freestompboxes.org

hi everybody,

trying to touch up my vintage pearl f-605 analog delay. ordered the original japanese 2sa495 that is in the power section...
does anybody have one, or pics of the component side ? a schem would help even more, but i know this one´s really rare.
the reason i want pics of the component side is that one of the previous owners had already messed around with it and i´m not sure if some of the things i see are supposed to be that way...

cheers,
lohstah

If you can wait.... I have one.... somewhere I even have the schematic tracing too. A nice delay with a special feedback feature, but sadly without a compander.

Dirk Hendrik may also have one ?

analogguru

He may....
Had one over fror repair with just that failure 3 weeks ago. Reversed polarity on the power supply causes this problem. The transistor is part of a "voltage regulator" with a zener. It's abolutely non-critical in the type of transistor used as long as it is PnP. Datasheet can be found on datasheetarchive.com.

In the meantime:

2SA 495: Si-PNP 30V/100mA/200mW ß: 40-240/10mA fg: >100MHz

analogguru

thanks guru and dirk,

i already have the 2sa495 at home (wasn´t clear about that in my first post i guess ), so the power section is not my main concern right now, but in the upper right hand corner of the pcb there is a black wire next to the mn3005 that just has been cut. so i wonder where that one would go to normally .
that´s why pics or a pair of eyes would be helpful.
thanks for the help and interest so far,

lohstah

The fact that you're working on a Pearl Unit of the F60x series suggests you're in Europe. Where? (or, photo's + phonecall might work faster)

dirk, you got mail (your website info@.... adress).

cheers,
lohstah

Got it. Lemme find a free moment now (with daylight) to shoot some photo's.

i'd love to see a schematic too!!

i've been trying to snatch one up on marktplaats (dutch ebay type of site) but i'm always too late.

EDIT(gotta start reading better DOH) %since i've got an alecto bbd echo with a mn3005 i'm wondering if the pearl is based on that chip too. Since the alecto is totally unusable without my boss line selector (can you spell tonedrain!) %





@ dirk hendrik leuk om je hier ook te zien Nice Forum hier! Ik kom de laatste tijd nogal vaak op het newtone forum.

Hobie wrote: @ dirk hendrik leuk om je hier ook te zien Nice Forum hier! Ik kom de laatste tijd nogal vaak op het newtone forum.

Hoi,
Het genoegen is geheel wederzijds,

Lohstah,
I did think about you..... And shall try to do some more.

The thing is based on a 3005 indeed. It is however a very crowded pcb and not very DIY friendly for the low to medium advanced DIY-er.

Lohstah,
I did think about you..... And shall try to do some more.

cool ! i was already wondering...

i´m all ears and eyes...

cheers,
lohstah

...the original japanese 2sa495 that is in the power section...

I had a look and my unit (from 1978) contains only:
1 x 2N 5462 FET
8 x 2SA 564A-R 45V/100mA/250mW ß:180-360/2mA fg>80 MHz
1 x 2SA 777-R 80V/1A/750mW ß 130-220/150mA fg>120MHz

The last is (together with a 1k and a 15V zener) responsible for the -15V PS-stabilization.

Maybe you can have a look at the MC1458 what is written in the second row (date code) ?

analogguru

hi guru,
thanks for chiming in again.
there is no 1458 on my board, it contains 4xC4558 (NEC), one D4013C (NEC), and one MN3005.

one of the potis (delay time) has written "M1M(ohm)B" on it and the second line says "731J". maybe a code for the production date of the pot ?

transistors in my unit are: 8x 2SA564A (second row "R .7N"), one 2N5462, and the one in the powersection (mine had a retrofitted MPSA92 with legs bent to match the pinout).

i´ll try to take pics and post them.

chers,
lohstah

ok, two pics:




cheers,
lohstah

Your unit seems to be identical to mine, except that yours seem to be younger..... yes and I have one transistor in the 3 holes at the lower left corner.....

Maybe somebody took it out ?

analogguru

oh, on the lower left corner is one of the 2sa465, i have it (my dad took it out to take some measurements i guess).
the one i want to replace is on the right upper-hand corner, where the socket is (i put it there to be able to try out different transistors).

to clear some things up, the unit was always working with batteries, but not with the dc plug, and i felt it was noisy, so i wanted to check if something could be done...different replacement transistors for the one in the power section yielded different results noise-wise, so i thought that getting the right one would give me the best results (without having to re-bias the whole thing, which is also a bit of a pain in the ass without a schematic).

so what would help me:
if dirk would confirm that his unit has a 2sa495 in there ?!?
guru, do you see those two short black wires, one between the 4013 and the 3005 on the lower left (near pin 14), and the other one next to the trim pot on the upper right corner of the mn3005 (near pin 7) ? are they connected on your unit ?
and, since my dad worked on the unit first (one year ago) and did not take sufficient notes, what is the orientation of the zener and the pnp in the power section ?

cheers,
lohstah

Here we go:

transistor
z-diode

analogguru

hey analogguru,

thanks for your help so far !
are the two black wires near the mn3005 connetcted somewhere on your unit ?
finally, if it´s not too much to ask, a pic of the whole pcb (component side) and the wiring would be great !
just came home from work today and have to go to a rehearsal, tomorrow i´m gonna solder the stuff back in again and see what happens !

cheers,
lohstah

UPDATE:
put it together again today, using the 2sa495 i had, and everything working perfectly. more headroom with the two batteries (15V as opposed to the 12V from the plug). i wonder if i can just use 15V on the dc in for the same headroom ?

even unsoldered the "battery check" led to test if it´s ok, and it is. it seems the circuit is configured in a way that the battery led starts glowing when the voltage starts to get lower ?

so, thanks for all the help i got !

just out of curiosity, i wonder if guru´s f-605 has the same two black wires near the mn3005 that go nowhere...maybe they´re test points to connect the oszi when setting the trimpots ?

cheers,
lohstah

Hey, now I have one too

Friend of mine bought it a long time ago; didn't work so he thought he throwed it away. Turned out to be somewhere in a box. PSU is wrong so I'll check the PSU section

So, anyone has a schematic of this baby?