45rpm Running in problem

[Blockbusters]

Does anyone have an idea where to look for the following problem?
A friend of mine allso owns like me a B291 turntable.
His turntable play's exelent. The only problem is that when he want's to play a single
the arm doesn't go to the start position.
So I started with replacing all caps and washed the print with special electronical soap.
Fitted everything together and he runs in 1 time.
Then I swapped the microchip 1.179.353.21 same result. So it's not in there.
In the service manual I can't find anything about which part or ic is responcible for running in to the startposition.

Does anyone of you know where to search?

Meine Revox Geräte:
B790, B215 mk2, B285, B225, B205
B291, B215 mk1, B250, A725, A727, A721. B208
Equipment is upgraded with Jensen, Duelund , Mundorf and Panasonic FC/FR capacitors and Burr Brown opamps.
Revox is poisonous. Once you listen to it, Everything else become abnormal sounding.

[borchee]

Hi Rob,

sadly, I'm guided only by intuition...so, here go my two cents.

Read the tonearm control section 4.4 again - especially 4.4.4 Automatic positioning.

As the function basicaly works, altough did just once, you might check the contacts (connector tonearm to electronics PCB - pins from the photo diode DP3...cleaning it, with the other two and the LED also, can't hurt), for broken traces and cold solder joints. Do the same for IC17, the microprocessor ( bad contact in socket is likely) and R154 (if it's an open type, It might be faulty).

Roughly speaking, check the path, and everything on it, from photo diode DP3 to microprocessor IC6.

Good luck.
Borut

[Blockbusters]

Hi Borut,

Thanks for this information.

I found the tonearm control section 4.4.4.
As you would understand I allready checked connectors and cold solder points.
And after checking and double check I thought let's ask it on the forum.
Gues what, You were right, the probllem was in R154. it stood a bit open, so no contact.
Replace this one and now the player does what he has to do.
So again thanks for the tip.

Kind regards
Rob

Meine Revox Geräte:
B790, B215 mk2, B285, B225, B205
B291, B215 mk1, B250, A725, A727, A721. B208
Equipment is upgraded with Jensen, Duelund , Mundorf and Panasonic FC/FR capacitors and Burr Brown opamps.
Revox is poisonous. Once you listen to it, Everything else become abnormal sounding.

[borchee]

Hi Rob,

Gues what, You were right...

I grew an inch...or two.

Glad to hear, I was of some help.

Groetjes
Borut

[Blockbusters]

Well Borut,

I would grew allso a few inches
Anyway my friend is happy the turntable goes automatic to the single position again.
Pitty you live that far away, otherwise he would offer you a beer

Kind regards
Rob

Meine Revox Geräte:
B790, B215 mk2, B285, B225, B205
B291, B215 mk1, B250, A725, A727, A721. B208
Equipment is upgraded with Jensen, Duelund , Mundorf and Panasonic FC/FR capacitors and Burr Brown opamps.
Revox is poisonous. Once you listen to it, Everything else become abnormal sounding.