.
Sometimes on the layouts it's hard to see the shielded ground part because it is drawn very faintly with a grey color.

Nice looking conversion you have there and it sounds great.

Some good enginuity on the pilot light also.

Jucciz wrote:Thanks for all the info so far.

I'd hate to say the piping is "too low", because I really like the way it is. Now that I've grown used to it I actually think that all the remaining 99,98% Marshalls look a bit weird: the logo, as well as the piping, is positioned a bit too high.

The "polarity" switch in the front panel is just a dummy switch that isn't wired at all, but of course it could be used for switching for example a capacitor on/off the circuit (V2a bypass cap etc.) We'll see...

The head case IS a Marshall 1987S, which is a model 1987 reissue from year 1988, the only year those were made. I actually bought it from Sweden (I guess we're even now) where the amp-guru Bj

I know this is an ancient thread - but for archiving purposes, I want to state that my stock 1988 Marshall 1987S head has a fully-functional polarity switch. It is not a "dummy" switch.

Jucciz wrote:"...I recorded some sound clips with my friend Sam Vilo. If you wanna check them out, feel free to try this address:
http://mp3.jucciz.com/marsu/

Has this been posted here on Metroamp, or just on Plexi Replicas facebook page?