Hagstrom 26 Help

SaMpLeGoD · Aug 30, 2014

Hello all! I got a Hagstrom 26 to repair... it's a nice swedish early 60's amp with tremolo

Searched all the net about info but got nothing that helps...
I did a quick reverse engeneering, cause I found no schematic available...
There's no sound comming out of the amp, sometimes sound can be heard but it's distorted, well... checked all the voltages and all seem to be ok... just 3 tubes (EZ80 - rectifier, EL84 - power and 12AX7 - preamp).

I'm wondering one thing... theres a small square with 5 lugs from Nichicon labeled 5M-001, you can see it n yhe last photo in this post... I really don't have a clue what is that... anyone?
I'll attach the photos!
Cheers

PRR · Aug 30, 2014

The ceramic blob has many of the resistors and capacitors needed to couple out of one plate into the next grid.

The one in the photo looks like a lead has been broken and "repaired". That is a dubuous thing.

Do you have one 5M-001, or two 5M-001?

The schematic is obviously missing a connection from first preamp to power amp. I bet pin 1 of the left 5M-001 goes to Grid 1 of the EL84. 1Meg is the right size of resistor, and assuming the 5M-001 has a capacitor inside to block preamp plate voltage, that makes the most sense.

> amp don't pass sound, well... sometime pass but distorted...

It isn't going to be a High Gain amplifier, because it only has one stage of 12AX7 before the power tube. Input sensitivity for full output is about 100mV, compared with 20mV for classic Fenders. You will want a booster in front of it to make it break-up.

It isn't as loud (maxed-out) as a Champ because of the very low B+ voltage on the power stage. Looks like 3 Watts.

The voltages do not look right. You have 284 Volts AC going into the rectifier? With perfect rectification this would give 400V DC. With Vacuum rectifier and this sort of load I would expect 320V (and a good 5+ Watts output).

The "sometimes" is a sure sign of a Bad Connection. The bodged blob is one likely trouble spot. Dirty sockets and tube pins always happen. Solder joints can be bad. Jacks, pots... all must be perfect connections to have a good reliable amplifier.

Sure is pretty inside.

That black 32+32 filter cap looks like a recent (last decade) replacement.

Repair? Could be a LOT of work for a small cute but no-value amplifier. Is the client prepared to pay for a lot of time? Is the client interested in "exact restoration" or a good working amplifier for home use?

Personally I'd think about trashing the 5M-001 blobs, wiring a plain Champ. Two stage preamp (ample sensitivity). No tremolo (there's pedals for that now, and they are better). The trem pot can be a tone control, trem switch a normal/more bass switch.

BTW: "Hagstrom", not "Hangstrom". They are a long-time accordian and guitar company 1930s-1980s (the name is still in use).
http://www.hagstromguitars.eu/index.php?option=com_zoo&view=item&Itemid=2
http://en.wikipedia.org/wiki/Hagstr%C3%B6m

SaMpLeGoD · Aug 31, 2014

Hello! thanks for the fast reply!
Yeah, it's a kind of a sentimental issue between the client and this amp, so he only wants the amp running...
The amp was serviced before, for sure! all the caps are brand new (the 32uF+32uF/500V is a JJ cap) there's one new F+T... just the resistors and the brown "5 leg blobs" as well as the trafos are stock.

The EL84 and the EZ80 looks like old stuff... the EL84 is marked: Philips EL 84 "KM2 B704"... I investigated and it was made in England early 60's (61 to 65). I replaced with a new one and nothing happened...

About the EZ80, I need to check out if it's working propertly, I do think too that the DC voltage produced isn't right for a 284VAC at the Input... so I'm getting the tube's plates very cold... I'll try to replace with another... Here in Portugal there are a few very old shops that have unbeliavable NOS stuf...

PRR said:
Do you have one 5M-001, or two 5M-001?

I have two 5M-001... as you can see in this photo below

PRR said:
The schematic is obviously missing a connection from first preamp to power amp. I bet pin 1 of the left 5M-001 goes to Grid 1 of the EL84. 1Meg is the right size of resistor, and assuming the 5M-001 has a capacitor inside to block preamp plate voltage, that makes the most sense.

You are right about that... but as you can see in the photo bellow, 5M-001 pin 1 goes to PIN 1 of the EL84 that according with the tube's datasheet pin1 is disconnected... and the 1M resistor goes from the same EL84's pin 1 to ground... so I assumed that it functions like a bridge to get the things connected... as you can see, pin2 (grid 1) of the EL84 has no solder...it was never soldered! perhaps the guy who serviced the amp changed the socket and made a mistake, I dont know... humm... ok, but the socket seems to be old, so it's probably the original one.
Check it out...

Is there any "discrete" circuit to substitute that ugly blob? can you help me on that?

At last... you're right Hagstrom not Hangstrom... I corrected in the subject post!
Thanks

PRR · Aug 31, 2014

> see, pin2 (grid 1) of the EL84 has no solder...it was never soldered!

Last time I saw something like that, the amplifiers had burned-up. With flames. Inside a film transfer studio.

Better fix that before doing ANYthing else.

panman · Sep 1, 2014

SaMpLeGoD said:
Is there any "discrete" circuit to substitute that ugly blob? can you help me on that?

I would second, what PRR suggested, exept I don`t have experience of the tremolo-pedals: "Personally I'd think about trashing the 5M-001 blobs, wiring a plain Champ. Two stage preamp (ample sensitivity). No tremolo (there's pedals for that now, and they are better). The trem pot can be a tone control, trem switch a normal/more bass switch."

SaMpLeGoD said:
At last... you're right Hagstrom not Hangstrom... I corrected in the subject post!
Thanks

Hope you don`t mind, but it`s not yet correct. It should be Hagström. The logo has the t-line extending longer depicting the two dots over the letter "o".

SaMpLeGoD · Sep 1, 2014

panman said:
Hope you don`t mind, but it`s not yet correct. It schould be Hagström. The logo has the t-line extending longer depicting the two dots over the letter "o".

I know that... but was lazy to search for the ascii code for that "o" :
rock on